Search

Your search keyword '"Chéry, J."' showing total 102 results
Start Over Author "Chéry, J."
102 results on '"Chéry, J."'

13. GPS network monitors the Western Alps' deformation over a five-year period: 1993–1998

Author

Vigny, C., Chéry, J., Duquesnoy, T., Jouanne, F., Ammann, J., Anzidei, M., Avouac, J.-P., Barlier, F., Bayer, R., Briole, P., Calais, E., Cotton, F., Duquenne, F., Feigl, K. L., Ferhat, G., Flouzat, M., Gamond, J.-F., Geiger, A., Harmel, A., Kasser, M., Laplanche, M., Le Pape, M., Martinod, J., Ménard, G., Meyer, B., Ruegg, J.-C., Scheubel, J.-M., Scotti, O., and Vidal, G.

Published
2002
Full Text
View/download PDF

17. Propagating Geometric Uncertainties from Image Segmentation to Spatial Indicators of Urban Sprawl

Author

Laurent, V.C.E., Saint-Geours, N, Bailly, Jean-Stéphane, Chéry, J.-P, Territoires, Environnement, Télédétection et Information Spatiale (UMR TETIS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-AgroParisTech-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème (UMR LISAH), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), IAMG, Institut de Recherche pour le Développement (IRD)-Institut de Recherche pour le Développement (IRD [ Madagascar])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)

Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Abstract

International audience; Urban sprawl is a crucial issue for governments at all administrative levels. Monitoring urban sprawl requires spatial indicators at varying spatial scales. These indicators integrate information about impervious areas, population census, socioeconomic context, agricultural activities and soil quality. All the input data, however, suffer from uncertainties which affect the accuracy of the spatial indicator maps. In this contribution, we aim to: 1) evaluate the geometric and thematic uncertainties of the impervious areas extracted from remote sensing images, 2) propagate them to the spatial indicators using simulation, and 3) produce uncertainty maps for two spatial indicators: the area consumption per inhabitant, and the dispersion of impervious areas. In the region Languedoc-Roussillon, which covers 27,376 km 2 in the south of France, a methodology exists to obtain impervious polygons by segmentation and classification (S dataset) of 5 m resolution RapidEye imagery. Reference impervious polygons (R dataset) were digitalized on the RapidEye images for 75 randomly selected municipalities. The segmentation accuracy was evaluated using the intersection area of S and R, and the boundary distance distribution signature (BDDS) (Huang and Dom 1995). The BDDS is the histogram of the distance between each vertex of S to the closest vertex of R, calculated using only the polygons of S having more than 50% area overlap with R. In a Monte-Carlo set up, 1,000 simulations of impervious polygons were generated using Gaussian random fields of polar coordinates of the polygon vertices. The corresponding 1,000 spatial indicator maps allowed mapping the uncertainties and calculating confidence intervals for each indicator of urban sprawl.

Published
2014

19. Present-day uplift of the western Alps

Author

Nocquet, J.-M., primary, Sue, C., additional, Walpersdorf, A., additional, Tran, T., additional, Lenôtre, N., additional, Vernant, P., additional, Cushing, M., additional, Jouanne, F., additional, Masson, F., additional, Baize, S., additional, Chéry, J., additional, and van der Beek, P. A., additional

Published
2016
Full Text
View/download PDF

22. Late Pleistocene to Holocene slip rates for the Gurvan Bulag thrust fault (Gobi-Altay, Mongolia) estimated with10Be dates

Author

Ritz, J.-F., Bourlès, D., Brown, E, Carretier, S., Chéry, J., Enhtuvshin, B., Galsan, P., Finkel, R, Hanks, T, Kendrick, K, Philip, H., Raisbeck, G., Schlupp, A., Schwartz, D, Yiou, F., Laboratoire Dynamique de la Lithosphère (LDL), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), The James Franck Institute and Department of Physics, University of Chicago, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Mongolian Academy of Sciences (MAS), Lawrence Livermore National Laboratory (LLNL), US Geological Survey [Pasadena], United States Geological Survey [Reston] (USGS), Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Détection et de Géophysique (CEA) (LDG), DAM Île-de-France (DAM/DIF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and US Geological Survey Lincoln]

