Hans-Balder Havenith
email: hb.havenith@ulg.ac.be

Céline Bourdeau

AN INAUGURAL LECTURE TO THE SOCIETY EARTHQUAKE-INDUCED LANDSLIDE HAZARDS IN MOUNTAIN REGIONS: A REVIEW OF CASE HISTORIES FROM CENTRAL ASIA

Keywords: Mass movements, seismo-tectonic and geological factors, site effects, liquefaction, long-term effects, Tien Shan and Pamir Mountains Mouvements de masse, facteurs sismo-tectoniques et géologiques, effets de site, liquéfaction, effets à long-terme, montagnes du Tien Shan

This paper presents a summary of the main trigger factors of earthquake-induced landslides as well as a review of case histories of major landslide-triggering earthquake events in Central Asia. The Kainama earth-flow case history of 2005 is added to document possible mid-term effects of smaller earthquakes. These events show that in the Central Asian Mountains, two types of seismically triggered mass movements may have particularly disastrous effects: massive long runout rockslides and medium-sized earth flows made of loess -or a mixture of both. These types of mass movements also significantly contributed to the largest natural catastrophe of the last century in Central Asian mountain regions: the 1949 Khait earthquake. The high impact potential of these types of mass movements is further pointed out through comparison with two worldwide known events, the 1920 Haiyuan (China) and the 1976 Peru earthquake. Case studies had been carried out on rockslides, debris slumps and earth flows triggered by the above-mentioned Kemin and Suusamyr earthquakes as well as other smaller seismic shocks in the Kyrgyz Tien Shan. Many of the investigated landslides had known a complex failure history before final collapse. To better assess the short-to long-term effects of earthquakes on slopes, landslides need to be surveyed more intensively, over mid-and long-terms.

Introduction

During the last ten years, after a series of disastrous earthquake events in mountain regions in Taiwan (1999), El Salvador (2001), Pakistan (2005) and China (2008), increasing attention has been addressed to landslides triggered by earthquakes.

Previously, landslides have been considered as minor effects of earthquakes compared to the impact of the ground shaking itself. Schuster & Lynn (2001) partly attributed the perception of the relatively small impact of earthquake-triggered mass movements to the fact that many related losses are often referred to as direct consequences of the earthquake. The assumption of the global 'secondary' importance of earthquake-induced landslides and other ground failures was confirmed by a study undertaken by Bird&Bommer (2004) -even though they also admit that, for some earthquake risk scenarios, seismic ground failures need to be taken into consideration to correctly estimate total losses. Explicitly, it was only noticed for the two El Salvador earthquakes in 2001 that 'the most devastating impact … has been the triggering of hundreds of landslides in volcanic soils, …' [START_REF] Bommer | The El Salvador earthquakes of January and February 2001: context, characteristics and implications for seismic risk[END_REF].

This study of [START_REF] Bird | Earthquake losses due to ground failure[END_REF] had been completed well before the M=7.6 earthquake hit the Kashmir mountains on October 8, 2005. For this event, [START_REF] Petley | Incipient Landslides in the Jhelum Valley, Pakistan Following the 8th October 2005 Earthquake[END_REF] estimated that about 30% of the total number of killed people (officially 87350), i.e. 26500, had been victims of co-seismic landslides. Less than three years later, on May 12, 2008, the Wenchuan earthquake hit the Sichuan and neighbouring provinces of China and caused 'more than 15000 geohazards in the form of landslides, rockfalls, and debris flows, which resulted in about 20000 deaths' [START_REF] Yin | Landslide hazards triggered by the 2008 Wenchuan earthquake[END_REF]). These deaths represent again almost 30 % of the official total number of fatalities of 69197 of this event.

In this paper, we will evaluate the potential impact of landside hazards induced by earthquakes on the basis of a review of related geological observations. However, we do not aim at statistically reviewing earthquake-induced landslides events, related trigger mechanisms and impacts. For this, we refer to the works done by [START_REF] Keefer | Landslides Caused by Earthquakes[END_REF]Keefer ( ad 1999) ) and Rodriguez et al. (1999).

Here, focus will be on the relatively poorly known Central Asian mountain regions, the Tien Shan and Pamir, on the basis of landslide case histories related to the following earthquakes (see location in Fig. 1 and a summary in Table 1): M=8.2 Kemin, 1911, M=7.6 Sarez, 1911, M=7.4 Khait, 1949, M=5.5 Gissar, 1989and M=7.3 Suusamyr, 1992. One landslide case history is added to document the mid-term effect of small and medium-sized earthquakes on slope stability and related hazards in the Tien Shan Mountains.

Two other M>7 earthquakes of the last century in the Tien Shan Mountains will not be further documented here since we know only little: the M=7-7.4 Chatkal earthquake in Western Tien Shan, for which some data about triggered mass movements and landslide dams are provided by [START_REF] Leonov | Role of geological structure in the formation of residual deformations of soils during earthquakes[END_REF], and the M=7.3 Markansu earthquake affecting remote areas of the Southern Tien Shan, for which [START_REF] Nikonov | Seismotectonics and Earthquakes in the Pamir -Tien Shan Convergence Zone[END_REF] indicated very few data about induced ground failures.

The documented earthquake case histories of Central Asia will be compared with some of the worldwide most disastrous events, and particularly with the M=8.5 Haiyuan (or Gansu, 1920) and the M=7.8 Peru (1970) earthquakes. These two events caused the greatest number of deaths in history through multiple triggered landslides and a single mass movement, respectively [START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF]. Further, our analysis will focus on those types of mass movements, which caused these disasters: rapid flows (mainly) in loess deposits and massive rock avalanches. Actually, those types also induce the highest geological risk in Central Asian regions, such as shown in the following. For a complete review of landslide types triggered by earthquakes -including submarine landslides -, the reader is referred to [START_REF] Keefer | Landslides Caused by Earthquakes[END_REF][START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF] and Rodriguez et al. (1999). Special attention will be paid to long-term effects of earthquakes in mountain regions. Examples will be shown for clearly delayed triggering of slope failures after earthquakes and post-seismic increase of landslide activity, such as observed after the Chi-Chi earthquake of 1999 in Taiwan [START_REF] Dadson | Earthquaketriggered increase in sediment delivery from an active mountain belt[END_REF]. In this regard, we will also analyse previously called 'secondary or tertiary effects' of earthquakes, such as natural dams and related flooding impacts. In the Tien Shan, the most recent massive natural dam was formed after the Suusamyr earthquake in 1992 -it partly failed in 1993, thus causing a long-runout debris flow and widespread flooding downstream. The 2008 Wenchuan earthquake clearly marked the importance of such effects -which could have killed another few thousands of people if efficient mitigation measures had not been taken by Chinese authorities. For these cases, it will be shown that the term 'consequential hazard' proposed by [START_REF] Korup | Geomorphic hazard assessment of landslide dams in South Westland, New Zealand: Fundamental problems and approaches[END_REF] should be preferred over 'secondary of tertiary effects' implying a lesser degree of importance.

Geological and morphological setting and earthquake-induced landslide types

This section analyses where landslides are preferentially triggered by earthquakes within seismically active mountain belts with respect to seismo-tectonic, geologicalstructural and morphological factors.

For a classification of seismically triggered landslide types we refer to the extensive work of [START_REF] Keefer | Landslides Caused by Earthquakes[END_REF][START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF]. Here, we will just introduce the general categories of earthquake-triggered landslides defined by [START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF]. These include 1) 'Disrupted Slides and Falls', 2) 'Coherent Slides and Landslides', 3) 'Lateral Spreads and Flows'. As mentioned above, for Central Asian mountain regions, massive rockslides and rock avalanches as well as loess earth-flows are the most hazardous types of mass movements. These belong, respectively, to the first and third category of rapid mass movements.

Seismo-Tectonic factors

According to [START_REF] Keefer | Landslides Caused by Earthquakes[END_REF] and [START_REF] Rodríguez | Earthquake-induced landslides: 1980-1997[END_REF], landslides may be triggered by earthquakes with a magnitude equal or larger than 4. [START_REF] Sassa | Prediction of earthquake induced landslides[END_REF] further observed that seismic landslide occurrence is strongly dependent on the proximity of the fault rupture. More recently, [START_REF] Yin | Landslide hazards triggered by the 2008 Wenchuan earthquake[END_REF] highlighted that 'the distribution of landslide-dammed lakes is closely related to proximity to the earthquake fault in the Longmenshan Mountain system. There were 22 landslidedammed lakes distributed within the earthquake fault belt, which is 1/3 of the total number of landslide-dammed lakes'. All over China, [START_REF] Wen | Characteristics of rapid giant landslides in China[END_REF] observed that 'the locations of most of the giant landslides are very close to the major fault zones… particularly the active earthquake zones'. After the Chi-Chi earthquake (1999) in Taiwan, [START_REF] Khazai | Evaluation of factors controlling earthquake-induced landslides caused by Chi-Chi earthquake and comparison with the Northridge and Loma Prieta events[END_REF] outlined that 'the majority of the landslides occurred within a distance of 20 km from the fault rupture plane on the hanging wall on south and southeast facing slopes. Less than 10% of the landslides occurred on the footwall.' Similarly, for the Kashmir earthquake in 2005, [START_REF] Petley | Incipient Landslides in the Jhelum Valley, Pakistan Following the 8th October 2005 Earthquake[END_REF] noted that 'close to the fault rupture there was a high incidence of landslides triggered by the Kashmir earthquake... The distribution of landslides appears to be very asymmetric, with most of the landslides being located on the hanging wall (north-eastern) side of the fault'. For the same event, [START_REF] Sato | Interpretation of landslide distribution triggered by the 2005 Northern Pakistan earthquake using SPOT5 imagery[END_REF] further noticed that more than one third of the landslides occurred within 1 km from the active fault. [START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF] studying ground failures in the Suusamyr region, Northern Tien Shan, observed that 'seismic deformations are concentrated to active Neotectonic border faults, especially to their hanging limbs …and steep limbs of anticline-like uplifts'.

Geological-structural factors

The geological factors have also been analysed by [START_REF] Keefer | Landslides Caused by Earthquakes[END_REF][START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF] who concluded that any geological material with low geomechanical strength, be it soil or rock, may be susceptible to earthquake-induced slope instability. The low strength may be related to weak cementation, intense weathering or fracturing, high water saturation or poor compaction. Sensitive clays, sand and loess are particularly susceptible to seismic ground failure. With respect to the influence of the rock/sediment structure on seismic slope stability, [START_REF] Khazai | Evaluation of factors controlling earthquake-induced landslides caused by Chi-Chi earthquake and comparison with the Northridge and Loma Prieta events[END_REF] observed for landslides triggered by the 1999 Chi-Chi earthquake that 'in contrast to the shallow slides that typically occurred along joints and fractures oblique to the bedding/ foliation, the deep-seated failures appeared to be mostly sub parallel to bedding and/or foliation…' For giant landslides in China, [START_REF] Wen | Characteristics of rapid giant landslides in China[END_REF] noted that 'rainfall-induced landslides more often occurred in soils with slip surfaces along the soil-rock contacts, and in the stratified rocks with contrast in competency in which slip surfaces occurred along bedding planes, while earthquake-induced landslides were more prevalent in stratified competent rocks in which slip surfaces occurred along cross-bedding joints…' Most soft sediment landslides triggered by earthquakes in the Tien Shan seem to have failed along bedding contacts (Havenith et al., 2003a).

