Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
Earth deformation is a multi-scale process ranging from seconds (seismic deformation) to millions of years (tectonic deformation). Bridging short- and long-term deformation and developing seismotectonic models has been a challenge in experimental tectonics for more than a century. Since the formulation of Reid's elastic rebound theory 100 years ago, laboratory mechanical models combining frictional and elastic elements have been used to study the dynamics of earthquakes. In the last decade, with the advent of high-resolution monitoring techniques and new rock analogue materials, laboratory earthquake experiments have evolved from simple spring-slider models to scaled analogue models. This evolution was accomplished by advances in seismology and geodesy along with relatively frequent occurrences of large earthquakes in the past decade. This coincidence has significantly increased the quality and quantity of relevant observations in nature and triggered a new understanding of earthquake dynamics. We review here the developments in analogue earthquake modelling with a focus on those seismotectonic scale models that are directly comparable to observational data on short to long timescales. We lay out the basics of analogue modelling, namely scaling, materials and monitoring, as applied in seismotectonic modelling. An overview of applications highlights the contributions of analogue earthquake models in bridging timescales of observations including earthquake statistics, rupture dynamics, ground motion, and seismic-cycle deformation up to seismotectonic evolution.
ISSN: 1869-9510

hal-01553120
https://hal.archives-ouvertes.fr/hal-01553120
https://hal.archives-ouvertes.fr/hal-01553120/document
https://hal.archives-ouvertes.fr/hal-01553120/file/rosenau2017.pdf
DOI : 10.5194/se-8-597-2017

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The contourite depositional system (CDS) along the southwestern Iberian Margin (SIM), within the Gulf of Cadiz and offshore areas of western Portugal bear the unmistakable signal of Mediterranean Outflow Water (MOW) exiting the Strait of Gibraltar. This locality records key information concerning the effects of tectonic activity on margin sedimentation, the effects of MOW dynamics on Atlantic circulation, and how these factors may have influenced global climate. Over the last four decades, numerous studies have been conducted on the late Miocene, Pliocene and Quaternary sedimentary stacking pattern of Neogene basins along the SIM for both academic and resources exploration purposes. However, understanding of the region rests primarily on basic seismic stratigraphy calibrated with limited data from only a few exploration wells. The Integrated Ocean Drilling Program (IODP) Expedition 339 recently drilled five sites in the Gulf of Cadiz and two sites on the western Iberian margin. The integration of core and borehole data with other geophysical databases leads us to propose a new stratigraphic framework. Interpretation of IODP Exp. 339 data along with that from industry sources and onshore outcrop analysis helps refine our understanding of the SIM's sedimentary evolution.We identify significant changes in sedimentation style and dominant sedimentary processes, coupled with widespread depositional hiatuses along the SIM within the Cadiz, Sanlucar, Doñana, Algarve and Alentejo basins. Following the 4.5 Ma cessation of a previous phase of tectonic activity related to the Miocene–Pliocene boundary, tectonics continued to influence margin development, downslope sediment transport and CDS evolution. Sedimentary features indicate tectonic pulses of about 0.8–0.9 Ma duration with a pronounced overprint of ~ 2–2.5 Ma cycles. These more protracted cycles relate to the westward rollback of subducted lithosphere at the convergent Africa-Eurasia plate boundary as its previous NW–SE compressional regime shifted to a WNW–ESE direction. Two major compressional events affecting to the Neogene basins at 3.2–3 Ma and 2–2.3 Ma help constrain the three main stages of CDS evolution. The stages include: 1) the initial-drift stage (5.33–3.2 Ma) with a weak MOW, 2) a transitional-drift stage (3.2–2 Ma) and 3) a growth-drift stage (2 Ma-present time) with enhanced MOW circulation into the Atlantic and associated contourite development due to greater bottom-current velocity. Two minor Pleistocene discontinuities at 0.7–0.9 Ma and 0.3–0.6 Ma record the effects of renewed tectonic activity on basin evolution, appearing most prominently in the Doñana basin. Several discontinuities bounding major and minor units appear on seismic profiles. Quaternary records offer the clearest example of this, with major units of about 0.8–0.9 Ma and sub-units of 0.4–0.5 Ma. Sedimentation is controlled by a combination of tectonics, sediment supply, sea-level and climate. This research identifies time scales of tectonic controls on deep-marine sedimentation, specifically over periods of 2.5–> 0.4 Ma. Shorter-term climatic (orbital) mechanisms control sedimentation at time scales of ≤ 0.4 Ma. The role of bottom water circulation and associated processes in shaping the seafloor and controlling the sedimentary stacking pattern on continental margins has to be seriously reconsidered in future multidisciplinary studies. This is not only because of the common occurrence of sandy contourite deposits in deep water setting and their economic interest for hydrocarbon exploration, but principally because they archive the heartbeat of the interior Earth and therefore have important sedimentary and paleoceanographic implications.
ISSN: 0025-3227