Subjects
slip rate, Late Pleistocene, Holocene, thrust fault, 10Be dating, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mongolia
Abstract

We surveyed morphotectonic markers along the central part of the Gurvan Bulag thrust, a fault that ruptured with the Bogd fault during the Gobi-Altay earthquake (1957, M 8.3), to document climatic and tectonic processes along the fault for the late Pleistocene-Holocene period. The markers were dated using 10 Be produced in situ. Two major periods of alluviation ended at 131 ± 20 and 16 ± 4.8 ka. These appear to be contemporaneous with global climatic changes at the terminations of marine isotope stages (MIS) 6 and 2. The vertical slip rates, determined from offset measurements and surfaces ages, are 0.14 ± 0.03 mm/yr over the late Pleistocene-Holocene and between 0.44 ± 0.11 and 1.05 ± 0.25 mm/yr since the end of the late Pleistocene. The higher of these slip rates for the last $16 kyr is consistent with paleoseismic investigations along the fault [Prentice et al., 2002], and suggests that, at the end of late Pleistocene, the fault evolved from quiescence to having recurrence intervals of 4.0 ± 1.2 kyr for surface ruptures with $4 m vertical offset (similar to that of 1957). The inferred recurrence interval is comparable to that of the Bogd fault (3.7 ± 1.3 kyr) suggesting that the two faults may have ruptured together also earlier during the last $16 kyr.

Published
2003
Full Text
View/download PDF

23. The present-day deformation of the central Zagros from GPS measurements

Author

Mohammad Tatar, Hatzfeld, D., Martinod, J., Walpersdorf, A., Ghafori-Ashtiany, M., Chéry, J., Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 1243 Geodesy and Gravity: Space geodetic surveys, 8102 Tectonophysics: Continental contractional orogenic belts, 1206 Geodesy and Gravity: Crustal movements-interplate (8155), [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], ComputingMilieux_MISCELLANEOUS, 8107 Tectonophysics: Continental neotectonics
Abstract

International audience; In 1997 and in 2000, we measured the distances between 14 geodetic benchmarks across the central Zagros mountain belt. The results show that about 10 mm/yr of shortening in the central Zagros is distributed across the mountain belt. This shortening corresponds to roughly 50% of the total convergence between Arabia and Eurasia and is consistent in direction. The Persian Gulf does not deform significantly. The Main Zagros Reverse Fault is not an active kinematic boundary. The internal deformation of the folded belt is rather homogeneous, at the scale of our survey, which does not allow us to detect any individual active blind fault. However, the strain pattern suggests that N-S dextral strike slip faults may accommodate part of the deformation.

Published
2003
Full Text
View/download PDF

24. Late Pleistocene to Holocene slip rates for the Gurvan Bulag thrust fault (Gobi-Altay, Mongolia) estimated with $^{10}$Be dates

Author

Ritz, J. -F, Didier Bourlès, Brown, E. T., Carretier, S., Chéry, J., Enhtuvshin, B., Galsan, P., Finkel, R. C., Hanks, T. C., Kendrick, K. J., Philip, H., Raisbeck, G., Schlupp, A., Schwartz, D. P., Yiou, F., Lorgeril, Jocelyne, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Published
2003

25. Compressional subduction regime and initial arc-continent collision : Numerical modeling

Author

Tang, J.C., Chemenda, A.I., Chéry, J., Lallemand, S., Hassani, R., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géophysique, Tectonique et Sédimentologie, Université Montpellier 2 - Sciences et Techniques (UM2), Timothy B. Byrne, Char-Shine Liu, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]
Abstract