From these observations, no clear trend of local structural effects can be outlined -especially for seismic rock slope failure, it is not clear if cross-bedding joints or bedding contacts are more prone to the development of a sliding surface. Here, clearly more research based on structural geology mapping is needed.

Morphological factor

Earthquake-induced landslides may be triggered from any surface morphology -even within flat areas, such as lateral spreads, or from steep cliffs, such as rock falls.

Still, several particularities can be outlined. From observations after the 2005 Pakistan earthquake, [START_REF] Sato | Interpretation of landslide distribution triggered by the 2005 Northern Pakistan earthquake using SPOT5 imagery[END_REF] inferred that 'there was a slight trend that large landslides occurred on vertically convex slopes rather than on concave slopes; furthermore, large landslides occurred on steeper (30° and more) slopes than on gentler slopes'. This topographic effect was also revealed by [START_REF] Harp | Landslides Triggered by the October 8, 2005, Pakistan Earthquake and Associated Landslide-Dammed Reservoirs: USGS Open-file Report[END_REF] noting that '… several ridges near the top also are covered with fractures that are concentrated at the ridge crests and the summit'. They conclude that 'these fractures probably are associated with increased levels of shaking due to topographic amplification of the ground shaking'. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] noted that 'landslides induced by rainfall occurred mainly on steep slopes, whereas those induced by the Haiyuan Earthquake mainly occurred on relatively gentler slopes, indicative that the mechanisms of these two types of landslides are very different.'

From the above citations and our own experience of earthquake-induced landslides in the Tien Shan (see below), it can be concluded that mainly the surface curvature has an influence on seismic slope stability at a global scale; particularly, hillcrests, higher parts of slopes and convex surface morphologies are prone to seismic slope failure. The influence of slope angle on seismic slope stability is not clear; in some cases, especially in rocks, steeper slopes are more prone to instability; in others, especially in soft sediments, gentle slopes produce most of the mass movements, indicating that the combined effect of slope and geology has to be taken into consideration. Similarly the influence of the slope aspect on slope stability is closely connected to local environmental and tectonic conditions. [START_REF] Nadim | Global landslide and avalanche hotspots[END_REF] assessed landslide and avalanche occurrence probabilities worldwide on the basis of morphological, geological, meteorological and seismological data. They clearly showed that all landslide hotspots are located in seismically active mountain ranges. For Central Asia (Fig. 2), they estimate that global landslide hazard can be rated as medium to very high. They further noted that some areas in Tajikistan are marked by highest mortality risk due to landslides.

Case histories from Central Asia compared with events in China and Peru

The following case histories document the landslide hazard and risk triggered by earthquakes in the Tien Shan and the Pamir Mountains. A comparison will be made with the 1920 Haiyuan (China) and 1970 Peru events to outline the most important factors contributing to landslide hazard and risk in Central Asia.

Case histories from Central Asia

The Kemin earthquake, 1911

The Kemin Ms = 8.2 earthquake of 1911 (January 3) is one of the strongest events ever recorded in the Tien Shan; it was first analysed by [START_REF] Bogdanovich | Earthquake of the 4 January 1911 in the northern districts of the Tien Shan[END_REF]. The earthquake caused extensive landsliding along the activated fault segments over a length of 200 km. The largest mass movements were two rockslides, one within the Kemin valley and the other north of the lake Issyk-Kul. The first rock avalanche (about 15 10 6 m3) made of limestone material occurred along the activated Chon Kemin fault at about 60 km W of the epicentre, and is known to have buried a village of yourts with 38 inhabitants. The second 'Ananevo' rockslide located in the north of lake Issyk Kul (at some 80 km east of the presumed epicentre) is one of the most prominent features produced by the Kemin earthquake [START_REF] Havenith | Site effects analysis around the seismically induced Ananevo rockslide, Kyrgyzstan[END_REF], see Fig. 3). Failure took place at the southern end of a mountain ridge, just above the discontinuous Chon Aksu fault also activated by the 1911 Kemin earthquake. According to [START_REF] Delvaux | Landslides and surface breaks of the 1911 Ms 8.2 Kemin earthquake, Kyrgyzstan[END_REF], this section of the Chon Aksu fault is a thrust gently dipping towards the northeast into the collapsed slope. Evidence of the presence of the fault is the related scarp with a height of 1 m at 3 km WNW of the site increasing up to almost 10 m at 12 km to the WNW. On the site itself, outcrops at the foot of the southwest-oriented slope show particularly disintegrated and weathered granitic rocks within a 100-200 m thick fault zone.

The Sarez earthquake, 1911

The Sarez earthquake, Ms=7.6, struck the central Pamir Mountains, Tajikistan, on February 18, 1911. Such an earthquake is likely to have triggered hundreds or thousands of mass movements, but only one is well documented: the giant Usoi rockslide (Fig. 4), which fell from a 4500 m high mountain down to an elevation of 2,700 m in the valley [START_REF] Schuster | Usoi Landslide Dam and Lake Sarez, Pamir Mountains, Tajikistan[END_REF]. This rockslide has formed a dam with a volume of about 2 10 9 m 3 on Murgab River. According to [START_REF] Schuster | Usoi Landslide Dam and Lake Sarez, Pamir Mountains, Tajikistan[END_REF], the location of the slide is related to 'a high degree of rock fracturing from previous tectonic activity…a major thrust fault with an unfavourable orientation … and… a series of intensively sheared zones forming geometric setting for a typical wedge failure.' Behind this 600 m high natural dam (the highest dam in the world), Lake Sarez and the smaller Lake Shadau had been impounded, the first one with a maximum depth of 500.

Various scenarios consider the risk related to the failure of the rockslide dam due to internal erosion or overtopping as well as to a flood wave induced by the impact of mass movement into Lake Sarez. Those scenarios are discussed by [START_REF] Schuster | Usoi Landslide Dam and Lake Sarez, Pamir Mountains, Tajikistan[END_REF] and [START_REF] Risley | Usoi Dam Wave Overtopping and Flood Routing in the Bartang and Panj Rivers, Tajikistan[END_REF] -the worst-case scenario flood wave could affect more than 5 million people living in the Amu Darya river basin.

The Khait earthquake, 1949

According to [START_REF] Leonov | The Khait, 1949 earthquake and geological conditions of its origin[END_REF], [START_REF] Solonenko | Scars on the Earth's face[END_REF] and [START_REF] Gubin | Patterns of seismic manifestations of the Tajikistan territory (geology and seismicity)[END_REF], the M=7.4 Khait earthquake that struck Northern Tajikistan on July 10, 1949, produced one of the most destructive earthquake-triggered landslide events in human history. Though, the western world knows relatively little about it -probably because most information has been published in Russian. First, a massive rock avalanche had buried the villages of Khait & Kusurak with up to one thousand inhabitants (Fig. 5); the exact number of fatalities will never be known since 'during the formidable rule of Joseph Stalin, information about accidents and natural catastrophes was suppressed unless special permission was granted' [START_REF] Yablokov | The Tragedy of Khait: A Natural Disaster in Tajikistan[END_REF]. This rock avalanche had been triggered from Borgulchak mountain at an altitude of about 2950 m and travelled more than 6 km before reaching the inhabited valley at an altitude of 1550 m. The volume was initially estimated to more than 200 10 6 m 3 [START_REF] Leonov | The Khait, 1949 earthquake and geological conditions of its origin[END_REF]. However, more recent investigations by [START_REF] Evans | Landslides triggered by the 1949 Khait Earthquake, Tien Shan, Tajikistan[END_REF] indicated that the total volume would be much lower, of about 75 10 6 m 3 . [START_REF] Evans | Landslides triggered by the 1949 Khait Earthquake, Tien Shan, Tajikistan[END_REF] also observed that a significant part of the mass movement was made of loess, which probably contributed to the mobility of the initial rockslide.

Second, [START_REF] Evans | Landslides triggered by the 1949 Khait Earthquake, Tien Shan, Tajikistan[END_REF] indicate that in the Yasman valley opposite to the Khait rock avalanche, hundreds of loess earth-slides coalesced to form one massive earthflow, which is believed to have buried about 20 villages. In total, the Khait rock avalanche as well as the Yasman loess earth-flows are likely to have killed more than 4000 people during the 1949 event.

In addition to the catastrophic impacts, Russian geologists described also the general conditions of the earthquake-triggered slope failures. For instance, [START_REF] Leonov | The Khait, 1949 earthquake and geological conditions of its origin[END_REF] wrote (translated from the Russian original): '… involved are also amplification effects that can explain landsliding far from the epicentre…' This observation had already been pointed out above.

The Gissar earthquake, 1989

South of Dushanbe, in Gissar, Tajikistan, a Ms=5.5 earthquake on January 23, 1989 had triggered a series of earth-flows in loess. At least 200 people were killed and hundreds of houses were buried. According to [START_REF] Ishihara | Liquefaction-induced flow slide in the collapsible deposit in the Soviet Tajik[END_REF], those slides were all related to extensive liquefaction, which had developed for a horizontal acceleration of about 0.15g. [START_REF] Ishihara | Liquefaction-induced flow slide in the collapsible deposit in the Soviet Tajik[END_REF] associated the liquefaction to the 'collapsible nature' of the highly porous loess material (a silt-sized deposit with an average content of clay of 15 % and a low plasticity).

The largest landslide, called 'Okuli' (Fig. 6), had an estimated volume of 20 10 6 m 3 . [START_REF] Ishihara | Failure of Slopes and Soil Property Characterisation[END_REF] indicated that 'at least two slides seem to have been triggered independently from the hillsides on the north, which then merged into the main stream of the mudflow.' The sliding surface of most landslides was located at a depth of about 15 m within the saturated part of the 30 m thick loess deposits. [START_REF] Ishihara | Liquefaction-induced flow slide in the collapsible deposit in the Soviet Tajik[END_REF] also noted that the scarps of many landslides were located along a water channel installed on the shoulder of the hills. They assumed that 'water in the channel had been infiltrating in the loess over years leading to final failure during earthquake due to liquefaction of water-bearing loess layer'. This is supported by their observation of muddy water oozing from the earth-flow.

