Éditeur(s) : Chez Couturier Chez Couturier ( Paris )
Résumé : "Appové, ce 5 octobre 1770"--P. 4.
Haiti
Haïti
Haiti
Haïti
Haiti

819751677
ocn819751677
http://ufdc.ufl.edu/AA00021792/00001

Éditeur(s) : HAL CCSD Seismological Society of America
Résumé : International audience
Abstract The continuous record of large surface-rupturing earthquakes along the Dead Sea fault brings unprecedented insights for paleoseismic and archaeoseismic research. In most recent studies, paleoseismic trenching documents the late Holocene faulting activity, while tectonic geomorphology addresses the long-term behavior (>10 ka), with a tendency to smooth the effect of individual earthquake rupture events (Mw >7). Here, we combine historical, archaeological, and paleoseismic investigations to build a consolidated catalog of destructive surface-rupturing earthquakes for the last 14 ka along the left-lateral Jordan Valley fault segment. The 120- km-long fault segment limited to the north and the south by major pull-apart basins (the Hula and the Dead Sea, respectively) is mapped in detail and shows five subsegments with narrow stepovers (width < 3 km). We conducted quantitative geomorphology along the fault, measured more than 20 offset drainages, excavated four trenches at two sites, and investigated archaeological sites with seismic damage in the Jordan Valley. Our results in paleoseismic trenching with 28 radiocarbon datings and the archaeoseismology at Tell Saydiyeh, supplemented with a rich historical seismic record, document 12 surface-rupturing events along the fault segment with a mean interval of ∼1160 yr and an average 5 mm=yr slip rate for the last 25 ka. The most complete part of the catalog indicates recurrence intervals that vary from 280 yr to 1500 yr, with a median value of 790 yr, and suggests an episodic behavior for the Jordan Valley fault. Our study allows a better constraint of the seismic cycle and related short-term variations (late Holocene) versus long-term behavior (Holocene and late Pleistocene) of a major continental transform fault.
ISSN: 0037-1106

hal-00747401
https://hal.archives-ouvertes.fr/hal-00747401
DOI : 10.1785/0120100097

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We recover the Holocene earthquake history of seven seismogenic normal faults in the Fucino system, central Italy. We collected 800 samples from the well-preserved limestone scarps of the faults and modeled their 36Cl concentrations to derive their seismic exhumation history. We found that > 30 large earthquakes broke the faults in synchrony over the last 12 ka. The seven faults released strain at the same periods of time, 12-9 ka, 5-3 ka, and 1.5-1 ka. On all faults, the strain accumulation and release occurred in 3-6 ka supercycles, each included a 3-5 ka phase of slow (≤ 0.5-2 mm/yr) strain accumulation in relative quiescence, followed by a cluster of three to four large earthquakes or earthquake sequences that released most of the strain in < 1-2 ka. The large earthquakes repeated every 0.5 ± 0.3 ka during the paroxysmal phases and every 4.3 ± 0.9 ka between those phases. Earthquakes on the northern faults produced twice larger surface slips (~ 2 m) and had larger magnitudes (Mw 6.2-6.7) than those on the southern faults. On most faults, the relative strain level was found to control the amount of slip and the time of occurrence of the next large earthquake. Faults entered a phase of clustered activity once they had reached a specific relative strain threshold. The Tre Monti fault is identified as the most prone to break over the next century. Our data document earthquake synchrony and clustering at a broader space and time scale than has been reported to date.
ISSN: 0148-0227

hal-00903460
https://hal.archives-ouvertes.fr/hal-00903460
DOI : 10.1002/jgrb.50299

Éditeur(s) : HAL CCSD Seismological Society of America
Résumé : With the assistance of the ASTER team (M. Arnold, G. Aumaître, D. Bourlès, and K. Keddadouche)
International audience
The Bulnay earthquake of 23 July 1905 (Mw 8.3–8.5), in north‐central Mongolia, is one of the world’s largest recorded intracontinental earthquakes and one of four great earthquakes that occurred in the region during the twentieth century. The 375 km long surface rupture of the left‐lateral, strike‐slip, N095°E‐trending Bulnay fault associated with this earthquake is remarkable for its pronounced expression across the landscape and for the size of features produced by previous earthquakes. Our field observations suggest that in many areas the width and geometry of the rupture zone is the result of repeated earthquakes; however, in those areas where it is possible to determine that the geomorphic features are the result of the 1905 surface rupture alone, the size of the features produced by this single earthquake are singular in comparison to most other historical strike‐slip surface ruptures worldwide. Along the 80 km stretch, between 97.18° E and 98.33° E, the fault zone is characterized by several meters width and the mean left‐lateral 1905 offset is 8.9±0.6  m with two measured cumulative offsets that are twice the 1905 slip. These observations suggest that the displacement produced during the penultimate event was similar to the 1905 slip. Morphotectonic analyses carried out at three sites along the eastern part of the Bulnay fault allow us to estimate a mean horizontal slip rate of 3.1±1.7  mm/yr over the Late Pleistocene–Holocene period. In parallel, paleoseismological investigations show evidence for two earthquakes prior to the 1905 event, with recurrence intervals of ∼2700–4000  yrs.
ISSN: 0037-1106

hal-01179837
https://hal.archives-ouvertes.fr/hal-01179837
https://hal.archives-ouvertes.fr/hal-01179837v2/document
https://hal.archives-ouvertes.fr/hal-01179837/file/rizza2015.pdf
DOI : 10.1785/0120140119

