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Peer Reviewed
See detailUnderstanding of the diversity of earthquake turbiditic flows in a single lake: the case of the Lake Hazar on the East Anatolian Fault
Lamair, Laura ULg; Hage, Sophie ULg; Hubert, Aurelia ULg et al

Poster (2014, August)

The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia ... [more ▼]

The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia collision zone. The East Anatolian Fault ruptured over most of its length during the 19th century in a series of magnitude ~7 earthquakes. During the 20th century this fault was less active with only two events of magnitude greater than 6. This absence of large earthquakes has resulted in relatively little attention being paid to the East Anatolian Fault compared to the North Anatolian Fault, which has ruptured during the last century in several earthquakes of Ms~7. To constrain the seismic history of the East Anatolian Fault in its central part, we focus on the Hazar Lake, occupying a 20 km long pull-apart basin. Short cores and long sedimentary cores were collected at three different sites to retrieve a paleoseismic record. Small correlative coarse-grained sedimentary events are identified in all cores. The age of the events is inferred combining radiocarbon and radionuclide (137 Cs and 210Pb) dating. We present here detailed analyses of three sedimentary events assigned respectively to the historical earthquakes occurring in 1789, 1513-1514, 1285. The source of the sedimentary events is different at the three sites. We combine X-ray imagery, magnetic susceptibility, grain-size and XRF measurements with thin section analysis to investigate the nature of sedimentary events. The analyses show first that the three sedimentary events are different. The magnitude of the terrigenous signal varies significantly. Second the correlative events have a different expression at the three sites. So each site has a different and specific sensitivity. In particular, an individual event can be composed of several coarse-grained sub-events of different magnitude with a time lapse in between greater than a week. The latter is reveals by the presence of bioturbation in particular by chironomids in individual thin sand layers. Thin section also shows that subevents are gradded. Each coarse-grained layer is thus a separated turbiditic flow. The site with the highest sensitivity is the one located near the near-shore steep submarine southern slopes overhanged by the steep subaerial slopes of the Hazar Mountains. The rivers draining the Hazar Mountains are ephemeral and provide a restricted sedimentary supply. In addition, seismic reflection data show that the submarine slopes do not to accumulate a significant sedimentary load. However on these steep slopes, an earthquake intensity of 6 or less is enough to trigger a slope failure and the associated turbiditic flow. We conclude that the different sub-events at this site may record a complete earthquake sequence, i.e the main-shock and its foreshocks and aftershocks. [less ▲]

Detailed reference viewed: 46 (5 ULg)
Peer Reviewed
See detailHARBIYE AQUEDUCT: A RECORD OF PAST EARTHQUAKES
Lamair, Laura ULg; Degée, Hervé ULg; Hubert, Aurelia ULg et al

Poster (2014, August)

This paper presents a detailed analysis of Harbiye aqueduct (Hatay, Turkey). The region is situated at the junction of two major faults (East Anatolian fault and the Dead Sea fault) and is well known for ... [more ▼]

This paper presents a detailed analysis of Harbiye aqueduct (Hatay, Turkey). The region is situated at the junction of two major faults (East Anatolian fault and the Dead Sea fault) and is well known for his important historic seismicity. The aqueduct is located close to Antioch on the Orontes (known as Antakya). The city was founded in the third century BC. Harbiye aqueduct is characterized by different stages of building (Benjelloun et al., submitted). A phase is dated to Caligula period. After the 37 AD earthquake, the aqueduct was rebuilt. We noticed the presence of two dissociated travertine and a changing of masonry material. We also observed several damages and repair structures dating from Roman time. We assume that our observations are the results of one or more earthquakes. Since the construction of the aqueduct, historical seismic records mention 13 earthquakes that provoked severe damages in the city of Antioch (Guidoboni et al. 1994, Al-Tarazi, 1999, Över et al. 2002). The last one occurred in 1872 (M=7.2). In order to test our hypothesis, we modelled the structure of the aqueduct by using FineLg, a software developed at University of Liege. The seismic signals were chosen in the European Strong-motion database (Ambraseys et al., 2002) according the following criteria: a bedrock station (to avoid site effect), a strike-slip fault mechanism and a distance between the station and the epicenter around 20-30 km. The aqueduct is located at about 25 km of the Dead Sea Fault. We tested several magnitudes for the purpose of estimate the magnitude of the earthquake(s) which destroy(s) the studied aqueduct. Our results highlight the bond between the magnitude, the damage and the weakness area of this type of structure. [less ▲]