hal-01356166
https://hal.archives-ouvertes.fr/hal-01356166
DOI : 10.1016/j.margeo.2015.09.013

Éditeur(s) : HAL CCSD
Résumé : International audience
This paper aims to demonstrate that the use of a modern tool, the GPS (Global PositioningSystem), can significantly improve our understanding of active faults and their seismic cycle. We focus on theNorth-Caribbean plate boundary, specifically in the Dominican Republic, and present some quantificationsof velocities that result from measurements that have been made possible by the instrumentation of the areaby a consortium of researchers from France, the USA and the Dominican Republic, since 1994. Then, wediscuss the velocities in terms of seismic potential of the regional major faults.
Cet article présente comment l'utilisation d'un outil moderne, le GPS (Global Positioning System) peut apporter des éléments significatifs dans la connaissance des failles actives et de leur cycle sismique. Nous nous intéressons ici à la frontière de plaque Nord-Caraibe, en République Dominicaine, et présentons des quantifications de vitesses de déplacement obtenues grâce à l'instrumentation de la zone depuis 1994 par un groupe de chercheurs français, états-uniens et dominicains. Les résultats sont ensuite discutés en termes d'aléas sismologiques des failles majeures.
ISSN: 2551-6116

hal-01537725
https://hal.univ-antilles.fr/hal-01537725
https://hal.univ-antilles.fr/hal-01537725/document
https://hal.univ-antilles.fr/hal-01537725/file/Mazabraud-et-Forissier-2007.pdf

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : This paper presents an inversion method using the interseismic velocity field to determine effective rigidity of the lithosphere. The method is based on the minimization of a cost function defined as the quadratic measure of the difference between measured and modelled velocity fields on a discrete set of points. The continuous mapping of the rigidity is fulfilled with a limited set of parameters and the forward solution is achieved using a plane stress finite element code. The computation of the cost function gradient in the parameters' space allows one to iteratively find the best parameters set through a suitable optimization algorithm.;We first design a benchmark including an abrupt rigidity variation that cannot be described by a continuous function. For such a case, we show that increasing the number of parameters is a way to accurately describe sharp variations of the rigidity map. Then, we use a dense GPS velocity field over the southwestern United States to estimate the corresponding rigidity variations for different spatial resolutions of the parameters' grid. We analyse the conceptual and practical difficulties associated with our methodology. Finally, rigidity maps obtained by our inversion method in southwestern United States and particularly across the San Andreas Fault System are reviewed and compared to current plate rigidity estimates and geophysical data over this area.
ISSN: 0956-540X

hal-00669897
https://hal.archives-ouvertes.fr/hal-00669897
DOI : 10.1111/j.1365-246X.2011.05192.x

Éditeur(s) : Elsevier Sci Ltd
Résumé : A detailed morphological analysis of the outer shelf and continental slope of the Western Gulf of Lion is presented, based on swath bathymetry data together with sub-bottom profiles and high resolution seismic reflection profiles. These data reveal two main erosive features, of very different dimensions: the axial incision and the canyon's major valley. The height of axial incisions' flanks with respect to the canyon deepest point (the thalweg) ranges from 40 to 150 m. It creates a small axial erosive path within the canyon's major valley, which is typically bounded by flanks of more than 700 m in height. We interpret the axial incision observed in the sea floor as the imprint of turbidity currents that eroded the floor of canyons during phases of connection to rivers (hyperpycnal turbidity current). Such currents are most likely to have formed during the Last Glacial Maximum (LGM) as both proximity of the shoreline (due to the lowstand of sea level) and high detrital sediment supply (due to glacial abrasion upstream) increased the flow of sediments delivered to the canyon heads. Fossil axial incisions, observed in seismic lines, are related to equivalent conditions. The axial incision, however, has a key influence on canyon evolution as it triggers mass wasting of different sizes that affect the canyon's major valley (head and flanks). We interpret the geometry of the canyon's major valley as the result of recurrent activity of axial incisions. These periods of activity occurred during low sea levels at glacial maxima and show a cyclicity of 100,000 years for the last 400,000 years.
Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2005-06 , Vol. 22 , N. 6-7 , P. 805-826