Éditeur(s) : HAL CCSD University of Arizona
Résumé : International audience
Taiwan is a young and seismically active mountain belt, where a series of strong earthquakes (M>7) have occurred over the past hundred years. Identifying historical earthquakes around Taiwan is a key to better constrain the geodynamic of this active region. Sedimentological and geochemical analyses of surface sediments from one station offshore east Taiwan revealed the presence of coarse-grained layers interpreted as turbidites. The age of these layers have been determined by 210Pb, 137Cs, and 241Am chronology. Dating of the three most recent turbidites provides ages of AD 2001±3, AD 1950±5, and AD 1928±10. The results show striking temporal correspondence of turbidite layers to large (M≥6.8) earthquakes recorded in the region since the 20th century. The chronologies of sediment layers lead us to believe that turbidites resulted from the 2003 Taitung earthquake (M 6.8), the 1951 Chengkong earthquake (M 7.1), and the 1935 Lutao earthquake (M 7.0), respectively. Such a good correlation between turbidites and high-magnitude (M≥6.8) historical and instrumental seismic events suggests that turbidite paleoseismology constitutes a valuable tool for earthquake assessment in the eastern Taiwan margin. Moreover, the modern reservoir radiocarbon age and the regional marine reservoir correction (ΔR) of the Kuroshio Current off Taiwan were estimated by comparing accelerator mass spectrometry (AMS) 14C ages with ages derived from corrected 210Pb profiles and historical accounts of identifiable seismic events. Such a determination is important to calibrate the 14C ages of marine materials for accurate comparison of marine and continental geological records. Our calculated mean ΔR value of 232±54 14C yr (n=2) is higher than its modern value of 86±40 14C yr. This high value can be explained by the presence of local upwelling cells and turbulence in the Kuroshio Current, north of Green Island. These upwelling cells bring 14C-depleted water to the surface, resulting in an increase of the modern ΔR value in this portion of the Kuroshio Current.
ISSN: 0033-8222

hal-01306986
https://hal.archives-ouvertes.fr/hal-01306986
DOI : 10.1017/RDC.2015.3

Éditeur(s) : Amer Geophysical Union
Résumé : The oblique convergence between North American and Caribbean plates is accommodated in a bookshelf faulting manner by active, oblique-normal faults in the northern part of the Lesser Antilles arc. In the last 20 years, two M > 6 earthquakes occurred along a large, arc parallel, en echelon fault system, the 16 March 1985 in Redonda and 21 November 2004 in Les Saintes. A better understanding of active faulting in this region permit us to review the location and magnitude of historical earthquakes by using a regional seismic attenuation law. Several others moderate earthquakes may have occurred along the en echelon fault system implying a strong seismic hazard along the arc. These faults control the effusion of volcanic products and some earthquakes seem to be correlated in time with volcanic unrest. Shallow earthquakes on intraplate faults induced normal stress and pressure changes around neighboring volcano and may have triggered volcanic activity. The Redonda earthquake could have initiated the 1995 eruption of Montserrat's Soufriere Hills by compressing its plumbing system. Conversely, pressure changes under the volcano increased Coulomb stress changes and brought some faults closer to failure, promoting seismicity. We also discuss the magnitude of the largest 11 January 1839 and 8 February 1843 megathrust interplate earthquakes. We calculate that they have increased the stress on some overriding intraplate faults and the extensional strain beneath several volcanoes. This may explain an increase of volcanic and seismic activity in the second half of the 19th century culminating with the devastating, 1902 Mount Pelee eruption.
Journal Of Geophysical Research-solid Earth (0148-0227) (Amer Geophysical Union), 2011-10 , Vol. 116 , N. B10308 , P. 1-26

Droits : Copyright 2011 by the American Geophysical Union
http://archimer.ifremer.fr/doc/00200/31097/29515.pdf
DOI:10.1029/2011JB008443
http://archimer.ifremer.fr/doc/00200/31097/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The ∼55 km-long Firouzkuh fault is located in the Central Alborz Mountains of Iran. It is a left-lateral fault, which dips to the south, and possesses a small dip-slip component of motion that we interpret to result from extension. The ratio of horizontal to vertical displacement across the fault, calculated from the cumulative displacement of landscape features, is 7.6. We provide constraints on the timing of the last earthquake on the Firouzkuh fault from two trenches (T1 and T2) across the fault zone, excavated in 2004, and located east of Firouzkuh city. The trenches expose faulted sedimentary deposits. Two optically-stimulated luminescence (OSL) ages from sediments in the lower part of trench T1 date from the late Pleistocene (15.9 ± 0.9 ka and 27.1 ± 1.7 ka). The younger of the two dated units in T1 is displaced vertically across the fault by 2.2–4.4 m, from which we estimate a strike-slip displacement of 18.2–33.4 m, and hence a average horizontal slip-rate of 1.1–2.2 mm/yr. The sediments exposed in T1 do not yield constraints on the most recent earthquake history. In trench T2, however, human skeletal remains of a middle aged male, which yield a radiocarbon age of 1159 ± 28 BP (corresponding to a mean calendar age of 791 AD), were found within a faulted alluvial layer at a depth of 60–70 cm from the surface. The existence of these medieval human places shows that a surface-rupturing earthquake occurred at some time after 1159 ± 28 BP. The amount of slip in each earthquake on the Firouzkuh fault is difficult to estimate, but assuming the entire ∼55 km fault length ruptures in each event, they will have had a maximum magnitude of 7.1. At our estimated late Quaternary slip-rate of ∼1.1–2.2 mm/yr magnitude 7.1 earthquakes, involving ∼1.2 m average displacement, would be expected to occur every ∼1100–540 years. As the last earthquake on the Firouzkuh fault may be up to ∼700 years in age we suggest that the Firouzkuh fault is a major hazard for earthquakes in the near future.
ISSN: 0743-9547