Detailed reference viewed: 55 (6 ULg)
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See detailThe Amik Lake in Southern Turkey over the last 4000 years, a new paleoseismological record of ruptures along the Northern Dead Sea Fault
Hubert, Aurelia ULg; El Ouahabi, Meriam ULg; Lebeau, Hèlène et al

Poster (2014, June 30)

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle ... [more ▼]

The study focuses on the sedimentary record of the Amik Lake occupying the central part of a pull-apart basin. The Basin is crossed by The Dead Sea Fault (DSF), a major neotectonic structure in the Middle East extending from the Red Sea in the south to the East Anatolian Fault Zone in the north. Around the Amik Basin, continuous human occupation is attested since 6000-7000 BC. Indeed the low-lying Amuq plain is covered by tell settlements first explored by Robert Braidwood in the 1930s. Our objective in this presentation is to look at major paleo-environmental changes recorded in the Amik Lake over the last 4000 years and in particular its potential paleoseimic sedimentary record. The lake has been drained and progressively dried up since the mid-50s so that it is not watered during the summer season and constitutes a unique opportunity to collect sediment records. Sediments were collected at 1 cm to 2 cm intervals in a trench and in cores up to a depth of 5 meters in the clay deposits. A diverse array of complementary methods is applied to study the records: magnetic susceptibility, grain size, organic matter and inorganic carbon (L.O.I), XRD mineralogy, XRF geochemistry, carbon geochemistry and clay mineralogy. The age of the record is constrained combining radionuclide and radiocarbon dating. The sedimentary record shows large earthquake related structural disturbances and smaller siliciclastic sedimentary events. The siliciclastic input would be related to enhanced detritical sedimentation related to earthquake shaking. The latter is further investigated looking at intensities and shake maps related to the last 19th century M>7 earthquakes in the area and landslide prone area in the lake catchment. [less ▲]

Detailed reference viewed: 49 (6 ULg)
See detailReview of the Newmark method predicting seismic slope displacements - the focus on the Arias Intensity amplification factor
Torgoev, Almazbek ULg; Havenith, Hans-Balder ULg; Lamair, Laura ULg

in Proceedings of the International Symposium in Commemoration of the 2008 Wenchuan Earthquake (2013, May)

Detailed reference viewed: 14 (1 ULg)
See detailParametric numerical study of seismic slope stability and the Newmark method
Havenith, Hans-Balder ULg; Torgoev, Almazbek ULg; Lamair, Laura ULg

Conference (2013, April)

2D dynamic modelling of seismic slope stability is applied to a landslide-prone area in Central Asia, the Mailuu-Suu Valley, situated in the south of Kyrgyzstan. The calculations are made with models ... [more ▼]

2D dynamic modelling of seismic slope stability is applied to a landslide-prone area in Central Asia, the Mailuu-Suu Valley, situated in the south of Kyrgyzstan. The calculations are made with models constructed from over 30 profiles located in the target area, presenting different geological, tectonic and morphological settings. One part of the profiles were selected within landslide zones, the other part was selected in stable areas. Many of the landslides are complex slope failures involving falls, rotational sliding and/or planar sliding and flows. These input data were extracted from a 3D structural geological model built with the GOCAD software. Geophysical and geomechanical parameters were defined on the basis of results obtained by multiple surveys performed in the area over the past 15 years. These include geophysical investigation, seismological experiments and ambient noise measurements. Dynamic modelling of slope stability is performed with the UDEC version 4.01 software that is able to compute deformation of discrete elements. Inside these elements both elasto-plastic and purely elastic materials (similar to rigid blocks) were tested. Various parameter variations were tested to assess their influence on the final outputs. For a few models groundwater flow is included. The total parametric study involved more than 100 different models (about 800 computation hours). Preliminary results allow us to compare Newmark displacements computed using different GIS approaches (Jibson et al., 1998; Miles and Ho, 1999, among others) with the displacements computed using the original Newmark method (Newmark, 1965, here simulated seismograms were used) and displacements produced along joints by the corresponding 2D dynamical models. The generation of seismic amplification and its impact on peak-ground-acceleration, Arias Intensity and permanent slope movements (total and slip on joints) is assessed for numerous morphological-lithological settings (curvature, slope angle, surficial geology, various layer dips and orientations) throughout the target area. The final results of our studies should allow us to define the limitations of the simplified GIS-based Newmark displacement modelling; thus, the verified method would make landslide susceptibility and hazard mapping in seismically active regions more reliable. [less ▲]