Droits : 2005 Elsevier Ltd All rights reserved
http://archimer.ifremer.fr/doc/2005/publication-353.pdf
DOI:10.1016/j.marpetgeo.2005.03.011
http://archimer.ifremer.fr/doc/00000/353/

Éditeur(s) : Elsevier Sci Ltd
Résumé : A multi-scale global hindcast of ocean waves is presented that covers the years 1994-2012, based on recently published parameterizations for wind sea and swell dissipation [Ardhuin, F., Rogers, E., Babanin, A., Filipot, J.-F., Magne, R., Roland, A., van der Westhuysen, A., Queffeulou, P., Lefevre, J.-M., Aouf, L., Collard, F., 2010. Semi-empirical dissipation source functions for wind-wave models: Part I. Definition, calibration and validation. J. Phys. Oceanogr. 40 (9), 1917-1941]. Results from this hindcast include traditional wave parameters, like the significant wave height and mean periods, and we particularly consider the accuracy of the results for phenomenal sea states, with significant heights above 14 m. Using unbiased winds, there is no evidence of a bias in wave heights even for this very high range. Various spectral moments were also validated, including the surface Stokes drift and mean square slopes that are relevant for wave-current interactions modelling and remote sensing, and also spectra of seismic noise sources. The estimation of these parameters is made more accurate by the new wave growth and dissipation parameterizations. Associated air-sea fluxes of momentum and energy are significantly different from what is obtained with the WAM-Cycle 4 parameterization, with a roughness that is practically a function of wind speed only. That particular output of the model does not appear very realistic and will require future adjustments of the generation and dissipation parameterizations.
Ocean Modelling (1463-5003) (Elsevier Sci Ltd), 2013-10 , Vol. 70 , P. 174-188

Droits : 2012 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00155/26582/25477.pdf
DOI:10.1016/j.ocemod.2012.12.001
http://archimer.ifremer.fr/doc/00155/26582/