hal-01122835
https://hal.archives-ouvertes.fr/hal-01122835
DOI : 10.1016/j.jseaes.2013.12.018

Éditeur(s) : Leslie's Weekly Leslie's Weekly ( [New York] )
Résumé : Credit: Historical Museum of Southern Florida, 2007-205-2.
Digital image 2007
Kingston (Jamaica)

Droits : All rights reserved by the source institution.
2007-205-2

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Large earthquakes nucleate at tectonic plate boundaries, and their occurrence within a plate's interior remains rare and poorly documented, especially offshore. The two large earthquakes that struck the northeastern Indian Ocean on 11 April 2012 are an exception: they are the largest strike-slip events reported in historical times1, 2 and triggered large aftershocks worldwide3. Yet they occurred within an intra-oceanic setting along the fossil fabric of the extinct Wharton basin, rather than on a discrete plate boundary4, 5, 6, 7, 8. Here we show that the 11 April 2012 twin earthquakes are part of a continuing boost of the intraplate deformation between India and Australia that followed the Aceh 2004 and Nias 2005 megathrust earthquakes, subsequent to a stress transfer process recognized at other subduction zones9, 10. Using Coulomb stress change calculations, we show that the coseismic slips of the Aceh and Nias earthquakes can promote oceanic left-lateral strike-slip earthquakes on pre-existing meridian-aligned fault planes. We further show that persistent viscous relaxation in the asthenospheric mantle several years after the Aceh megathrust explains the time lag between the 2004 megathrust and the 2012 intraplate events. On a short timescale, the 2012 events provide new evidence for the interplay between megathrusts at the subduction interface and intraplate deformation offshore. On a longer geological timescale, the Australian plate, driven by slab-pull forces at the Sunda trench, is detaching from the Indian plate, which is subjected to resisting forces at the Himalayan front6, 8, 11.
ISSN: 0028-0836

hal-00767569
https://hal.archives-ouvertes.fr/hal-00767569
DOI : 10.1038/nature11520

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
In this paper, we present the first estimate of the Holocene deformation along the southern front of Gibraltar arc (Morocco) and the first field constraints on the local 1755 CE Fes-Meknes surface rupturing earthquake which could be associated to the “Great Lisbon Earthquake” (M > 8.5) in November 1st, 1755. Using satellite imagery, aerial photographs and field investigations, we carried out a morphotectonic study along the ~ 150 km-long Southern Rif Front (SRF) to identify the most recent evidences of tectonic activity. Analyzed offset alluvial deposits confirm that (i) the last ~ 5 ka cumulative deformation leading to a slip rate of ~ 3.5 ± 1 mm/yr for this segment of the SRF is consistent with the GPS derived horizontal shortening rate of 2–4 mm/yr and (ii) a recent major earthquake ruptured a ~ 30 km-long segment along the SRF. Based on deposits dating and historical seismicity we propose that this seismic event occurred in 1755 as a local earthquake. Even though this 1755 local event cannot be considered as a strong aftershock of the main Lisbon seismic event (M > 8.5), their temporal closeness, their occurrence under the same convergent stress regime (~ NNW-SSE-oriented compression) and the fact that Fes-Meknes area was strongly shaken during the Lisbon earthquake, raises the question of the possible triggering of the Fes earthquake. Anyway, our new results suggest that most of the Nubia-Rif belt convergence is accommodated by the SRF, making it potentially the most destructive structure of the Rif.
ISSN: 0040-1951

hal-01622048
https://hal.archives-ouvertes.fr/hal-01622048
DOI : 10.1016/j.tecto.2017.05.036