The Suusamyr earthquake, 1992

The most recent large seismic event hitting Central Asian mountain regions was the Ms=7.3 Suusamyr earthquake on August 19, 1992, triggering various types of ground failures in the Northern-Central Tien Shan [START_REF] Bogachkin | The Structure of 1992 Susamyr Earthquake Source Based on Its Geological and Seismological Manifestations[END_REF].

Most of the 50 people killed in the remote areas were victims of mass movements. [START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF] described a series of ground failures: sagging of mountain slopes, rockfalls, landslides, soil avalanches and flows, mud/debris flows, and also a great variety of gravitation cracks. Extensive ground failures could be observed along the crest and southern slope of the Chet-Korumdy ridge -here, most landslides had developed from previously existing ground instabilities (top left part of Fig. 7).

Most of the ground and slope failures spread over 4000 km 2 around the Suusamyr basin and the neighbouring mountain ranges were relatively small (less than 10 6 m 3 ). A map presenting all detected landslides in the Suusamyr region as well as ground failures induced by the Suusamyr earthquake is presented in Fig. 7 (modified from [START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF].

Only one large rockslide, the Belaldy rock avalanche, occurred on the southern slopes of the Suusamyr range [START_REF] Bogachkin | The Structure of 1992 Susamyr Earthquake Source Based on Its Geological and Seismological Manifestations[END_REF][START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF]. It has covered a shepherd's family and a flock of sheep. The situation before and after the earthquake of the rockslide site is shown in Fig. 8. This mass movement had formed a dam on Jalpaksu River with a thickness of about 100 m, a width of 700 m, and volume of more than 40 10 6 m 3 . Behind the dam two small lakes were impounded (with an area of 200-300 m 2 in September 1992). In less than a year, the water level had increased enough to induce partial failure of the dam [START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF]. This 3.1.6. The Kainama earth-flow -a delayed effect of small regional earthquakes?

The Kainama earth-flow (220 000 m 3 ) developed on April 26, 2004, had caused the destruction of 12 houses and the death of 33 people (64 families became homeless) south of the Fergana Basin (location in Fig. 1). This landslide had formed within the loess layer and developed into a very rapid flow with a long runout. Fig. 9 shows that, in 2001, no clear sign of instability could be seen. In spring 2003, several cracks appeared on the upper part of the slope.

The main failure of 2004 April was preceded by an increased seismic activity: on 2004 March 26, an earthquake of Ms=4.7 occurred 40 km SW of the Kainama site (PGA at the site ~ 0.05 g). Two other smaller earthquakes (Ms=4.2) were registered some 50 km NW of Kainama on April 8 and 9. New fractures had been observed after these earthquakes. The delay of massive slope failure after the earthquakes is likely to be related to changes of the local environmental conditions. At the end of March the mountains were still covered by snow -and the groundwater level was low. Snowmelt and spring rains in April caused a rapid increase of groundwater level -probably enhanced by rapid water infiltration through the new fractures induced by the earthquakes.

To confirm the important role of this process-sequence for development of many landslides in seismic areas, numerical modelling studies are being undertaken. Preliminary results had been published in [START_REF] Danneels | Geophysical investigation and numerical modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)[END_REF].

The 1920 Haiyuan (China) and 1970 Peru events

As shown previously, earth-flows in loess deposits and rock-debris avalanches proved to be the most catastrophic mass movements in Central Asian mountain regions. Therefore, the 1920 Haiyuan and 1970 Peru earthquakes were selected for comparison since they are known to have triggered, respectively, the most disastrous loess earth-flows and the most catastrophic single rock-ice avalanche.

The Haiyuan or Gansu earthquake, 1920

On December 16, 1920, a M=8.5 earthquake occurred near Ganyan Chi, Haiyuan County of the Ningxia Hui Autonomous Region in China [START_REF] Zhang | Geological Disasters in Loess Areas during the 1920 Haiyuan Earthquake, China[END_REF]. Several hundreds of thousands of houses collapsed and officially 234117 people died. [START_REF] Zhang | Geological Disasters in Loess Areas during the 1920 Haiyuan Earthquake, China[END_REF] noticed that particularly high intensities were recorded over areas covered by thick loess deposits: '…areas with intensity of 8 … here the damage caused by the slides was more serious than the primary ones caused by the quake. Based on field survey, abnormal 9 to 10 intensities were recorded here'. [START_REF] Zhang | Geological Disasters in Loess Areas during the 1920 Haiyuan Earthquake, China[END_REF] added that 'these landslides were not only controlled by the intensity of the earthquake, but by the structure of the subsoil'. It should be noticed that such an intensity of 8 (on Chinese Seismic Intensity Scale, CSIS -comparable to the European Macroseismic Scale, EMS-98) was recorded over 50000 km 2 [START_REF] Zhang | Geological Disasters in Loess Areas during the 1920 Haiyuan Earthquake, China[END_REF]. For comparison [START_REF] Zhang | Geological Disasters in Loess Areas during the 1920 Haiyuan Earthquake, China[END_REF] noted also that '…in spite of the high intensity of the quake, individual slides were quite small, their density low in this mountainous area, thanks to the thin soil cover and the bedrock is often exposed.' In total, a surface area of more than 4000 km 2 was affected by landslides, which buried numerous villages. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] referring to [START_REF] Close | Where the mountains walked[END_REF], reported that about 100000 people were killed by landslides in loess deposits. Dangjiacha landslide (Fig. 10) was one of the most catastrophic mass movements triggered by the 1920 earthquake. The landslide formed a dam with a volume of about 15 10 6 m 3 . Behind the dam, the largest lake induced by the earthquake had been impounded. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] observed that loess earth-flows triggered by the Haiyuan earthquake had developed on relatively gentle slopes compared to those triggered by rainfall in the same region.

These observations highlight the particular susceptibility of loess areas to ground failure, such as it was clearly shown by [START_REF] Derbyshire | Landslide in the Thick Loess Terrain of North-West China[END_REF] analysing geological hazards affecting the loess plateau of China. The failure mechanisms of loess earth-flows and their connection with liquefaction phenomena will be analysed more in detail in the next section.

The Peru earthquake, 1970

On May 31, 1970, the M=7.7 Peru earthquake triggered one of the most catastrophic landslides that have ever occurred: the Nevado Huascaran rock-ice avalanche. This event is not only known for the large number of casualties it has caused, about 18000, but also for its geologically fascinating aspects [START_REF] Plafker | Geological aspects of the May 31, 1970, Peru earthquake[END_REF]. The huge mass of rock and ice with a volume of more than 50 10 6 m³ originated from the west face of the 6654 m high north peak of Nevado Huascaran at some 130 km east of the earthquake epicentre. The particularity of this debris avalanche is its long travel distance of about 16 km. Before reaching the villages of Yungay and Ranrahirca, the mass slid for more than 2 km over a glacier, filled the valley floor at the foot of the slope and then was channelled through a gorge. Just before the end of the gorge, the avalanche split into two lobes one moving on towards the village of Ranrahirca, one overtopping the 230 m high southern ridge of the gorge and continuing its way to Yungay village. Peak velocities of this rock avalanche were actually estimated at more than 100 km/h by [START_REF] Wiley | Dynamics of rockslides and rockfalls[END_REF] and even to about 300 km/h by [START_REF] Plafker | Geological aspects of the May 31, 1970, Peru earthquake[END_REF].

Preliminary conclusions based on the case histories

The Nevado Huascaran and the Khait mass movements show that volume, runout and speed are three important factors contributing to the impact potential of mass movements. The volume and runout of the Khait rock avalanche (40 10 6 m 3 , about 9 km) are somewhat smaller than for Nevado Huascaran rock-debris avalanche (>50 10 6 m 3 , and 16 km). Further, no ice and probably no (free) water were involved in the Khait rock avalanche, such as in the Nevado Huascaran mass movement favouring its fluidisation. However, according to Evans et al. (2007), significant masses of loess were entrained along the path of the Khait rock avalanche. The mobility of this loess outlined above is likely to have contributed to the speed of the mass movement. We believe that the Khait rock avalanche was travelling with a speed similar to the one of the Nevado Huascaran when it reached the valley. The high speed of the Khait rock avalanche is also mentioned in the following notes from [START_REF] Solonenko | Landslides and collapses in seismic zones and their prediction[END_REF]: '…Its rate was about 100 km/h… A powerful airwave went before the collapse. It broke constructions, uprooted trees and threw them down for hundreds of metres.'

The Khait rock avalanche is one of the largest (recent) runout mass movements in the Tien Shan. Generally, rockslides with a similar volume (e.g. Belaldy rock avalanche) hit the opposite valley flank and stop or move only a few hundreds of meters along the valley floor where they form a landslide dam. A debris flow developing from a dam breach may, however, have a very long runoutabout 20 km in the case of the partial Belaldy rockslide dam failure.

Similarly, loess earth-flows are known to have caused rapid and long runout mass movements. For instance, in the Dzhalal-Abad region, Fergana Valley, Kyrgyz Republic, loess earth-flows had travelled over 7 km in 1994 killing several tens of people.

Considering also the previous notes on geological disasters in loess deposits, we believe that earthquake and landslide hazards are particularly high in those regions of Central Asia, which are covered by several tens of meters of loess: the foothill regions of the Fergana Basin rim (Kyrgyz Republic and Tajikistan) and around the town of Dushanbe (Tajikistan) as well as mountain valleys covered by loess up to an altitude of 2000-2500 m.

However, a disaster such as the 1920 Haiyuan earthquake is not expected to hit any of those regions for two reasons: first, a M>7.5 earthquake is very unlikely to occur in these areas; second, the loess cover is significantly thinner than on the loess plateau of China where the thickness can reach 300 m [START_REF] Derbyshire | Landslide in the Thick Loess Terrain of North-West China[END_REF].

Considering the enormous impact potential of massive rockslides, such as Belaldy or Khait, it is important to assess their occurrence probability. This probability is closely related to the recurrence time of the triggering earthquake (actually, only very few massive non-seismic rock avalanches are known from the Tien Shan) -but also other, climatic, aspects have to be considered as shown below.

First, for the Suusamyr region, it can be estimated according to the earthquake statistics presented by [START_REF] Abdrakhmatov | Probabilistic PGA and Arias Intensity maps of Kyrgyzstan (Central Asia)[END_REF] that the 1992 earthquake has a 500-year return period. Therefore, in near future, a similar earthquake -and a related rock avalanche such as Belaldy -is not expected to hit the same region. However, for the entire Tien Shan and Northern Pamir region, the analysis of [START_REF] Abdrakhmatov | Probabilistic PGA and Arias Intensity maps of Kyrgyzstan (Central Asia)[END_REF] showed that a return period of less than 20 years can be estimated for a M≥7 earthquake -able to trigger massive rockslides. Considering that the last M≥7 earthquake occurred in 1992, a rough computation of conditional probability indicates that there is a 90% chance to exceed a 7-magnitude event within the next 10 years. The probability to have such an earthquake -and related mass movements -seems to be highest (with a chance of 90% to exceed a M=7 earthquake within the next 10 years) along the Tien Shan -Pamir boundary region, where the last M≥7 earthquake was the Markansu event in 1974 close to the Tajik-Kyrgyz-Chinese border.