DOI ouvrage : https://doi.org/10.1130/SPE358; International audience; We performed two-dimensional finite-element numerical modeling of subduction to study the deformation and failure pattern of an overriding plate. This plate has elasto-plastic rheology with strain weakening and contains a "volcanic arc" represented in the model as a thinned and rheologically weakened zone. The subducting plate is not modeled directly. Its effect on the overriding plate is simulated by the normal and tangential stresses along the interplate surface, which correspond to the interplate pressure and interplate friction, respectively. Both stresses cause nonhydrostatic (tectonic) compression on this plate. The first approximation for the interplate pressure is derived from previous experimental modeling of subduction of oceanic lithosphere. Numerical modeling shows that the overriding plate fails under the arc along a trenchward-dipping fault. We then vary both the interplate pressure and the interplate friction and show that the failure direction does not change. Subduction of the continental margin modifies (increases) the interplate pressure because of the buoyancy of thick continental crust. The compressive stress in the overriding plate increases. Failure of this plate can occur in the same way as indicated or in the opposite direction along a fault that dips under the arc (away from the trench and toward the ocean. The failure mode depends in particular on the depth of the margin's subduction prior to lithosphere rupture. Failure along a fault dipping toward the continent results in a subduction reversal, whereas failure along a fault dipping toward the ocean is followed by subduction of a forearc block beneath the arc. Both scenarios seem to have natural analogues.We consider one analogue, the ongoing arc-continent collision in Taiwan, and argue that this process occurs according to the second scenario, which involves forearc subduction.

Published
2002

27. Assessing the precision of the iGrav superconducting gravimeter for hydrological models and karstic hydrological process identification.

Author

Fores, B., Champollion, C., Le Moigne, N., Bayer, R., and Chéry, J.

Subjects
GRAVIMETERS (Geophysical instruments), HYDROLOGY, KARST, SUPERCONDUCTORS, GRAVITY, GEOPHYSICS
Abstract

In this paper we present the potential of a new compact superconducting gravimeter (GWR iGrav) designed for groundwater monitoring. At first, 3 yr of continuous gravity data are evaluated and the performance of the instrument is investigated. With repeated absolute gravity measurements using a Micro-g Lacoste FG5, the calibration factor (-894.8 nm s-2 V-1) and the long-term drift of this instrument (45 nm s-2 yr-1) are estimated for the first time with a high precision and found to be respectively constant and linear for this particular iGrav. The low noise level performance is found similar to those of previous superconducting gravimeters and leads to gravity residuals coherent with local hydrology. The iGrav is located in a fully instrumented hydrogeophysical observatory on the Durzon karstic basin (Larzac plateau, south of France). Rain gauges and a flux tower (evapo-transpiration measurements) are used to evaluate the groundwater mass balance at the local scale. Water mass balance demonstrates that the karst is only capacitive: all the rainwater is temporarily stored in the matrix and fast transfers to the spring through fractures are insignificant in this area. Moreover, the upper part of the karst around the observatory appears to be representative of slow transfer of the whole catchment. Indeed, slow transfer estimated on the site fully supports the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. In the last part of the paper, reservoir models are used to characterize the water transfer and storage processes. Particular highlights are done on the advantages of continuous gravity data (compared to repeated campaigns) and on the importance of local accurate meteorological data to limit misinterpretation of the gravity observations. The results are complementary with previous studies at the basin scale and show a clear potential for continuous gravity time-series assimilation in hydrological simulations, even on heterogeneous karstic systems. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

30. Deciphering oblique shortening of central Alborz in Iran using geodetic data

Author

Vernant, P, Nilforoushan, F, Chéry, J, Bayer, R, Djamour, Y, Masson, F, Nankali, H, Ritz, J-F, Sedighi, M, Tavakoli, F, Vernant, P, Nilforoushan, F, Chéry, J, Bayer, R, Djamour, Y, Masson, F, Nankali, H, Ritz, J-F, Sedighi, M, and Tavakoli, F