Éditeur(s) : HAL CCSD
Résumé : International audience
Despite the recent interest in psychiatric illness in prison, the psychopathology of the Remire-Montjoly prison population remains largely unknown. Subject to significant population movements, French Guiana and its prison houses a very mixed population in which recent history has left a strong mark (earthquake in Haïti, civil war in Suriname, violence related to gold mining population and drug trafficking). These negative life events appear as potential vectors of psychological trauma. Additionally, strong links have been established in the literature between post-traumatic stress disorder (PTSD) and many other psychiatric disorders, including suicidal behavior and addictions. Under these conditions, we felt it essential to focus on the identification of PTSD in this sensitive population.Through adapted reception interviews, we tried to identify the PTSD, to describe by means of socio-demographic factors the studied population and to detect psychiatric comorbidities. The screening tool was the M.I.N.I. 5.0, which identifies 17 psychiatric disorders including the PTSD, based on the DSM IV definition. The target population was the prison incomers, agreeing to participate in the study, aged more than 18 years old and imprisoned between 18 January 2013 and 31 December 2013. To this date, 549 inmates were included in the study.The main result of this study was a prevalence of PTSD of 17% for incomers in detention. We found that the PTSD+ population is more likely to be female (15% against 7% p = 0.0246), which is consistent with the literature data. The M.I.N.I. 5.0 showed a higher prevalence of psychiatric disorders in the PTSD+ group. This association was confirmed in several types of pathology like mood disorders including: major depressive episode and manic or hypomanic episode, suicidal risk, some anxiety disorders including: panic disorder, obsessive-compulsive disorder and generalized anxiety disorder. Strong association was found for current major depressive episode, current manic or hypomanic episode and suicidal risk (p < 0.005).The prevalence of PTSD is very high in this study, about 24 times higher than in a general population survey using the same screening tool.A large number of comorbidities have been identified, which corresponds to those described in the literature. The specific issues of psychiatry in prison lead us to examine more specifically the significance of the results about suicide risk. A comprehensive suicide risk (sum of medium and high risk screened by the M.I.N.I.) was found in significantly more PTSD+ inmates (17% versus 7%, p = 0.005). This study supports the need for routine screening of PTSD among incomers in detention. This disease is both worrying and common in this population but the real issues are the comorbidities. Suicidal potential is among the most important issues in detention. Its evaluation should be completed by an early recognition of a PTSD.
Soumis à des mouvements de population importants, la Guyane Française et son centre pénitentiaire abritentune population métissée chez qui l’histoire récente a laissé une empreinte forte (tremblement de terre en Haïti,guerre civile au Suriname, violence liée à l’orpaillage et au trafic de stupéfiants). Ces événements de vienégatifs apparaissent comme autant de vecteurs potentiels de psychotraumatismes. Dans ces conditions, il nous a paru essentiel de mettre l’accent sur le repérage du TSPT (Trouble de Stress Post-traumatique) dans cette population sensible. A l'aide d’entretiens d’accueil dédiés nous nous sommes proposé de repérer les TSPT, de décrire sur un plan sociodémographique la population étudiée et de rechercher les comorbidités psychiatriques. Le résultat principal de cette étude était une prévalence du TSPT de 17% chez les arrivants en détention. Le MINI 5.0 a montré une prévalence plus élevée des pathologies psychiatriques dans le groupe présentant un TSPT avec un lien très fort (p<0.005) pour l’épisode dépressif majeur actuel, l’épisode (hypo)maniaque actuel et le risque suicidaire. Cette étude appuie la nécessité d’avoir un dépistage systématique du TSPT chez les arrivants en détention. Cette pathologie est à la fois fréquente dans cette population et invalidante mais ce sont ses comorbidités, dont le potentiel suicidaire, qui font tout l’enjeu d’un repérage précoce.
ISSN: 0383-6320

inserm-01421075
http://www.hal.inserm.fr/inserm-01421075
http://www.hal.inserm.fr/inserm-01421075/document
http://www.hal.inserm.fr/inserm-01421075/file/2016%2C%20Arnal%20-%20Post-Traumatic%20Stress%20Disorder%20among%20Incomers%20in%20Remire-Montjoly%20Prison%2C%20French%20Guiana.pdf
PUBMED : 27570960