Recently on October 5, 2008, a M=6.6 earthquake hit this 3-border region and killed 75 people in Nura village, Kyrgyz Republic, which was entirely destroyed. A quick analysis of a SPOT 2.5 m resolution image acquired on October 16, 2008, eleven days after the earthquake showed that this earthquake had not triggered any major mass movements, besides a few rock falls in remote high mountain areas. We believe that the time of the earthquake after the dry summer season favoured slope stability. Also, we estimate that the Suusamyr earthquake in 1992 had triggered relatively few and small landslides due to its occurrence in August at the end of the dry summer season.

Though the 2008 Nura earthquake had been a major event, we think that the M≥7 earthquake along the Kyrgyz-Tajik border is still to come and most likely before 2020. According to previous observations, such an earthquake is most likely to trigger many large mass movements in early summer season (May-July), after snowmelt and spring rains.

Influence of seismic shaking and long-term effects

In the following, we will outline a series of dynamic processes involved in seismic ground and slope failure and long-term mass movement hazards.

Shaking effects

Shaking intensity, orientation and amplification

First, we will review some general observations of the influence of shaking on slope instability. The fact that earthquake-triggered landslides occur preferentially along activated faults and within the hanging wall is closely connected to the stronger shaking intensity in these parts close to the faults. [START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF] reviewed shaking thresholds for the three main mass movement classes. Using the Arias Intensity (computed on the basis of the integral of the square of acceleration of the recorded signal, see Arias 1970) as shaking unit, he showed that disrupted slides would have the lowest threshold of about 0.1 -0.15 m/s, coherent slides would be triggered for a shaking of more than 0.3-0.5 m/s and lateral spreads and flows for more than 0.5 m/s.

Second, we will analyse the influence of certain shaking particularities on slope stability. Considering the displacement of mass movements during the Wenchuan earthquake, [START_REF] Yin | Landslide hazards triggered by the 2008 Wenchuan earthquake[END_REF] concluded that for some types, which occurred very close to the fault, the vertical shaking component had significantly contributed to the failure. Actually, they observed that close to the fault ground motion records indicated a higher vertical than horizontal acceleration. It should be noticed that there are only few of such observations and that more research is needed to assess the effect of vertical shaking on slope failure. Another influence of shaking orientation has been pointed out by [START_REF] Wen | Characteristics of rapid giant landslides in China[END_REF] referring to [START_REF] Li | Relation between earthquakes and landslides and prediction on earthquake-induced landslides (in Chinese)[END_REF] who noticed that the largest landslides occur when ground shaking and slope aspect are in the same direction. To better quantify these observations, it would be necessary to investigate them by numerical simulations.

A very common observation already highlighted above is related to the topographic effects already mentioned above: seismic landslides are preferentially triggered from convex surface morphologies and hillcrests, which are also particularly prone to fracturing during earthquakes.

To better assess this effect at the Las Collinas landslide site, [START_REF] Crosta | Small fast-moving f low-like landslides in volcanic deposits: The 2001 Las Colinas Landslide (El Salvador)[END_REF] performed ambient noise measurements. Comparing the horizontal to vertical ratios on the Balsamo ridge from where the landslide was triggered with those at the bottom of the ridge, they observed an amplification of about 1.4 at the ridge.

We have extensively investigated this 'topographic' effect on seismic failure triggering (e.g. Havenith et al., 2003a;Bourdeau & Havenith, 2008) and observed that, generally, the morphological contribution to the amplification on ridge-tops is much smaller than the effect of the local geology. For rock slopes, [START_REF] Havenith | Site effects analysis around the seismically induced Ananevo rockslide, Kyrgyzstan[END_REF] showed that stronger and deeper weathering below convex surface morphologies reducing the elastic shear modulus of the material is the main factor favouring seismic ground motion amplification. For soft sediment sites, it was observed that a thicker cover of loess on top of slopes could also induce strong amplification [START_REF] Danneels | Geophysical investigation and numerical modelling of unstable slopes: case-study of Kainama (Kyrgyzstan)[END_REF]). We, therefore, suggest using the term 'site effects' well-known from the earthquake engineering approach to describe seismic amplification at the surface -site effects describe both wave focusing effects due to the morphology ('topographic effect') and due to the local geology (often called 'surface layer amplification'). [START_REF] Jurko | Hiroshi Fukuoka Study on seismic behavior of nonplastic silt by means of ringshear apparatus[END_REF] proposed to use the term liquefaction only to describe a rapid loss of strength resulting from increased pore water pressure and reduced effective normal stress. [START_REF] Ishihara | Failure of Slopes and Soil Property Characterisation[END_REF] reanalysed the landslide event triggered in Gissar, Tajikistan, by a M=5.5 earthquake in 1989. He concluded that extensive liquefaction must have developed in the loess deposit in the gently sloping hilly terrain to produce such catastrophic earth-flows. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] related the high mobility -strongly contributing to the overall impact of the mass movements -of the loess earth-flows triggered by the Haiyuan earthquake in 1920 to liquefaction phenomena. Through geotechnical tests, they also proved that the reduction of shear resistance mainly results from the generation of pore water pressure.

Liquefaction and processes in rapid loess earthflows

Until the Gissar event, liquefaction was known to affect water-saturated sand deposits (due to the larger grain size of sand with respect to loess). And Ishihara (2002) considered that the liquefaction in Gissar was unique and had occurred unexpectedly in a windlaid deposit of silt in a semi-arid region. Now, we know that exactly the same mechanism had mobilised hundreds if not thousands of landslides during the Haiyuan earthquake in the Gansu Province, China. Actually, [START_REF] Jurko | Hiroshi Fukuoka Study on seismic behavior of nonplastic silt by means of ringshear apparatus[END_REF] showed that not only sandy but also weakly plastic silt containing some clay could exhibit liquefaction under saturated undrained cyclic loading conditions. [START_REF] Ishihara | Failure of Slopes and Soil Property Characterisation[END_REF] attributed the liquefaction of the loess deposits in Gissar to their collapsible nature and the high water saturation at depth, related to infiltration of irrigation water over many years. The low plasticity of the loess contributes to its liquefaction under seismic shaking and its development into an earth flow with runouts of several kilometres. Recently, [START_REF] Jurko | Hiroshi Fukuoka Study on seismic behavior of nonplastic silt by means of ringshear apparatus[END_REF] suggested using the plasticity index (difference between liquid and plastic limit) as a for estimating the liquefaction potential of clayey soil.

Investigating the phenomenon of liquefaction in clayey soils, [START_REF] Osipov | The Mechanism of Liquefaction of Clayey Soils (M124)[END_REF] showed that: 1) low plasticity kaolin-, illite-and bentonite-sand mixtures were very vulnerable to liquefaction; 2) an increase in bentonite content raised both the soil plasticity and its resistance to liquefaction; and 3) the bentonite-sand mixtures with a plasticity index larger than 15 (i.e. requires a large amount of water to turn from a plastic to a liquid behaviour) were resistant to liquefaction. [START_REF] Wang | Seismic Behavior of Saturated Sandy Soils: Case Study for the May 2003 Tsukidate Landslide in Japan[END_REF] studied the Tsukidate landslide in sandy soils triggered by an earthquake in 2003 in Japan. They showed that under undrained conditions seismic loading results in a certain amount of excess pore water pressure within the saturated sliding surface, and then leads to the failure of the slope. After failure, high excess pore water pressure was generated with increase of shear displacement -a phenomenon called 'sliding surface liquefaction' [START_REF] Sassa | Dynamic properties of earthquake-induced largescale rapid landslides within past landslide masses[END_REF]. This finally resulted in a significant reduction of the shear resistance and in rapid movement. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] showed that, during a cyclic ring shear test on a saturated loess specimen under undrained conditions, cyclic shear stress clearly induced increasing pore pressure (u1 in top left part of Fig. 11). At the moment of failure, a quick generation of high pore pressure was observed (u2 in Fig. 11). And the cyclic ring shear test on loess with natural water content confirmed that this quick generation resulted from the instant collapse of soil structure at failure. After failure, the steady state was reached, where shear displacement continued under constant effective stress and shear resistance (right part in Fig. 11). Tests with dry loess samples showed that shear displacement increased only during cyclic loading, no additional displacement was generated after the loading. [START_REF] Zhang | Study of the 1920 Haiyuan earthquake-induced landslides in loess (China)[END_REF] concluded that in a slope consisting of dry loess, displacement could be generated only during the earthquake, and no long runout landslide would occur.

Long-term effects

The traces of strong earthquakes in the form of fault scarps and mass movements may be well preserved in the local relief and even be used for paleo-seismic studies. [START_REF] Korjenkov | Long-Term Preservation of Paleoseismic Deformations as a Tool for Revealing Traces of Ancient Seismic Catastrophes (Example of the Chon-Kemin Valley, Kyrgyzstan)[END_REF] showed that some morphological effects of earthquakes in the Chilik-Kemin fault zone could be dated back to Holocene, Late Pleistocene and even Late-Middle Pleistocene through geological and geomorphologic correlations with the local, relative Pleistocene chronology of river terraces and glacial moraines. For the Suusamyr region, [START_REF] Korjenkov | Rock Avalanches and Landslides Formed in Result of Strong Suusamyr (1992, M = 7,4) Earthquake in the Northern Tien Shan. Test Structures for Mapping of Paleoseismic Deformations by Satellite Images[END_REF] could outline that several newly triggered landslides and gravitation cracks had formed within paleo-seismic mass movements. On the southern slope of Chet-Korumdy ridge he could define three different generations of surface deformations -the third one being related to the Suusamyr earthquake, while the two others are remnants of old events, most likely similar strong earthquakes. [START_REF] Nepop | Estimating magnitudes of prehistoric earthquakes from landslide data: first experience in southeastern Altai[END_REF] investigated large mass movements in the Altai Mountains. They found that the large mass movements leave the most persistent imprint on landforms and thus represent the longest period of seismic activity.