Abstract

The Alborz is a narrow (100 km) and elevated (3000 m) mountain belt which accommodates the differential motion between the Sanandaj–Sirjan zone in central Iran and the South Caspian basin. GPS measurements of 12 geodetic sites in Central Alborz between 2000 and 2002 allow to constrain the motion of the belt with respect to western Eurasia. One site velocity on the Caspian shoreline suggests that the South Caspian basin moves northwest at a rate of 6±2 mm/year with respect to western Eurasia. North–South shortening across the Alborz occurs at 5±2 mm/year. To the South, deformation seems to extend beyond the piedmont area, probably due to active thrusting on the Pishva fault. We also observe a left-lateral shear of the overall belt at a rate of 4±2 mm/year, consistent with the geological motion observed along E–W active strike-slip faults inside the belt (e.g., the Mosha fault).

Published
2004

31. Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman

Author

Vernant, P, Nilforoushan, F, Hatzfeld, D, Abbassi, M.R, Vigny, C, Masson, F, Nankali, H, Martinod, J, Ashtiani, A, Bayer, R, Tavakoli, F, Chéry, J, Vernant, P, Nilforoushan, F, Hatzfeld, D, Abbassi, M.R, Vigny, C, Masson, F, Nankali, H, Martinod, J, Ashtiani, A, Bayer, R, Tavakoli, F, and Chéry, J

Abstract

A network of 27 GPS sites was implemented in Iran and northern Oman to measure displacements in this part of the Alpine–Himalayan mountain belt. We present and interpret the results of two surveys performed in 1999 September and 2001 October. GPS sites in Oman show northward motion of the Arabian Plate relative to Eurasia slower than the NUVEL-1A estimates (e.g. 22 ± 2 mm yr−1 at N8°± 5°E instead of 30.5 mm yr−1 at N6°E at Bahrain longitude). We define a GPS Arabia–Eurasia Euler vector of 27.9°± 0.5°N, 19.5°± 1.4°E, 0.41°± 0.1° Myr−1. The Arabia–Eurasia convergence is accommodated differently in eastern and western Iran. East of 58°E, most of the shortening is accommodated by the Makran subduction zone (19.5 ± 2 mm yr−1) and less by the Kopet-Dag (6.5 ± 2 mm yr−1). West of 58°E, the deformation is distributed in separate fold and thrust belts. At the longitude of Tehran, the Zagros and the Alborz mountain ranges accommodate 6.5 ± 2 mm yr−1 and 8 ± 2 mm yr−1 respectively. The right-lateral displacement along the Main Recent Fault in the northern Zagros is about 3 ± 2 mm yr−1, smaller than what was generally expected. By contrast, large right-lateral displacement takes place in northwestern Iran (up to 8 ± mm yr−1). The Central Iranian Block is characterized by coherent plate motion (internal deformation <2 mm yr−1). Sites east of 61°E show very low displacements relative to Eurasia. The kinematic contrast between eastern and western Iran is accommodated by strike-slip motions along the Lut Block. To the south, the transition zone between Zagros and Makran is under transpression with right-lateral displacements of 11 ± 2 mm yr−1.

Published
2004
Full Text
View/download PDF

33. GPS network monitors the Arabia-Eurasia collision deformation in Iran

Author

Nilforoushan, Faramarz, Masson, F., Vernant, P., Vigny, C., Martinod, J., Abbasi, M., Nankali, H., Hatzfeld, D., Bayer, R., Tavakoli, F., Ashtiani, A., Doerflinger, E., Daignières, M., Collard, P., Chéry, J., Nilforoushan, Faramarz, Masson, F., Vernant, P., Vigny, C., Martinod, J., Abbasi, M., Nankali, H., Hatzfeld, D., Bayer, R., Tavakoli, F., Ashtiani, A., Doerflinger, E., Daignières, M., Collard, P., and Chéry, J.