Éditeur(s) : HAL CCSD
Résumé : The purpose of this work is to specify the deformation offshore East of Taiwan by characterizing major active faults in particular at the level of the Ryukyu forearc. The major problem associated with the study of this region is that earthquakes are located outside the permanent networks. Consequently, this led to some unprecise earthquake locations limiting tectonic and statistical analyses, and therefore the correct estimation of the seismic hazard. This work is included in the project ANR ACTS (Active Tectonics and Seismic Hazard in Taiwan). To achieve this goal, we worked on three different timescales for which a different localization method has been proposed to obtain a clear image of seismic deformation and highlight major faults offhore East of Taiwan. First, at the scale of the century (from the analysis of a seismicity catalogue with homogeneous magnitude), the instrumental historical earthquakes (1897-2007) show that the Ryukyu margin was affected by 6 earthquakes of magnitude greater than 7 with 4 of them for which the responsible fault is unknown. We propose a method of relative location to relocate the historic events from the time difference of P and S arrival times (Ts-Tp) at each station. The location is obtained by searching for "analogue" earthquakes in the recent instrumental catalogue (1991-2008) for which Ts-Tp at each station is close. This method has been applied to the largest (in terms of magnitude) earthquake ever recorded in Taiwan, the earthquake of June 5, 1920 (M7.7 +/- 0.2). A rupture along the interplate of the Ryukyu subduction with a possible nucleation at the downdip limit of a splay-fault is certainly responsible of this earthquake. Then, at the scale of the decade, the improvement of the method of absolute location based on MAXimum of Intersection of EDT (MAXI, EDT: Equal Differential Time) allows to better extract the erroneous arrival times and prevents the "trade-off" between depth and origin time, and between depth and epicentral position when the azimuthal coverage is low (gap Azimuthal > 180degre). Synthetic tests show the effectiveness of MAXI (using P-wave only) to determine the parameters x, y and z even when the azimuthal gap is important. In the latter case, the quality of the results is dependent on the velocity model to represent the 3D structure of the Earth. We propose an approach involving the use of a 3D a priori P-wave velocity model to locate earthquakes which are lateral and remote to the seismic network. An application to the case of Taiwan and Ecuador validates this approach. Finally, at the level of a few months, the marine geophysical campaign RATS (Ryukyu Arc: Tectonics and Seismology) was conducted in two stages. A passive seismology experiment from July to October, 2008 (RATS1) has been conducted over the forearc of the Ryukyus and then active seismic experiment (refraction and reflection) was conducted in May 2009 in a NNE - SSW line through the Ryukyu margin. These two combined experiments allow improving our knowledge about the crustal structure of the margin. At the level of the forearc, the basement of the forearc is characterized by vertical backstop and a very deformed basis certainly associated with a significant out of sequence deformation. In depth, the downgoing plate is certainly affected by a tear that controls the seismicity in the region of transition between the subduction and collision.
Le but de ce travail est de préciser la déformation en mer à l'est de Taïwan et de notamment caractériser les failles actives majeures en particulier au niveau de l'avant-arc des Ryukyus. Le problème majeur associé à l'étude de cette région est que les séismes sont localisés en dehors des réseaux permanents et que cela conduit à des localisations peu précises limitant les analyses statistiques, tectoniques et donc l'estimation correcte de l'aléa sismique. Ce travail est inclus dans le projet ANR ACTS (Active Tectonics and Seismic Hazard in Taiwan). Pour atteindre cet objectif, nous travaillons à trois échelles de temps différentes pour lesquelles une méthode de localisation différente a été proposée pour obtenir une image précise de la déformation sismique et mettre en évidence les failles majeures en mer à l'est de Taïwan. D'abord, à l'échelle du siècle (à partir de l'analyse d'un catalogue de sismicité homogène en magnitude), les séismes historiques instrumentaux (1897-2007) montrent que la marge des Ryukyus a été affectée par 6 séismes de magnitude supérieure à 7 dont 4 pour lesquels la faille responsable n'est pas connue. Nous proposons une méthode de localisation relative qui permet de relocaliser les évènements historiques à partir des différences de temps d'arrivées P et S (Ts-Tp) à chaque station. La localisation est obtenue en recherchant les séismes analogues dans le catalogue instrumental récent (1991-2008) pour lesquels Ts-Tp à chaque station est proche. Cette méthode a été appliquée au plus gros séisme (en terme de magnitude) jamais enregistré à Taïwan, le séisme du 5 juin 1920 (M7.7 $pm$ 0.2). Ce séisme a certainement pour origine une rupture sur l'interplaque sismogène de la subduction des Ryukyus avec une possible nucléation à la base d'une faille hors-séquence. Ensuite, à l'échelle de la dizaine d'années, l'amélioration de la méthode de localisation absolue du MAXimum d'Intersection EDT (MAXI, EDT: Equal Differential Time) permet de mieux extraire les temps d'arrivées erronés et empêche les "trade-off" entre profondeur et temps d'origine et, entre profondeur et position épicentrale lorsque la couverture azimutale est faible (gap azimutal > 180°). Des tests synthétiques montrent l'efficacité de MAXI (en utilisant les ondes P uniquement) à déterminer les paramètres x, y et z même lorsque le gap azimutal est important. Dans ce dernier cas, la qualité des résultats reste dépendant du modèle de vitesse à représenter la structure 3D de la Terre. Nous proposons une démarche associant l'utilisation d'un modèle de vitesse des ondes P 3D a priori avec la méthode MAXI pour localiser les séismes qui sont latéraux et éloignés du réseau. Une application au cas de Taïwan et en Équateur valide cette approche. Enfin, à l'échelle de quelques mois, la campagne de géophysique marine RATS (Ryukyu Arc: Tectonics and Seismology) a été menée en deux temps. Une expérience de sismologie passive de juillet à octobre 2008 (RATS1) a été menée au-dessus de l'avant-arc des Ryukyus puis une expérience de sismique active (réfraction et réflexion) a été menée en mai 2009 sur une ligne NNE-SSW à travers la marge des Ryukyus. Ces deux expériences combinées permettent d'améliorer notre connaissance de la structure crustale de la marge. Au niveau de l'avant-arc, le socle de l'avant-arc est caractérisé par une extrémité formant un butoir vertical et une base très déformée certainement associée à une importante déformation hors-séquence. En profondeur, la plaque plongeante est certainement affectée par une déchirure qui contrôle la sismicité dans cette région de transition entre la subduction et la collision.
https://tel.archives-ouvertes.fr/tel-00660737

tel-00660737
https://tel.archives-ouvertes.fr/tel-00660737
https://tel.archives-ouvertes.fr/tel-00660737/document
https://tel.archives-ouvertes.fr/tel-00660737/file/Thesis_small.pdf