These studies show that earthquakes may have longlasting effects on the landscape, which can be used for paleo-seismological studies. Consequently, they also do have mid-term effects -some of which may have significant impact on the global hazard. Some mid-and long-term effects have clearly been outlined for the 1999 Chi-Chi and 2005 Kashmir earthquakes. [START_REF] Dadson | Earthquaketriggered increase in sediment delivery from an active mountain belt[END_REF] analysed the co-and post-seismic geomorphic impact of the 1999 Chi-Chi event in Taiwan. In addition to the 20000 landslides immediately triggered by the earthquake, they found that co-seismic weakening of substrate material had caused increased landsliding during subsequent typhoons. Further, they observed that most of the co-seismically produced landslide material was transported towards the rivers, and thus increased sediment concentration during the storms after the earthquake. [START_REF] Petley | Incipient Landslides in the Jhelum Valley, Pakistan Following the 8th October 2005 Earthquake[END_REF] observed that the Kashmir earthquake had produced a 'very large extent of slope cracking in areas within 5 km of the fault'. These cracks would represent the initial failure type of future landslides, which had not developed into massive failure due to the low groundwater level. And, indeed, the precipitation level during the months before the earthquake had been anomalously low. Further, they related the more intensive landslide activity during the 2006 snowmelt and monsoon seasons to the 'extensive fissuring produced during the earthquake'. [START_REF] Keefer | Earthquake-induced Landslides and Their Effects on Alluvial Fans[END_REF] also analysed the long-term effects of earthquakes outlining that large earthquakes may modify the characteristics of drainage basins. Erosion and transport of the landslide material may then finally result in creation of new alluvial fans, increasing also the potential of debris flows or water flows over time.

Conclusions

A series of case histories of earthquake-induced landslides in Central Asia have been presented. The review clearly pointed out that, in these regions, large rockslides and rapid earth-flows in loess deposits have the highest impact potential. Therefore, some comparisons have been made with worldwide known earthquakes events, which had triggered disastrous slope failures of similar type, in particular the 1920 Haiyuan earthquake in China and the 1970 Peru earthquake. The volume and the mobility (runout and speed) of the mass movements play an important role for related hazard and risk. In this regard, it is not surprising that the most disastrous mass movement known from Central Asia is a long runout rock avalanche of a volume of about 40 10 6 m 3 , the Khait rock avalanche, which is supposed to have reached a speed of more than 100 km/h. Note, several massive and rapid rockslides occurred also in remote areas of Central Asian regions, where nobody or only few persons had been killed (e.g. during the Kemin earthquake, 1911).

While most of these giant rockslides have been triggered by large magnitude seismic events (M ≥ 7) in Central Asian mountain regions, loess earth-flows may also be triggered by smaller earthquakes -or even by climatic factors alone. Here, we presented some examples of fatal loess landslides triggered directly by a M=5.5 earthquake in Tajikistan and one landslide, which had developed in loess deposits several weeks after a M=4.7 earthquake. The comparison with the Haiyuan earthquake event of 1920 showed that such loess landslides could be very disastrous.

For loess earth-flows, the high impact potential is, however, not only related to the volume and mobility of a single landslide -which are generally lower than for massive rock avalanches. Here, the high spatial and temporal occurrence probabilities clearly contribute to related risk. The 1989 Gissar earthquake case history has shown that also M=5.5 earthquakes are able to trigger numerous loess landslides. Such earthquakes occur almost every year in the Central Asian mountain regions -many of which are covered by several meters of loess, especially in the foothill areas. For comparison, it was shown that the return period of a M ≥ 7 earthquake in the Tien Shan and northern Pamir able to trigger massive rockslides is about 20 years.

The importance of mid-and long-term effects was outlined both for rockslides and loess landslides. Several case histories showed that one important -if not the most important -long-term consequence of massive rockslides can be the formation of a dam and the impoundment of a natural reservoir. Actually, the largest still existing rockslide dam on earth had formed in 1911 in the Pamir Mountains. The worst-case scenario flood wave triggered by dam failure could affect more than 5 million people living in the Amu Darya river basin. The 1992-1993 Belaldy rockslide case history also documents the risk due to dam formation; partial failure of the dam resulted in a 20 km long mud-and debris-flow, which caused significant damage downstream.

For loess landslides, it was shown that seismic ground motions must not necessarily be the final trigger, but could also be a preparatory factor of slope failure. Relatively weak seismic shaking (e.g. < 0.1 g) is able to produce ground fractures, but often without inducing a mass movement. However, these ground fractures can facilitate water infiltration and related increase of groundwater pressures, which could lead to slope instability.

In this regard, it was also shown that similar earthquakes may not necessarily trigger the same amount of landslides, due to different climatic conditions and groundwater level at the time of the earthquake: the M=6.6 Nura earthquake in 2008 triggered relatively few landslides due to the occurrence at the end of the dry summer season. However, we do not know yet if snowmelt and spring rains in 2009 have triggered any new landslides.

Finally, the case histories showed that related landslides were not only instantaneous effects of earthquakes -some had already developed before the seismic shock and some continued or started moving well after the shaking. To better assess the short-to long-term effects earthquakes on slopes, landslides need to be monitored by geophysical, seismological and geotechnical systems, coupled to multitemporal satellite imagery and numerical modeling of multi-event scenarios. In the frame of new projects on landslide problems in Central Asia, focus will be on the installation of such monitoring -modeling systems.

Figure 1 :

 1 Figure 1: Map of Tien Shan and Pamir Mountains in Central Asia (general map in upper left corner) with location of major faults and earthquakes (white filled circles show all recorded M>=7 earthquakes with the year of occurrence; the magnitude is indicated for analysed events); earthquake-triggered mass movements and investigated landslide sites are marked by stars with names in italic.

Figure 2 :

 2 Figure 2: Landslide hazard map of Central Asia and Middle East (from Nadim et al., 2006).

Figure 4 :

 4 Figure 4: Usoi rockslide scarp (left) and dam (front) with dammed Sarez lake (right), after Schuster & Alford (2004).

Figure 3 :

 3 Figure 3: Helicopter Photograph of the Ananevo rockslide (10-15 10 6 m 3 ). Scale is given by the horse-farm building (lower left corner) of roughly 60 by 60 m.

Figure 5 :

 5 Figure 5: Khait rock avalanche; view towards the East from Yasman valley (colour version of photograph of 2005 provided by A. Ischuk, published in Evans et al., 2009).

Figure 6 :

 6 Figure 6: Okuli loess earth-flow. (photographs by Ishihara, 2002).

Figure 7 :

 7 Figure 7: Map of all detected landslides in the Suusamyr region (red) and ground failures triggered by the Suusamyr earthquake (modified from Korjenkov et al., 2004 -circle: M=7.3 epicentre; black lines with triangle: 1992 fault scarps; crosses: rockslides and landslides; stars: mud eruptions; grey bars: ground and slope fractures, black dots: rock falls).

Figure

  Figure 8: The Belaldy rock avalanche. A) Aerial photograph of the site acquired in 1980 (left), before the 1992 Suusamyr earthquake and space image of 1993 (right), after the earthquake. B) Photograph of the rock avalanche (scarp, behind, and dam, in front) in 2007.

Figure

  Figure 9: Evolution of the Kainama landslide from 2001 (ASTER satellite image, left), to 2003 (SPOT image, middle) and 2004 (SPOT image, right).

Figure 10 :

 10 Figure 10: Dangjiacha landslide (a) and its location (b), after Zhang & Wang (2007).

Figure 11 :

 11 Figure 11: Cyclic loading tests applied to saturated (left) and dry (right) loess samples (after Zhang & Wang, 2007).

Table 1 .

 1 Investigated landslide-triggering earthquakes in the Tien Shan and Pamir.

	Earthquake	Year	Rockslides	Landslides in soft sediments/ loess
	M=8.2 Kemin, Kyrgyzstan	1911	Chon-Kemin and Ananevo > 10 10 6 m 3 Several small landslides
	M=7.6 Sarez, Tajikistan	1911	Usoi ~ 2 10 9 m 3	Not reported
	M=7.4 Khait, Tajikistan	1949	Khait ~ 75 10 6 m 3	Yasman loess earth-flow
	M=5.5 Gisar, Tajikistan	1989	none	Okuli loess earth-flow and other loess slides
	M=7.3 Suusamyr, Kyrgyzstan	1992	Belaldy ~ 40 10 6 m 3	Chet-Korumdy debris-slides


Arn Arn

Arn

Sondes Fkiri
email: sondesfkiri@gmail.com

Touhami Rzigui
email: rziguitouhami@gmail.com

Hanene Ghazghazi
email: hanene8116@yahoo.fr

Larbi M Khouja
email: khoujalarbi15@gmail.com

Abelhamid Khaldi
email: khalditn@yahoo.fr

Frédéric Guibal
email: frederic.guibal@imbe.fr

Zouheir Nasr
email: zouheirnasr84@gmail.com

Ecotype effects on photosynthesis performance using A/PFFD Ecotype effects on photosynthesis performance using A/PFFD Ecotype effects on photosynthesis performance using A/PFFD Ecotype effects on photosynthesis performance using A/PFFD among among among among P P P Pinus inus inus inus nigra nigra nigra nigra

Keywords: light curves, net photosynthesis, P. nigra Arn, provenance

This study aimed to provide insights on intraspecific variability of photosynthesis performance of 19 provenances of black pine planted in a common garden. The experiment was conducted in an experimental trial located at Souiniet (the southern limit of its range) Photosynthetic capacity characterized by lightsaturated net photosynthetic rates, associated light compensation points and apparent quantum yield was monitored by measuring the response of leaf gas exchange to light levels. Amax was the highest in provenances Puget Theniers (nigra ssp), Saint-Guilhem (salzmanni ssp), Marghese and les barres (laricio ssp). The lowest value was recorded in Olette of the subspecies salzmanni. Needles from two provenances Crimea (pallasiana ssp) and Les Barres (ssp laricio) revealed the highest apparent quantum yield (ɸ), followed by Brougatlès Ales (salzmanni ssp), Trenta Coste (ssp laricio), Les barres and Puget Theniers (nigra ssp). The lowest apparent quantum Yield was recorded in Laricio subspecies (Cosenza; Les barres and Bois frerot). The highest value of dark respiration (Rd) was shown in provenance Les barres (laricio ssp), while Grancia and Tavola of the laricio subspecies reported the lowest one. Provenances Tavola (laricio ssp) and Puget Theniers (nigra ssp) exhibited the highest LCP. The provenance Crimée (pallasiana ssp) and Aspromonto (laricio ssp) recorded the lowest values. The maximum values of photosynthesis are positively correlated with the total chlorophyll contents and Leaf Mass area. Our study illustrates that Photosynthesis performance showed a difference between 19 provenances of black pine; it seems that black pine photosynthetic performance is eco-typical independent.