Éditeur(s) : HAL CCSD
Résumé : In this work on a complete transect of the west‐central Pyrenees, we combine low temperature thermochronology (apatite fission tracks, AFT) with a detailed structural analysis to describe vertical movements related to the thrusting system evolution, and to determine the influence of the latter on the sedimentation/burial/exhumation cycle of thesynorogenic deposits of the southern foreland basin (Jaca and Ainsa basins). AFT analysis from a transect of the south‐Pyrenean basin show the southward decrease of the fission track reset level from the southern edge of the Axial Zone to the South‐Pyreneanfrontal thrust, implying the southwards decrease of the burial amount from more than 5kmin the north to less than 3km in the south assuming an average geothermal gradient of 25°C.km‐1. The structural setting of the Jaca basin attests that the burial of the synorogenicsediments was mainly due to the sedimentary accumulation. AFT data from the northernpart of the basin display a late Oligocene‐early (middle) Miocene cooling event. Newinterpretation of industrial seismic reflection profiles across the Jaca basin suggests that the Oturia thrust is rooted in the Bielsa basement thrust, responsible for the early (‐middle) Miocene out‐of‐sequence tectonic reactivation of the southern flank of the Axial Zone (Jolivet et al., 2007). These results reveal a lower Miocene (Burdigalian ‐?Langhian) out‐of sequence episode of tectonic activity of the interior of the south‐Pyrenean foreland basin. AFT data from the Axial Zone and the North‐Pyrenean Zone confirm the general southwardmigration of the thrusting system, and also bring evidence of the late Oligocene‐lowe rMiocene out‐of‐sequence tectonic reactivation of the northern flank of the Axial Zone. All these results attest of a late Oligocene‐lower Miocene (Burdigalian‐?Langhian) "pop‐up" reactivation of the inner part of the west‐central Pyrenees, younger than the sealing of thesouth‐Pyrenean front (Aquitanian‐?Burdigalian) which is classically considered to mark the end of the Pyrenean compression. These results lead us to propose a new crustal scale evolution model of the west‐central Pyrenees in 3 stages: (i) From the Late Cretaceous to themiddle Eocene, the orogenic prism is characterised by the absence of relief, related to theinversion of Cretaceous extensional structures leading to the accretion of thin crustal units; (ii) The late Eocene‐Oligocene stage corresponds to the continental collision, marked by the creation of important relief associated with the accretion of thick crustal units; (iii) During the early Miocene, the inner part of the Pyrenean wedge is tectonically reactivated.
Ce travail de thèse concerne une transversale complète des Pyrénées centro-occidentales, où on a combiné la thermochronologie basse température (traces de fission sur apatites, TFA) avec une analyse structurale détaillée pour décrire les mouvements verticaux associés à l'évolution du système chevauchant, et pour déterminer l'influence de ce dernier sur le cycle sédimentation/enfouissement/exhumation des dépôts synorogéniques du bassin d'avant‐chaine sud (bassins de Jaca et Ainsa). L'analyse TFA complète les données déjà publiées dans la Zone Axiale et la Zone Nord‐Pyrénéenne, e tconstitue la première étude de ce genre dans un bassin d'avant‐chaîne pyrénéen. Les données TFA sur la transversale du bassin sud‐pyrénéen montrent une diminution vers le sud du degré d'effacement des traces de fission, traduisant la diminution vers le sud de la quantité d'enfouissement, supérieure à 5 km au nord et inférieure à 3 km au sud dans l'hypothèse un géotherme de 25°.km‐1. Le contexte géologique montre que l'enfouissement est principalement lié à l'accumulation des dépôts synorogéniques. Les données TFA de lapartie nord du bassin montrent un refroidissement d'âge Oligocène supérieur‐Miocèneinferieur (moyen). Par ailleurs, une nouvelle interprétation de profils de sismiques réflexiondans le bassin de Jaca montre que le chevauchement d'Oturia s'enracine dans lechevauchement de socle de Bielsa, responsable de l'exhumation tectonique hors‐séquencedu bord sud de la Zone Axiale au Miocène inférieur (‐moyen) (Jolivet et al., 2007). Cesrésultats attestent donc de l'exhumation tectonique hors‐séquence au Miocène inférieur (Burdigalien‐ ?Langhien) de la partie nord du bassin d'avant‐chaine sud‐pyrénéen. Des données TFA obtenues dans la Zone Axiale et la Zone Nord‐Pyrénéenne confirment lamigration générale vers le sud du système chevauchant, et mettent également en évidencela réactivation tectonique hors‐séquence du bord nord de la Zone Axiale à l'Oligocèneterminal‐Miocène inférieur. L'ensemble de ces résultats atteste donc de la réactivation en " pop‐up " de la parties interne des Pyrénées centre‐ouest à l'Oligocène supérieur‐Miocèneinférieur (Burdigalien‐ ?Langhien), postérieurement au scellement du front sud‐pyrénéen (Aquitanien‐ ?Burdigalien) classiquement considéré comme marquant la fin de lacompression pyrénéenne. Ces données nous ont permis de proposer un nouveau modèle d'évolution crustale des Pyrénées centro‐occidentales en 3 grandes étapes : (i) du Crétacé supérieur à l'Eocène moyen, le prisme est caractérisé par une absence de relief, en lien avec l'inversion de structures extensives crétacées conduisant à l'accrétion de petites écailles crustales ; (ii) la période Eocène supérieur‐Oligocène correspond à la collision continentale proprement dite, et est marquée par la création d'importants reliefs associés à l'accrétion d'épaisses unités crustales ; (iii) au Miocène inférieur, la partie interne du prisme pyrénéen est réactivée.
https://tel.archives-ouvertes.fr/tel-00772154