Éditeur(s) : HAL CCSD
Résumé : Taiwan is a young mountain belt, known as one of the most active area in the world. Since the beginning of the 20th century more than twenty _ Mw 7 earthquakes have struck the island. However, the occurrence of larger events (_Mw 8) is still a matter of debate. In this framework it is of key importance to obtain longer record in order to evaluate the occurrence of large past earthquakes. The sub-aqueous paleoseismology, based on the record of the sedimentary gravity deposits, appears as a serious alternative to approach this thematic and is a rapidly advancing field that has the potential to illuminate the long-term history of seismicity.The first part of this work was to investigate the present sedimentary systems off east Taiwan, essential to understand the morphosedimentary features, sedimentary facies and processes governing the evolution of the submarine slope, and the controlling factors of the recent sedimentation. Our results showed that the offshore slope east Taiwan is affected by a variety of sedimentary systems and processes, and that turbidity currents appear as the main erosional processes covering nearly 60% of the sedimentary record. Turbidity currents are generated by distinct controlling factors such as tectonic and climatic activity that enabled us to define twoend-members relative to turbidity currents initiation: Turbidity currents preconditioned by tectonic activity and triggered by earthquakes shaking and likely deposited into intra-slope basin and turbidity currents driven by climatic activity such as extreme floods or typhoons, generated in basin directly connected with onland rivers.The second part consisted to apply a paleoseismic approach, based on turbidites record, at two time-scales. First, we tested and validated the method by correlating turbidites deposits with instrumental earthquakes. Then, once calibrated we extended the time-series back in time. We dated the three most recent turbidites layers circa 2001 ± 3 AD, 1950 ± 5 AD and 1928 ± 10 AD. Using empirical relationship that link peakground acceleration, distance and magnitude to calibrate the seismic sources, we correlate these three turbidites with instrumental earthquakes: the Chengkong Earthquake 12/10/2003 (Mw 6.8), the 11/24/1951 Taitung Earthquake (Mw 7.1) and the 9/4/1935 Lutao Earthquake (Mw 7.0) respectively. Applying criteria to discriminating the different triggering mechanisms for turbidity current generation, we propose that earthquakes are the main triggering mechanisms. Dating and age modeling provided a part of the chronology of extreme events since the last 3000 years and allowed us to estimate return time for earthquakes Mw _ 6.8.This work represents a good starting-point for future investigations in order to better assess Holocene time series of extreme events.
La chaine de Taïwan représente l’une des zones les plus actives au monde. Depuis le début du XXe siècle, plus d’une vingtaine de séismes _Mw 7 ont affecté l’île. Cependant la probabilité d’occurrence de séismes plus importants (_Mw 8) est toujours matière à débat. Dans un tel contexte, il apparait donc important d’obtenir des enregistrements plus anciens pour évaluer l’occurrence de tels évènements. La paléosismologie marine, basée sur l’enregistrement des dépôts issus de la sédimentation gravitaire, apparait comme une alternative sérieuse afin d’illuminer l’histoire de la sismicité sur des périodes anciennes. Ce travail de thèse apporte de nouvelles contraintes sur l’histoire sismique au large, à l’est de Taïwan, au cours des derniers 3000 ans.La première partie de ce travail consiste à caractériser les systèmes sédimentaires récents. Cette étape fut essentielle pour la compréhension des processus, faciès sédimentaires et les facteurs de contrôle de la sédimentation qui régissent l’évolution de la pente sous-marine. Ces résultats ont montré que l’Est de Taïwan est caractérisé par une grande variabilité de processus et que les courants de turbidité dominent l’enregistrement sédimentaire.Les courants de turbidité sont générés par deux facteurs distincts : l’activité tectonique/sismique et l’activité climatique. La deuxième partie de ce travail est consacrée à l’approche paléosismique en utilisant les dépôts de turbidités comme marqueurs des paléoséismes. Pour ce faire, nous avons dans un premier temps testé et validé l’approche à l’échelle du siècle dernier. Ensuite une fois calibré, nous avons pu étendre les séries temporelles à l’échelle de l’Holocène. Nous avons daté les trois plus récents évènements turbiditiques autour de 2001 ± 3 AD, 1950 ± 5 AD et 1928 ± 10 AD. En utilisant des relations empiriques intégrant magnitude, distance et valeur du "peak ground acceleration", nous avons pu calibrer la source sismique et ainsi corréler ces trois turbidites à trois séismes instrumentaux : le séisme de Chengkong (12/10/2003) (Mw 6.8), le séisme de Taitung (11/24/1951) (Mw 7.1) et le séisme de Lutao (9/4/1935) (Mw 7.0). Au-delà du siècle dernier, les datations et modèles d’âges nous permettent d’établir une partie de la chronologie des évènements extrêmes sur une période de 3000 ans et d’estimer un temps de retour pour des évènements de l’ordre _Mw 7. Les résultats ont toutefois montré que ces temps de retour sont nettement supérieurs à ceux connus sur le siècle dernier, ce qui suggère que tous les séismes ne sont pas enregistrés par les dépôts sédimentaires marins. Ce travail de thèse a donc permis de montrer que les dépôts issus de la sédimentation évènementielle peuvent être considérés comme marqueurs de la sismicité et que cette approche peut constituer un outil complémentaire pour les études portant sur le risque sismique.
https://tel.archives-ouvertes.fr/tel-01661529

NNT : 2014MON20133
tel-01661529
https://tel.archives-ouvertes.fr/tel-01661529
https://tel.archives-ouvertes.fr/tel-01661529/document
https://tel.archives-ouvertes.fr/tel-01661529/file/55796_LEHU_2014_archivage_cor.pdf