Introduction Introduction Introduction Introduction

Adaptation and phenotypic plasticity are two natural processes that trees and forests have at their disposal to cope with climate change [START_REF] Sow | Epigenetics in forest trees: state of the art and potential implications for breeding and management in a context of climate change[END_REF][START_REF] Diamond | Physiological adaptation to cities as a proxy to forecast global-scale responses to climate change[END_REF]. The short-term response of forests is based on phenotypic plasticity and the exploitation of existing adaptive diversity, whereas the longterm response is based on the genetic evolution of adaptive traits through selection (Lefèvre et al., 2010).

The process of adaptation to novel environmental conditions can occur via two mechanisms: (1) the expression of phenotypic plasticity, and (2) evolution via selection for particular phenotypes, resulting in the modification of genetic variation in the population [START_REF] Fox | Beyond buying time: the role of plasticity in phenotypic adaptation to rapid environmental change[END_REF] The ability of forest trees to adapt to climate change is highly dependent on their genetic diversity and geographical origins [START_REF] Schaberg | Anthropogenic alterations of genetic diversity within tree populations: implications for forest ecosystem resilience[END_REF]Soto et al., 2010). Genetic diversity is essential to the adaptive capacity of tree populations and is it the midst of current concerns on the future of forest species because of the large and rapid selection pressures related to climate change are expected (Kremer et al., 2002). Adaptive genetic diversity is very high between forest species, between geographical origins of the same species and within each population [START_REF] Lefèvre | Les processus biologiques de réponse des arbres et forêts au changement climatique : adaptation et plasticité phénotypique[END_REF]. As compared to other groups, conifers have a very high genetic diversity (Hamrick, 1992), but the genetic diversity of pines is considered to be more "adaptive" than other groups.

Among pines, Pinus nigra is one of the most diverse species (Lee et al., 2002;Nkongolo et al., 2002). This collective species has been the object of several studies that have investigated the intraspecific variability of growth performance and responses to climate in order to select the best adapted provenances to future climate conditions [START_REF] Strumia | Dendroclimatic sensitivity of Pinus nigra Arnold in Austria[END_REF][START_REF] Köse | Tree-ring growth of Pinus nigra Arn. subsp. pallasiana under different climate conditions throughout western Anatolia[END_REF][START_REF] Levanic | A 323-year long reconstruction of drought for SW Romania based on black pine (Pinus nigra) tree-ring widths[END_REF][START_REF] Shishkova | Climate growth relationship of Pinus nigra tree-ring width chronology from the Rhodope Mountains, Bulgaria[END_REF]. The species P. nigra is known for its relatively high phenotypic and genetic diversity (Jagielska et al., 2007;Lucic et al., 2010;[START_REF] Seho | Growth analyses of four provenances of European Black Pine (Pinus nigra) growing on dry sites in southwest Germany (Baden-Wuerttemberg)[END_REF][START_REF] Giovannelli | A new set of nuclear microsatellites for an ecologically and economically important conifer: the European black pine (Pinus nigra Arn.)[END_REF]). Varelides et al. (2001) had shown differences in growth between seventeen provenances of P. nigra from Greece, Turkey, Corsica and Calabria with significant interactions with various soil types in three sites in northern Greece. Furthermore, according to [START_REF] Kreyling | Cold hardiness of Pinus nigra Arnold as in uenced by geographic origin, warming, and extreme summer drought[END_REF], the cold resistance of P. nigra was found to be different between the provenances of cold regions that have shown a higher level of resilience. A study conducted on anatomical variables of the wood interested in the origins of Pinus nigra Arn. subsp. salzmanni has highlighted the adaptive nature of the wood anatomy of this species. (Esteban et al., 2011). Seedlings from six provenances of P. nigra that were exposed to the drought and warming over two years have shown that the origins of P. nigra differ greatly in their performance, while exhibiting a uniform sensitivity to the drought and local average temperature [START_REF] Thiel | Uniform drought and warming responses in Pinus nigra provenances despite speci c overall performances[END_REF]. Growth analyses from four black pine provenances (Austria, Bosnia, France (Corsica) and Italy) on dry sites of southwestern Germany revealed that the behaviour of the Corsican provenance differs from the three other sources [START_REF] Seho | Growth analyses of four provenances of European Black Pine (Pinus nigra) growing on dry sites in southwest Germany (Baden-Wuerttemberg)[END_REF].

This species is distinguished by high genetic diversity and high anatomical, morphological, and physiological variability (Isajev et al., 2004;Giovanelli et al., 2018). As such, it provides a suitable model for studying intraspecific diversity in responses to environmental change.

Genetic adaptation may be assessed in comparative plantations that are experimental sites in which species or several genetic units of the same species (geographical origins, families, and clones) grown under the same environmental conditions. This study was carried out in a comparative plantation in the southern limit of its range, which allows in particular, testing the existence of genetic differences between geographical origins. As environmental variations are controlled in a common garden, the differences observed in the expression of a given trait (the phenotype) are due to the genetic variability that exists between the different genotypes being compared. Some phenotypic traits can be well differentiated while others exhibit little difference.

The main objective of this study was to evaluate the in situ intraspecific variability of photosynthesis performance across black pine populations from different localities in the world. In another way, we investigated whether habitat of origin has any effect on photosynthetic acclimation. For this purpose, 19 provenances of black pine planted on the common garden in the southern limit of its range were used.

Materials and Methods

Materials and Methods

Materials and Methods

Materials and Methods

Study site

The Souiniet common garden (36°48′N, 8°48′E, 255 m, 492 m) was established in 1964 and characterised by a cold and humid climate, The mean annual temperature is 15.6 °C, the hottest month is July (31 °C) and the coldest one is January (4.4 °C). The soil is a balanced combination of loam, sand and clay.

Each provenance is represented by 21 trees, and the trees are 3 m apart. The understory vegetation is dominated by Erica scoparia L. and Halimium halimifolium (L.) Willk. Nineteen provenances (399 seedlings) of black pine (Pinus nigra Arn.) from France, Spain, Italy, Bulgaria, Russia and Turkey were planted in experimental trials under the same ecological conditions. The geographical origin of the provenances is shown in Table 1.

Table 1. Table 1. Table 1

Gas exchange measurements

The photosynthetic response of leaf needles to different levels of photosynthetic photon flux density (PPFD) was measured at ambient CO2 concentration (400 ppm) with an open infrared gas analysis system (Li-Cor 6400-40 equipped with a red-blue LED source; Li-Cor Inc., Lincoln, NE, USA). Light response curves were measured for attached leaves at 25 °C at an airflow rate of 300 cm 3 min -1 . The vapor pressure deficit was kept at 1.2 ± 0.2 kPa. Needles were allowed to reach a steady-state at an incident light level of 1200 µmol m -2 s - 1 PAR. We then changed the PPFD, and net photosynthesis (An) was recorded at each PPFD level once it became stable. Stomatal conductance (gs) and transpiration (E) were also recorded concurrently. Instantaneous water use-efficiency (WUE) was calculated as An/E (µmol CO2 µmol -1 H2O). Photosynthetic capacity was estimated by light-saturated net photosynthetic rate (Amax) as determined by fitting An/PPFD curves using a three component exponential function (see Meng et al., 2014 -eqn. 1):

An=Amax (1-e-b * PPFD) + c
Where An is the net photosynthetic rate, and Amax is the maximum photosynthetic rate. For each light curve, the apparent quantum yield based on the incident light (Φ) was calculated as the initial slope at the 3 lowest PPFD values (between 0 and 100 µmol m -2 s -1 ). The light compensation point (LCP) was estimated from the x-axis intercepts.

Photosynthetic pigments

The same leaves used for the measurement of gas exchange were sampled for the assessment of the total content of chlorophyll and carotenoids. Leaf tissue of known area (measured using a leaf area meter, Portable Laser, Model Cl-202) was incubated in 80% acetone until all of the chlorophyll was visibly extracted. Spectrophotometer readings of the extracts were obtained at 750, 663, 645 and 453 nm to determine the chlorophyll a and b and total carotenoid contents using the equations of Porra et al. (1989) and Robbelen (1957).

Leaf mass area

Leaf mass per area (LMA) is an important leaf trait widely used for relating light capture to plant growth and carbon gain, it is calculated as the leaf dry mass per unit leaf area (Kattge et al., 2011).

Statistics

All experiments were repeated at least 3 times, and the mean values and standard errors of the data are shown. All ANOVA analyses were performed using the software package SigmaPlot® (Systat Software Inc., San Jose, CA, USA). Statistically significant differences at the 5% level were calculated with the Student's t-test.

Results

Results Results Results

Light response curve of photosynthesis

The light response curves of photosynthesis were similar in all provenances (Figure 1). The rate of net photosynthesis (An) of P. nigra increased rapidly with increasing light intensity (0 to 400).

Beyond 400 μmol m -2 s -1 , An becomes stable and therefore saturated. Gaz exchanges parameters are estimated from light intensity response curves (Table 2). The plateaus of these curves correspond to the maximum photosynthetic capacity (photosynthetic assimilation in saturating light, Amax). The apparent quantum yield (ɸ) estimated at the base of the incident light (PAR< 200 μmol m -2 s -1 ) provides information on the number of photons necessary for the fixation of a CO2 molecule. The light compensation point (LCP) corresponds to the light in which photosynthesis exactly compensates for respiration (zero balance).

The results obtained revealed that Amax, Rd, ɸ and LCP are significantly different between provenances (p <0.05) (Table 2). Amax varied between 7.925 and 1.9 μmol CO2 m-2 s-1. Amax is highest in provenances P6 (nigra ssp), P12 (salzmanni ssp), P20 and P19 (laricio ssp). The lowest value was recorded in P18 of the subspecies salzmanni. Needles from two provenances Crimea (P13) (pallasiana ssp) and Les Barres (P3) (ssp laricio) revealed the highest quantum yield (ɸ), followed by P1 (salzmanni ssp), P2, P19 (laricio ssp) and P6 (nigra ssp). On the other hand, the lowest ɸ was recorded in provenances P4, P11 and P5 (ssp laricio). Respiration (Rd) is highest in provenance P11 of the subspecies laricio var. corsicana, on the other hand P14 and P17 of the laricio subspecies recorded the weakest respiration. Provenances P17 (ssp laricio) and P6 (nigra ssp) exhibited the highest light compensation point (LCP). P13 (pallasiana ssp) and P15 (laricio ssp) recorded the lowest values.

Variations of gs, E and WUEi in response to PPFD

Transpiration (E) (Figure 2) and Stomatal conductance (gs) (Figure 2) increased as light intensity. However, a significant difference in gs and E responses as a function of PPFD was recorded between subspecies and provenances. Provenances P6 of the subspecies nigra, P14, p17 and P20 of the subspecies laricio and P12 of the subspecies salzmanni recorded the highest stomatal conductance and needle transpiration at light intensities above 1500 μmol m -2 s -1 . The lowest gs and E values for all applied light intensities were recorded in provenances P10, P15 and P3 of the laricio subspecies.