Droits : info:eu-repo/semantics/OpenAccess
tel-00772154
https://tel.archives-ouvertes.fr/tel-00772154
https://tel.archives-ouvertes.fr/tel-00772154/document
https://tel.archives-ouvertes.fr/tel-00772154/file/thesemeresse.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We use 36Cl surface exposure dating to determine the slip release pattern over the last ~ 15 kyr for the Velino-Magnola fault, a major active normal fault in Central Italy. We sampled the fault at five well-separated sites along its length, and modeled the 36Cl concentrations measured in the 376 samples. We find that the fault broke in at least 9 large earthquakes that occurred in two 5-6 ka-long supercycles. Each cycle included a 4-5 ka-long phase of relative quiescence, followed by a cluster of at least 3 large earthquakes or earthquake sequences that released most of the accumulated strain in ~ 1 ka. All 9 identified events broke the entire fault and produced maximum surface slips of 2-3 m. Though the Velino-Magnola fault seems presently in a stage of relative quiescence, it may re-enter a phase of paroxysmal seismic activity in a few hundred of years
ISSN: 0012-821X

hal-00667280
https://hal.archives-ouvertes.fr/hal-00667280
DOI : 10.1016/j.epsl.2011.05.022

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Maguelone shore extends along the northern coast of the Gulf of Lions, west of the Rhone Delta and east of high-gradient coastal streams that have provided most of the clastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km-wide area is constituted by a small coastal watershed (15 km long) in low-lying carbonate hills, a kilometre-wide marsh, a sandy beach barrier and a shoreface experiencing local low sedimentation rates. This onshore-offshore transition zone is a key area to understand the relationships between erosion, by-pass, deposition and preservation processes. Unlike the neighbouring Rhone deposits that display numerous thick deltaic sequences related to a continuous sediment flux, the Maguelone shore exhibits peculiar sedimentary bodies. The analysis of about 250 km of new VHR seismic profiles acquired over the study area, 9 short cores and outcrops data allowed us to determine the three-dimensional high-resolution geometry of the coastal system tracts from Quaternary to present-day. This revealed dominant denudation processes in the Upstream catchments associated with the formation of incised valleys during Quaternary lowstands. In addition, this study investigates the erosion and deposition mechanisms controlled by littoral hydrodynamics that have been taken place on this shore since the last transgression. In particular, metre-high and hundreds of metre-long sandy bodies constructed by alongshore hydrodynamics were identified and their effect on the morphodynamics of the whole littoral system is discussed. The Maguelone shore can be used as an experimental study for onshore/offshore dynamics under the influence of microtidal wave/current hydrodynamics and very low river-derived sediment flux during a eustatic cycle. Geometry of system tracts across flood plain to shoreface is usually considered to be controlled by relative sea-level changes, and is successfully analysed with 2D sequence stratigraphy cross-shore models. It is observed that in areas like the Maguelone shore, traditional sequence stratigraphy methods might not be fully relevant and need to integrate alongshore hydrodynamical processes.
ISSN: 0025-3227

hal-00421060
https://hal.archives-ouvertes.fr/hal-00421060
DOI : 10.1016/j.margeo.2009.06.008

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : The Maguelone shore extends along the northern coast of the Gulf of Lions margin, West of the Rhone delta and East of some high gradient coastal streams that have been providing most of the elastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km wide area comprises an onshore small coastal watershed (15 km long) in low-lying carbonate hills, kilometer wide marshes, sandy beach and shoreface featuring local low sedimentation. Deposit architecture in such a coastal zone records dynamics of incised valley fill under the influence of rivers and wave/current hydrodynamics in a microtidal environment during an eustatic cycle.;A detailed analysis of about 250 km of very high resolution seismic profiles, tens of cores and outcrops data revealed the evolution of the Maguelone coastal system from Late-Quaternary to present-day. It highlighted also dominant denudation processes in the upstream catchments associated to the formation of incised valley seaward during Quaternary. Combination of this inherited morphology together with hydrodynamics controlled the lagoonal environment evolution since the last transgression. In particular, the Maguelone shore is characterized by the formation of built-over-rias lagoonal systems and records an evolution from partially protected lagoon to isolated lagoon environment. These two stages of lagoon evolution correspond to distinct deposit environments. Correlation of fauna contents with deposit geometry improves lagoonal environment models.
EISSN: 1777-5817

hal-00486370
https://hal.archives-ouvertes.fr/hal-00486370
DOI : 10.2113/gssgfbull.181.2.211

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
ISSN: 0956-540X

hal-00789114
https://hal.archives-ouvertes.fr/hal-00789114
DOI : 10.1093/gji/ggs085