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : We present a preliminary probabilistic tsunami hazard assessment of Canadian coastlines from local and far-field, earthquake, and large submarine landslide sources. Analyses involve published historical, palaeotsunami and palaeoseismic data, modelling, and empirical relations between fault area, earthquake magnitude, and tsunami run-up. The cumulative estimated tsunami hazard for potentially damaging run-up (≥1.5 m) of the outer Pacific coastline is ~40-80 % in 50 years, respectively one and two orders of magnitude greater than the outer Atlantic (~1-15 %) and the Arctic (<1 %). For larger run-up with significant damage potential (≥3 m), Pacific hazard is ~10-30 % in 50 years, again much larger than both the Atlantic (~1-5 %) and Arctic (<1 %). For outer Pacific coastlines, the ≥1.5 m run-up hazard is dominated by far-field subduction zones, but the probability of run-up ≥3 m is highest for local megathrust sources, particularly the Cascadia subduction zone; thrust sources further north are also significant, as illustrated by the 2012 Haida Gwaii event. For Juan de Fuca and Georgia Straits, the Cascadia megathrust dominates the hazard at both levels. Tsunami hazard on the Atlantic coastline is dominated by poorly constrained far-field subduction sources; a lesser hazard is posed by near-field continental slope failures similar to the 1929 Grand Banks event. Tsunami hazard on the Arctic coastline is poorly constrained, but is likely dominated by continental slope failures; a hypothetical earthquake source beneath the Mackenzie delta requires further study. We highlight areas susceptible to locally damaging landslide-generated tsunamis, but do not quantify the hazard.
ISSN: 0921-030X

hal-00963614
https://hal.archives-ouvertes.fr/hal-00963614
DOI : 10.1007/s11069-013-0809-5

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The majority of the largest subduction megathrust earthquakes share the common characteristic of rupturing more than one asperity along strike of the margin. Understanding the factors that control coseismic failure of multiple asperities, and thus maximum magnitude, is central for seismic hazard assessment. To investigate the role of asperities size and spacing on maximum magnitude, seismicity rate, and percentage of synchronized ruptures, we use analog models simulating along-strike rupture behavior of megathrust earthquakes. We found negative correlations between the barrier-to-asperity length ratio Db/Da and maximum magnitude and seismicity rate. Db/Da also controls the process of asperities synchronization along the megathrust. A permanent barrier behavior is observed for Db/Da > 0.5. Comparing our experimental results to the Nankai Trough historical seismicity, we propose that the distribution of megathrust frictional heterogeneities likely explains the diversity of earthquakes which occurred there.
ISSN: 0094-8276

hal-01685546
https://hal.archives-ouvertes.fr/hal-01685546
https://hal.archives-ouvertes.fr/hal-01685546/document
https://hal.archives-ouvertes.fr/hal-01685546/file/Corbi_et_al-2017-Geophysical_Research_Letters.pdf
DOI : 10.1002/2017GL074182

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The 856 A.D. Qumis earthquake (M7.9) is the most destructive earthquake to have occurred in Iran, killing more than 200,000 people and destroying the cities of Damghan and the old Parthian capital of Shahr-i Qumis (Hecatompylos). This study combines evidence of historical seismicity with observations of the geomorphology and paleoseismology to provide the first detailed description of active faulting in the Damghan region of the east Alborz mountains, Iran. Regional left-lateral shear is accommodated on the Astaneh, Damghan, and North Damghan faults. Quaternary alluvial fans have been displaced along the Astaneh fault, with 15–20 m stream offsets recording the cumulative displacement over the last two to five earthquakes. A paleoseismology study from a single trench along a 5–10 km segment of the Astaneh fault reveals a rupture prior to 1300 A.D. and significantly later than 600 B.C. Despite the limitations of a single trench in documenting the spatial and temporal evolution of the fault over the late Quaternary, we are nevertheless able to bracket the last event to a time period consistent with the 856 A.D. earthquake. Two older earthquakes were also identified during the Holocene occurring between 600 B.C. and 4600 B.C. and between 4600 B.C. and 9600 B.C. The location of our trench within a bend on the Astaneh fault, which could act as a barrier to rupture propagation, means the three earthquakes recovered from our trench over the Holocene may represent a minimum. Further trenching will reveal how the Astaneh fault ruptures over repeated earthquakes and, consequently, the magnitude and extent of slip during the 856 A.D. earthquake.
ISSN: 0148-0227

hal-00551330
https://hal.archives-ouvertes.fr/hal-00551330
https://hal.archives-ouvertes.fr/hal-00551330v2/document
https://hal.archives-ouvertes.fr/hal-00551330/file/Hollingsworth2010.pdf
DOI : 10.1029/2009JB007185