Table 2. Table 2. Table 2. Table 2. Light-saturated photosynthesis (Amax), light compensation point (LCP) and apparent quantum yield (Φ) in needles of Pinus nigra provenances grown under three light regimes Provenances Amax (µmol CO2 m -2 s -1 ) 6,666b 0,0089c -2,1kj 70hij P20 P20 P20 P20 7,925a 0,006ed -1,262e 66,33ij

ɸ (mol CO2 mol -1 photon) Rd (µmol m -2 s -1 ) LCP (µmol photons m -2 s -1 ) Figure 2.
Figure 3. Figure 3. Figure 3. Instantaneous water use efficiency (WUEi) was estimated by relating the net assimilation of photosynthesis (An) to transpiration. A remarkable increase in WUEi with increasing irradiance was observed. WUEi is completely saturated at light intensities <600 μmol m -2 s -1 for almost all provenances (Figure 4). Provenances P3, P11, P19, P13 and P12 are the most efficient in using water under saturated light.

Photosynthetic pigments

The analysis of variance of the chlorophyll pigments showed a highly significant difference between the 19 sources (P<0.0001). The needles from provenances P12, P8 and P19 have the highest content, while provenance P19 has the lowest total chlorophyll concentration (chl a+chl b). The carotenoid content was highest in P4, P5 and P13 and lowest in P17, P8 and P19 (Table 3).

(g/cm 2 ) P1 P1 P1 P1 1,41b 0,452gf 1,8617dc 0,284cd 3,113 e 0,153 e 1,84b P2 P2 P2 P2 0,41ih 1,33cd 1,679cd 0,137ef 0,308q 0,079l 0,83d P3 P3 P3 P3 0,812a 0,867e 1,6793cd 0,0596gh 0,663k 0,036o 1,05dc P4 P4 P4 P4 0,923efd 1,562ab 24855ab 0,509a 0,591n 0,205c 1,92b P5 P5 P5 P5 1,182bcd 0,319gh 1,5017de 0,343bc 3,698c 0,229b 0,97dc P6 P6 P6 P6 1,166bcd 0,769e 1,936dc 0,249d 1,515h 0,129h 2,48a P8 P8 P8 P8 0,745efg 1,235d 1,9807dc 0,0286h 0,603m 0,014q 1,06dc P9 P9 P9 P9 0,368ih 0,61f 0,9783f 0,146ef 0,603m 0,15f 0,99dc P10 P10 P10 P10 1,28bc 0,599f 1,8793dc 0,315c 2,137g 0,168d 1,4c P11 P11 P11 P11 0,5997fgh 0,93e 1,53cde 0,185ef 0,644l 0,121i 1,10dc P12 P12 P12 P12 0,6247efgh 1,473bc 2,0977bc 0,102fgh 0,424o 0,049n 1,08dc P13 P13 P13 P13 1,22bcd 0,375gh 1,5953cde 0,377b 3,251d 0,236a 2,16ab P14 P14 P14 P14 0,5697gh 0,599f 0,7933f 0,11fg 2,545f 0,139g 1,08dc P15 P15 P15 P15 0,8efg 1,206d 2,0057 0,576gh 0,663k 0,029p 1,10dc P16 P16 P16 P16 0,1837i 1,67ab 1,8537dc 0,104fgh 0,11l 0,056m 1,12dc P17 P17 P17 P17 1,8147a 0,279gh 2,094bc 0,0603gh 6,493a 0,29p 1,24dc P18 P18 P18 P18 0,4887gh 1,163d 1,652cd 0,188 e 0,42p 0,114j 0,98dc P19 P19 P19 P19 1,124bcd 1,43bc 2,554ab 0,033gh 0,786j 0,013r 1,40dc P20 P20 P20 P20 0,9507ecd 0,205h 1,155ef 0,105fgh 4,637b 0,091k 1,30dc
The values shown represent the mean of at least three replicates with standard errors.

Discussion

Discussion Discussion Discussion

The efficiency of carbon assimilation capacity as a function of photosynthetic photon flux density (PPFD) of black pine has been assessed. Several authors have emphasized the importance of photosynthetic performance as an element of selection (Valladeras et al., 2010). [START_REF] Bassow | Intra-and inter-specific variation in canopy photosynthesis in a mixed deciduous forest[END_REF] mentioned that within the same forest, photosynthesis can vary greatly among species and within an individual tree. In our study, the variability of photosynthetic efficiency within Pinus nigra species planted in the same pedoclimatic conditions was assessed. High intraspecific variability in terms of photosynthesis capacity was found (p <0.05). These results demonstrated that the ecological origin of provenances determined their photosynthetic performance.

This variation was observed in individuals under the same environmental conditions, indicating a high degree of intrapopulation genotypic variability in black pine, as has been reported for other species. Indeed, Blaguer et al. (2001), from the analysis of the response in light of different populations of Q. coccifera from different origins, concluded the existence of an eco-typical difference and not phenotypic plasticity. In addition, several studies showed that the light curves differ between species and within the same species (Lambers et al., 2006;Aber et al., 2001, Lachapelle 2011;[START_REF] Huang | Rapid light-response curve of chlorophyll fluorescence in terrestrial plants: Relationship to CO2 Exchange among five woody and four fern species adapted to different light and water regimes[END_REF]. Using the photosynthesis-light curve, the parameters Amax, Rd, LCP and ɸ were estimated. Several studies have compared the photosynthetic performance of different species on the basis of these criteria (Leverenz et al., 1996;Sullivan et al., 1997;Evans et al., 2001;Tang et al., 2003;Hiroaki et al., 2012;Guzmán et al., 2013;Rzigui et al., 2015Guzmán et al., 2016;Yang et al., 2020). Leverenz (1995) showed that the variations in Amax between species were small compared to variations within a species. In this study, the maximum rate of photosynthesis (>1500 µmol de photons. m -2 . s -1 ) were reached by the four provenances Marghèse (P20) (laricio ssp), Les Barres (P19)(laricio ssp), Puget-Thénier (P6) (nigra ssp) and Saint-Guilhem (P12) (salzmanni ssp). The increase in photosynthesis as a function of light intensities is limited by the carboxylation capacity of Rubisco or by the metabolism of triosic phosphates (Sharkey, 1987;Harley et al., 1992;Yang et al., 2015). [START_REF] Chazdon | Determinants of photosynthetic capacity in six rainforest piper species[END_REF] showed, among Piper species, that Amax was strongly dependent on leaf nitrogen and on all descriptors of the light environment in the leaf microsite. In our study, the maximum values of photosynthesis (Amax) are positively correlated with the total chlorophyll contents of the species Pinus nigra (r 2 = 0.768). Leverenz (1987) showed that the photosynthetic rates of the needles of five conifers (Picea abies (L.), Picea glauca, Voss, Picea mariana Bsp, Picea sitchensis Carr., Pinus sylvestris L.) were strongly correlated with the amount of chlorophyll. Amax and LMA are positively correlated for the species P. nigra (r 2 =0.617). In the same context, Wright et al. (2004) showed that the maximum net photosynthesis rate (Amax), specific leaf area (LMA) covariate among themselves, for all 2548 species sampled across the planet. This relationship could derive from a greater contribution of mesophyllian tissues containing chloroplasts reported to the biomass [START_REF] Nouvellon | Within-stand and seasonal variations of specific leaf area in a clonal eucalyptus plantation in the Republic of Congo[END_REF]Wayka et al., 2012). Apparent quantum yield, the equivalent of moles of absorbed photons that are converted into moles of fixed CO2, was higher in provenances; Crimée, Les Barres, Brouzet-lès-Alès, Trenta, Barres suggesting that the efficiency of the Calvin cycle, in terms of the use of ATP and NADPH, is higher in the needles of these provenances compared to other ones (Jones, 1998;[START_REF] Bauerle | Leaf age and position effects on quantum yield and photosynthetic capacity in hemp crowns[END_REF]. Thus, this parameter of leaf photosynthesis has been shown efficiency in needles of these provenances in terms of carbon uptake.

The ability of a species to acclimate and adapt to environmental conditions is associated directly/indirectly with its ability to modulate photosynthesis and water vapor exchange (Ayuko et al., 2008;Dieleman and Meinen, 2008;Kruse et al., 2008). The WUEi is completely saturated at light intensities close to <600 μmol m -2 s -1 almost for all the origins of Pinus nigra. When the light is weak, gas exchange and therefore the WUEi depend on photosynthetic reactions limited to light, while, under high light intensities, The WUEi is mainly controlled by stomatal conductance (Lawson, 2009;Hummel et al., 2010;Eisenach et al., 2012;Lawson andBlatt, 2014, Fkiri et al., 2020). [START_REF] Cornic | Effect of dehydration and high light on photosynthesis of two C3 plants {Phaseolus vulgaris L. and Elatostema repens (Lour.) Hall f.)[END_REF] noted that heterogeneous stomatal closure caused a decrease in net photosynthesis at high PPFD and a decrease in the apparent quantum yield. Thus, high stomatal conductance and WUEi under limited photosynthetic conditions could be advantageous for provenance/species performance.

Conclusions Conclusions Conclusions Conclusions

In this study pattern of photosynthetic response to variations in photosynthetic photon flux densities was investigated. Results obtained showed that the photosynthetic performance is eco-typical controlled. Indeed, the nineteen provenances of P. nigra originate from various origins around the Mediterranean area planted under the same environmental conditions demonstrated a significant difference in terms of photosynthetic capacity. Therefore, these parameters taken from the light curve could be used in the selection of performance provenances. Thus, Provenances that show better photosynthetic performance are recommended for reforestation or afforestation in like conditions because they sequester much more carbon than others and therefore, they could be a suitable carbon reservoir.

Figure 1 .

 1 Figure 1.Figure 1.Figure 1.Figure 1. Light response curves: Net carbon assimilation (An) of attached needles measured at different PPFD levels in an atmosphere of 400 ppm CO2 and 25 °C from 4 sub-species

  Figure 1.Figure 1.Figure 1.Figure 1. Light response curves: Net carbon assimilation (An) of attached needles measured at different PPFD levels in an atmosphere of 400 ppm CO2 and 25 °C from 4 sub-species

  Figure 1.Figure 1.Figure 1.Figure 1. Light response curves: Net carbon assimilation (An) of attached needles measured at different PPFD levels in an atmosphere of 400 ppm CO2 and 25 °C from 4 sub-species

Figure 1 .

 1 Figure 1.Figure 1.Figure 1.Figure 1. Light response curves: Net carbon assimilation (An) of attached needles measured at different PPFD levels in an atmosphere of 400 ppm CO2 and 25 °C from 4 sub-species Values are means ± SE of at least three independent measurements.