Éditeur(s) : American Geophysical Union
Résumé : Thick forced regressive units on the wide continental shelf of the Gulf of Lions (western Mediterranean) recorded the composite effect of sea level changes during the Quaternary. They are mostly composed of coastal siliciclastic and bioclastic wedges showing clinoform geometry. These deposits have been intensively explored through high-resolution seismic investigations, but only recently it was possible to ground truth seismic interpretations, based on a long (100 m) borehole that crossed the succession and recovered a large part of the mainly sandy deposits (similar to 84% recovery). A multiproxy analysis of the sedimentary succession shows that (1) the stratal architecture of the shelf margin is defined by major bounding surfaces that are polygenic erosion surfaces associated with coarse-grained material incorporating abundant and diverse shells, including cold-water fauna (presently absent from the Mediterranean Sea). Between each surface, coarsening upward units with steep (up to 5 degrees) foresets are made of massive (more than 20 m thick) sands with possible swaley and hummocky cross-stratification, passing seaward to sands with muddy intervals and, further offshore, alternating highly boiturbated sands and silts. Each prograding wedge corresponds to a forced-regressive shoreface (or delta front/prodelta), deposited during the overall sea level falls occurring at (relatively slow) interglacial/glacial transition and therefore represents the record of 100 ka cyclicity. Higher-frequency Milankovitch cyclicities are also probably represented by distinct shoreface/delta front wedges; (2) detailed examination of the architecture and chronostratigraphy of the most recent sequence shows that minor bounding surfaces, corresponding to abrupt shallowing of sedimentary facies, separate downward stepping parasequences within the last 100 ka sequence. These events are in phase with millennial-scale glacial climatic and sea level variability, the downward shift surfaces corresponding to the falls during the coldest stadials. These deposits provide a comprehensive and well-constrained Pleistocene analog to the numerous shoreface deposits attributed to falling-stage systems tracts recognized in ancient stratigraphic records, studied at the outcrop scale.
Geochemistry Geophysics Geosystems - G3 (1525-2027) (American Geophysical Union), 2008-11 , Vol. 9 , N. Q11R05 , P. NIL_40-NIL_66

Droits : 2008 American Geophysical Union
http://archimer.ifremer.fr/doc/2008/publication-4929.pdf
DOI:10.1029/2007GC001854
http://archimer.ifremer.fr/doc/00000/4929/

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
P>The Strait of Hormuz area is a transition zone between the continental collision of the Zagros (west) and the subduction of an oceanic part of the Arabian Plate beneath the Makran wedge (east). Geology and recent GPS measurements indicate that about 15 mm yr-1 of relative motion in N10 degrees E direction is accommodated by two major fault systems: (1) the NNW-trending Minab-Zendan-Palami (MZP) fault system that connects the Main Zagros Thrust (MZT) to the inner Makran thrust system and the Frontal subduction thrust and (2) the N-trending Sabzevaran-Kahnuj-Jiroft (SKJ) fault system that bounds the Jazmurian depression to the west. We use dense GPS measurements along four transects across these fault systems in order to determine the strains spatial distribution. The northern GPS transect confirms the total fault slip rates for both fault systems estimated by the tectonic analyses (about 10 and 7.3 mm yr-1 in N10 degrees direction across the MZP and SKJ fault systems, respectively). For both fault systems, the elastic deformation spreads over shear zones that are several tens of kilometres wide. However, transects located close to latitude 27 degrees N reveal a much narrower shear zone (similar to 10 km) for the MZP fault system. Moreover, we confirm that most of the present-day strain is transferred towards the frontal subduction thrust rather than towards the inner Makran thrusts. In order to complement this new GPS velocity field with spatially dense measurements, we processed a set of ERS radar images by the radar interferometry (InSAR) technique. We used both a 'stacking' and a 'persistant-scatterers' approach to differentiate the ground deformation signal which spatial gradient is expected to be very low, from the atmospheric signal. Results from these interferograms appear to be relatively in agreement with the GPS-determined strain distribution. Nevertheless, they confirm the absence of any superficial creep behaviour since no sharp discontinuity on interferometric phase can be noted on any interferogram. Finally, we use a purely kinematic 'block model' inversion process to calculate slip rates and locking depths for each fault system from our GPS measurements. These models suggest that the relative quiescence over the last 200 yr has certainly produced a slip deficit as high as 2 m. So, we may wonder if the MZP fault system is not late in the interseismic phase of its earthquake cycle.
ISSN: 0956-540X

hal-00429386
https://hal.archives-ouvertes.fr/hal-00429386
DOI : 10.1111/j.1365-246X.2009.04321.x