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
This paper presents a synthesis of a multidisciplinary study carried out along the Nîmes Roman aqueduct, located in the southeast part of France. The study was motivated by archaeologists attempting to explain the partial destructions of only one aerial bridge of the aqueduct (Pont de la Lône). Given its close proximity to the Nîmes seismically active fault, a possible seismic origin for the destructions was invoked. Seismologists and structural engineers thus carried out a variety of field and numerical investigations to test the seismic hypothesis. Supporting field evidence was found first along the aerial bridge section of the aqueduct: broken stalactites, arch warping, cracks and destruction of the bridge just above a breast wall shortly after its construction. Secondly, the underground part of the canal was analysed: irregularity in the thickness of calcite deposits of the canal walls, presence of numerous cracks, horizontal shift of the otherwise linear structure of the canal and presence of calcite twins in the deposits, found only where the canal crosses the Nîmes fault system. Numerical modelling and experimental results show that (1) only the Pont de la Lône would have suffered serious damage under seismic solicitation (assuming an M6 earthquake at 10 km distance). The second aerial bridge, the three levels arches Pont du Gard, an historical monument still standing today, would have suffered less damage, due to its very different fundamental frequency of around 0.4 Hz, far from the amplified seismic near-field spectrum; (2) the numerical models also show that a fall of the canal wall would require a higher magnitude event (M > 6); (3) the presence of calcite twinning requires a differential static stress of 4 MPa or greater, which can only be achieved very close to the fault rupture of a M > 6 earthquake; (4) finally, local surface rupturing of such a fault would also corroborate the hypothesis that the observed offset of the canal may be partly seismically induced. Although other possible origins for each individual evidence may not be excluded, the observed spatiotemporal concentration of architectural/geological anomalies together with the numerical results allow us to support a possible co-seismic origin for these disorders, indirectly attesting to the potential seismic activity (M > 6) of the nearby Nîmes fault. Furthermore, following the conclusions of archaeological studies, the disorders occurred between 250 and 350 year AD, thus providing timing for this possible seismic event, an essential parameter in seismic hazard analysis. These results validate the archaeo-seismological approach as a tool that may help improve the knowledge of major infrequent earthquakes in areas of moderate seismic activity.
ISSN: 0921-030X

hal-00379064
https://hal.archives-ouvertes.fr/hal-00379064
DOI : 10.1007/s11069-008-9276-9

Éditeur(s) : Elsevier
Résumé : We describe for the first time a set of large active thrusts and folds near the foot of the easternmost Algerian margin, Western Mediterranean, from swath bathymetry and high-resolution seismic data acquired in 2005 during the Maradja2/Samra cruise. This active system resumes a previous passive margin and creates growth strata deposition on the limbs of large folds, resulting in the development of perched basins at the foot of the margin since less than similar to 1 Ma. They form a set of overlapping fault segments verging toward the Algerian basin, in a way similar to what has been observed off eastern Algiers on the rupture zone of the 2003 Mw 6.8 Boumerdes earthquake. The horizontal shortening rate across large folds is estimated to be of the order of 1 mm/yr. Although no historical earthquakes are reported here, these fault segments could have been responsible for large (M similar to 7.5) events in the past. This young tectonic system further supports the hypothesis of subduction inception of the Neogene oceanic lithosphere in the context of the Africa-Eurasia convergence.
Marine Geology (0025-3227) (Elsevier), 2009-06 , Vol. 261 , N. 1-4 , P. 17-32

Droits : 2009 Published by Elsevier Inc.
http://archimer.ifremer.fr/doc/2009/publication-6850.pdf
DOI:10.1016/j.margeo.2008.05.016
http://archimer.ifremer.fr/doc/00000/6850/

Éditeur(s) : HAL CCSD
Résumé : The Astaneh fault with a length of more than 75 km is located in NW of Damghan. Morphotectonic investigation along the Astaneh fault and left - lateral displacement in quaternary deposits shows that, Astaneh is an active fault. It is necessary to recognize paleoseismicity of Astaneh fault because, this fault is located in seismic zone of Komes historical earthquake with Ms=7.9 (Ambraseys & Melville, 1982). Many people (more than 45000) were killed in Damghan city in Komes historical earthquake. In this paper, 4-5 paleo events along the Astaneh fault are presented through paleoseismological investigation.
Geosciences Scientific Quarterly Journal

hal-00854396
https://hal.archives-ouvertes.fr/hal-00854396

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
No major earthquake occurred in North Chile since the 1877 Mw 8.6 subduction earthquake that produced a huge tsunami. However, geodetic measurements conducted over the last decade in this area show that the upper plate is actually deforming, which reveals some degree of locking on the subduction interface. This accumulation of elastic deformation is likely to be released in a future earthquake. Because of the long elapsed time since 1877 and the rapid accumulation of deformation (thought to be 6-7 cm yr−1), many consider this area is a mature seismic gap where a major earthquake is due and seismic hazard is high. We present a new Global Positioning System (GPS) velocity field, acquired between 2008 and 2012, that describes in some detail the interseismic deformation between 18°S and 24°S. We invert for coupling distribution on the Nazca-South America subduction interface using elastic modelling. Our measurements require that, at these latitudes, 10 to 12 mm yr−1 (i.e. 15 per cent of the whole convergence rate) are accommodated by the clockwise rotation of an Andean block bounded to the East by the subandean fold-and-thrust belt. This reduces the accumulation rate on the subduction interface to 56 mm yr−1 in this area. Coupling variations on the subduction interface both along-strike and along-dip are described. We find that the North Chile seismic gap is segmented in at least two highly locked segments bounded by narrow areas of weak coupling. This coupling segmentation is consistent with our knowledge of the historical ruptures and of the instrumental seismicity of the region. Intersegment zones (Iquique, Mejillones) correlate with high background seismic rate and local tectonic complexities on the upper or downgoing plates. The rupture of either the Paranal or the Loa segment alone could easily produce a Mw 8.0-8.3 rupture, and we propose that the Loa segment (from 22.5°S to 20.8°S) may be the one that ruptured in 1877.
ISSN: 0956-540X

hal-00941279
https://hal.archives-ouvertes.fr/hal-00941279
DOI : 10.1093/gji/ggt183