  Figure 2.Figure 2.Figure 2.Figure 2. Response of stomatal conductance (gs), as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C

  Figure 2.Figure 2.Figure 2.Figure 2. Response of stomatal conductance (gs), as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C

Figure 2 .

 2 Figure 2.Figure 2.Figure 2.Figure 2. Response of stomatal conductance (gs), as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C Values are means ± SE of at least three independent measurements.

Figure 3 .

 3 Figure 3. Figure 3. Figure 3. Figure 3. Response of transpiration rate (E) as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C Values are means ± SE of at least three independent measurements.

  Figure 4.Figure 4.Figure 4.Figure 4. Response of gas exchange to light: instantaneous water use efficiency (WUEi) as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C

  Figure 4.Figure 4.Figure 4.Figure 4. Response of gas exchange to light: instantaneous water use efficiency (WUEi) as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C

  Figure 4.Figure 4.Figure 4.Figure 4. Response of gas exchange to light: instantaneous water use efficiency (WUEi) as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C

Figure 4 .

 4 Figure 4.Figure 4.Figure 4.Figure 4. Response of gas exchange to light: instantaneous water use efficiency (WUEi) as a function of PPFD in an atmosphere of 400 ppm CO2 and 25 °C Values are means ± SE of at least three independent measurements.

  T T T Ta a a ab b b bl l l le e e e 3 3 3 3. . . . Leaf pigments content: Chl a+b and total carotenoid concentrations per unit leaf area and chlorophyll a/b and carotenoids/total chlorophyll (Car/Chl)

Table 1 .

 1 . The Geographical origin for the sample populations of black pine (Pinus nigra Arn.)

	Provenances	Sub-species	Provenance	Country of origin
	P1	Pinus nigra salzmanni	Brougatles Ales	France
	P2	Pinus nigra calabrica	Trenta Coste	Italy
	P3	Pinus nigra calabrica	Les Barres	France
	P4	Pinus nigra calabrica	Cosenza	Italy
	P5	Pinus nigra corsicana	Bois frerot	France
	P6	Pinus nigra austriaca	Puget Theniers	France
	P8	Pinus nigra nigricana	Kustentil	Bulgaria
	P9	Pinus nigra pallasiana	Alaçam	Turkey
	P10	pinus nigra calabrica	Catanzaro	Italy
	P11	Pinus nigra corsicana	Les Barres	France
	P12	Pinus nigra salzmanni	Saint-Guilhem	France
	P13	Pinus nigra pallasiana	Crimée	Russia
	P14	Pinus nigra calabrica	Grancia	Italy
	P15	Pinus nigra calabrica	Aspromonto	Italy
	P16	Pinus nigra salzmanni	Cazorla	Spain
	P17	Pinus nigra calabrica	Tavola	Italy
	P18	Pinus nigra salzmonni	Olette	France
	P19	Pinus nigra calabrica	les Barres	France
	P20	Pinus nigra corsicana	Marghese	Corse

Acknowledgements Acknowledgements Acknowledgements Acknowledgements

This work was supported and funded by National Institute of Rural Engineering, Water and Forest.

1,485f 154,68b P6 P6 P6 P6 7,424a 0,0084c -0,413b 66,68ij P8 P8 P8 P8 6,218bc 0,0033fg -1,892ih 107,33d

Authors' Contributions Authors' Contributions Authors' Contributions Authors' Contributions

Methodology FS, RT and NZ; Supervision M.L K, KA and NZ; Validation NZ; Writing -original draft: FS; Writing -review and editing RT, GF, HG and SY.

All authors read and approved the final manuscript.

Ethical approval Ethical approval Ethical approval

Ethical approval (for researches involving animals or humans) Not applicable.

Conflict of Interests Conflict of Interests Conflict of Interests Conflict of Interests

The authors declare that there are no conflicts of interest related to this article.


Extrait de ma communication lors de la journée : les chantiers du Sophiapol

Paysans et domesticités : une réécriture de l'histoire de l'accumulation dite primitive Partout dans le monde, on assiste à une révolte des paysans qui sont victimes de l'accaparement de leurs terres. Cette situation pousse ces derniers de mener une lutte et de s'opposer afin de faire face à la logique prédatrice du capitalisme.

C'est dans ce sillage que s'inscrit la victoire historique remportée, en novembre 2021, par les paysans indiens1 face au gouvernement qui avait voté des réformes afin de priver ces derniers de leurs terres. Face à la détermination des paysans, le pouvoir politique en place se voit contraint de retirer les trois législations envisagées.

Cette situation au-delà de l'exemple concret de l'Inde ici convoqué, est perceptible sous diverses formes dans les contrées du monde. Cela peut s'expliquer, entre autres, par la volonté manifeste et continue du système capitaliste à vouloir sans cesse accaparer des richesses et à creuser davantage des inégalités. Cette situation d'expropriation et d'accaparement des richesses nous replonge sur la thèse marxienne de la genèse du capitalisme. A travers le concept de l'accumulation dite primitive ou initiale, Marx démontre les conditions de naissance et d'élaboration du système capitaliste.

L'usage du concept de l'accumulation dite primitive avait une double préoccupation qui se rejoigne et se complète. Il s'agissait d'une part une réponse apportée aux physiocrates dont Quesnay qui prônaient que l'origine du capitalisme obéit à un ordre naturel ; d'autre part, Adam Smith qui stipule, que l'enrichissement d'une nation, voire d'un pays, repose sur l'augmentation de la quantité de travail et l'amélioration de la productivité.

Contrairement à ces deux approches, Marx élabore une approche critique et globale de la genèse du capitalisme. En substance, chez Marx, la genèse du capitalisme s'est traduite à travers une exploitation des paysans, dépourvus des moyens de production par les détenteurs des capitaux et qui transforment ceux-là en ouvriers. Le mérite de Marx c'est d'avoir surtout rendu visible la violence qui s'avère être au coeur, voire au fondement du capitalisme.

Nous le savons cette thèse marxienne de la genèse du capitalisme a nourrit de nombreux débats dans les sciences sociales. A commencer par Rosa Luxemburg qui dans son ouvrage l'accumulation du capital remet en cause l'idée d'une simple et cohérente reproduction de l'accumulation. Pour Rosa Luxemburg, le capitalisme pour exister et survivre devra sortir de lui-même. Ainsi l'idée fondamentale qui structure son oeuvre est le concept de capitalisme du dehors. Ce qui veut dire que chez Luxemburg, la richesse ne provient pas uniquement et exclusivement du capitalisme lui-même. Par conséquent, il s'avère nécessaire que le capitalisme explore d'autres zones en dehors de lui-même.

On retrouve une réactualisation de cette thèse défendue par Luxemburg chez David Harvey dans son célèbre ouvrage : le nouvel impérialisme ( 2010) où il reprend de manière assez originale la thèse marxienne en la confrontant d'avec la critique formulée par Luxemburg. Cette double confrontation conduira Harvey à forger le concept : « accumulation par dépossession » qui désigne une concentration des richesses entre un nombre restreint de mains, les capitalistes en insistant sur le rôle que joue l'Etat et les institutions internationales.

De nombreux auteurs2 ont repris la thèse marxienne de l'accumulation dite primitive. Dans ce vaste champ des débats portant sur la thèse marxienne et de son implication, nous inscrivons notre propos dans les approches anthropologiques et féministes qui ont retenu notre attention. Il s'agira pour nous, en partant de ces deux approches de voir sous quelle forme se déploie le discours portant sur l'accumulation primitive.

En premier, l'approche anthropologique rendue célèbre par Claude Meillassoux3 , qui dans sa relecture du récit marxien de la naissance du capitalisme, met en avant le rôle qu'a joué la famille. De ce fait, Meillassoux démontre que le processus de transition du féodalisme au capitalisme doit être surtout étudié à partir des structures sociales, c'est-à-dire la reproduction de la force de travail au sein des familles. L'anthropologue français ajoute une deuxième exploitation dans la sphère de la reproduction qu'est la famille. Celle-ci prise au sens large et globale produit le travailleur qui s'articule ensuite aux différents modes de production classiques. S'y ajoute le rôle de la paysannerie dans la genèse du capitalisme. Nous savons chez Marx, les moments phares, voire déterminants de l'accumulation primitive sont l'expropriation des terres des paysans et la séparation de se dernier d'avec ses moyens de subsistances. A cette thèse marxienne, Meillassoux ajoute l'incorporation de la paysannerie dans l'impérialisme.

Cette critique va opérer un déplacement assez original de l'analyse des conditions de naissance et de développement du capitalisme tel que défendu par Marx.

La seconde renvoie aux théories féministes, comme celle de Silvia Federici , qui voit dans l'analyse marxienne de la genèse du capitalisme le fait d'avoir omis ,voire relégué au second plan le rôle joué par les femmes. En d'autres termes, les théories féministes reprochent à l'analyse marxienne de n'avoir pas trop, voire occulté l'apport des femmes dans la genèse du capitalisme.

Eu égard aux différentes révoltes de la paysannerie dans de nombreux pays, notamment dans les pays périphériques également appelés les pays du Tiers-Monde et le rôle du travail reproductif, l'apport des femmes dans l'accumulation du capital, il nous a semblait fort utile de se donner la tâche d'une réécriture de l'histoire de l'accumulation dite primitive.

Pour ce faire, nous proposerons au cours de ce travail une tentative d'intégrer domesticité et paysannerie dans une relecture de la thèse marxienne de la genèse du capitalisme. D1-Cela suppose de voir en anthropologie marxiste la place faite à la domesticité, à la paysannerie, Qu'en est-il ? Pour ce faire, nous partirons des pistes de recherche obtenues lors de la rédaction de notre mémoire de master qui évoque le thème ici proposé et enrichir notre bibliographie au fur et à mesure.

D2-Également se travail se donne la lourde tâche de relecture interne de ce passage sur l'accumulation primitive, eu égard à Marx et à ses continuations révolutionnaires. En d'autres termes, paysannerie et domesticité ont depuis les derniers écrits de Marx, sur le Mir et la révolution russe, remis en question une compréhension de l'histoire du capitalisme.

Voir Victoire historique des paysan•nes indien•nes -CONTRETEMPS.

Parmi ces auteurs entre autre qui ont relancé le débat portant sur la thèse marxienne de la genèse du capitalisme, nous pouvons évoquer l'apport de Rosa Luxemburg

Cf MEILLASSOUX Claude, Femmes, greniers et capitaux, Paris L'Harmattan, 1992. Et Anthropologie économique des Gouro de Côte d'Ivoire. De l'économie de subsistance à l'agriculture commerciale, Paris, EHESS, 2013. Ces deux ouvrages relancent le débat portant sur la reproduction de la force de travail.