Detailed reference viewed: 38 (5 ULg)
Peer Reviewed
See detailA Review of Recent Case Studies of Landslides Investigated in the Tien Shan Using Microseismic and Other Geophysical Methods
Torgoev, Almazbek ULg; Lamair, Laura ULg; Torgoev et al

in Ugai, K; Wakai, A; Yagi, H (Eds.) Proceedings of the International Symposium on Earthquake-induced landslides (2012, December)

This paper reviews recent case studies completed on landslides (and dams) with probable (post-) seismic origin or susceptible to seismic failure in the Tien Shan, Central Asia. The first investigation ... [more ▼]

This paper reviews recent case studies completed on landslides (and dams) with probable (post-) seismic origin or susceptible to seismic failure in the Tien Shan, Central Asia. The first investigation presented here was carried out in 2005 on the Kainama earthflow, mainly composed of loess, which occurred in April 2004 and killed 33 people. Geophysical and seismological were used to build a reliable 3D model of the geometry and properties of the subsurface layers. The paper will also present results from microseismic measurements on loess landslides in Tajikistan that partly have a seismic origin. They are located close to the area that was affected in 1949 by the M=7.4 Khait earthquake and the numerous landslides triggered during the event, including the Khait rock avalanche. [less ▲]

Detailed reference viewed: 54 (9 ULg)
See detailCalcul de l’aléa sismique pour une région dans le Tien-Shan Central, étude in situ et modélisation numérique dynamique de la réponse sismique de sites de bassin de retenue.
Lamair, Laura ULg

Master's dissertation (2012)

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is ... [more ▼]

Kyrgyzstan is situated in the heart of the Tien Shan. During the last two centuries, several M>7 earthquakes occurred in this country. Therefore, a good knowledge of seismic hazard in this area is essential, not only at regional scale but also at local scale. First, this work presents a detailed analysis of seismic hazard in the Central Tien Shan. Several seismic hazard map have been made but none of them include paleoseismic data. Our maps are based on previous studies of probabilistic seismic hazard of the Kyrgyz Tien Shan (Abdrakhmatov et al., 2003). We integrate in our calculation the palaeoseismicity of the Talas Fergana Fault. It allows us to take into consideration strong earthquakes with high return periods. The final results are presented as maps with different return periods (100, 200, 475, 1000, 2000, 5000 and 10000 years). The outcomes are discussed in comparison with previous results, with GSHAP predictions (Ulomov et al., 1999) and with probabilistic seismic hazard map (Abdrakhmatov et al., 2003). The purpose of the second part of this study is the assessment of local seismic hazard of Tuyuk-Suu and Taldy-Bulak "D" tailings, both located in the Minkush valley. First, seismic wave amplifications are determined by means of spectral ratios of the horizontalto- vertical (H/V) components acquired through ambient noise measurements. Secondly, a dynamic modeling of the two tailings is performed. It is based on peak ground acceleration calculated previously for a return period of 1000 years. The dynamic modeling gives Fourier spectra for several histories. Spectral ratios obtained from dynamic modeling are compared with H/V measurement in order to estimate site effects. [less ▲]

Detailed reference viewed: 48 (12 ULg)
See detailDetailed Seismic Hazard Assessment for The Central Tien Shan, Kyrgyzstan
Lamair, Laura ULg; Havenith, Hans-Balder ULg; Abdrakhmatov, K

Poster (2012, August 23)

Detailed reference viewed: 24 (3 ULg)