Abstract

The rate of crustal deformation in Iran due to the Arabia–Eurasia collision is estimated. The results are based on new global positioning system (GPS) data. In order to address the problem of the distribution of the deformation in Iran, Iranian and French research organizations have carried out the first large-scale GPS survey of Iran. A GPS network of 28 sites (25 in Iran, two in Oman and one in Uzbekistan) has been installed and surveyed twice, in September 1999 and October 2001. Each site has been surveyed for a minimum observation of 4 days. GPS data processing has been done using the GAMIT-GLOBK software package. The solution displays horizontal repeatabilities of about 1.2 mm in 1999 and 2001. The resulting velocities allow us to constrain the kinematics of the Iranian tectonic blocks. These velocities are given in ITRF2000 and also relative to Eurasia. This last kinematic model demonstrates that (1) the north–south shortening from Arabia to Eurasia is 2–2.5 cm/year, less than previously estimated, and (2) the transition from subduction (Makran) to collision (Zagros) is very sharp and governs the different styles of deformation observed in Iran. In the eastern part of Iran, most of the shortening is accommodated in the Gulf of Oman, while in the western part the shortening is more distributed from south to north. The large faults surrounding the Lut block accommodate most of the subduction–collision transition.

Published
2003
Full Text
View/download PDF

37. Present-day deformation of the Pyrenees revealed by GPS surveying and earthquake focal mechanisms until 2011.

Author

Rigo, A., Vernant, P., Feigl, K. L., Goula, X., Khazaradze, G., Talaya, J., Morel, L., Nicolas, J., Baize, S., Chéry, J., and Sylvander, M.

Subjects
EARTHQUAKES, GLOBAL Positioning System, PLATE tectonics, SEISMOLOGY
Abstract

The Pyrenean mountain range is a slowly deforming belt with continuous and moderate seismic activity. To quantify its deformation field, we present the velocity field estimated from a GPS survey of the Pyrenees spanning 18 yr. The PotSis and ResPyr networks, including a total of 85 GPS sites, were installed and first measured in 1992 and 1995-1997, respectively, and remeasured in 2008 and 2010.We obtain a deformation field with velocities less than 1mmyr-1 across the range. The estimated velocities for individual stations do not differ significantly from zero with 95 per cent confidence. Even so,we estimate a maximum extensional horizontal strain rate of 2.0 ± 1.7 nanostrain per year in a N--S direction in the western part of the range. We do not interpret the vertical displacements due to their large uncertainties. In order to compare the horizontal strain rates with the seismic activity, we analyse a set of 194 focal mechanisms using three methods: (i) the 'r' factor relating their P and T axes, (ii) the stress tensors obtained by fault slip inversion and (iii) the strain-rate tensors. Stress and strain-rate tensors are estimated for: (i) the whole data set, (ii) the eastern and western parts of the range separately, and (iii) eight zones, which are defined based on the seismicity and the tectonic patterns of the Pyrenees. Each of these analyses reveals a lateral variation of the deformation style from compression and extension in the east to extension and strike-slip in the west of the range. Although the horizontal components of the strain-rate tensors estimated from the seismic data are slightly smaller in magnitude than those computed from the GPS velocity field, they are consistent within the 2σ uncertainties. Furthermore, the orientations of their principal axes agree with the mapped active faults. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

47. Global Positioning System Network monitors the western Alps

Author

Chéry, J., primary, Vigny, C., additional, Meyer, B., additional, Ferhat, G., additional, Anzidei, M., additional, Bayer, R., additional, Boloh, L., additional, Briole, P., additional, Deschamps, A., additional, Feigl, K. L., additional, Gamond, J. F., additional, Geiger, A., additional, Jouanne, F., additional, Kasser, M., additional, Lepape, M., additional, Martinod, J., additional, Ménard, G., additional, Ruegg, J. C., additional, Scheubel, J. M., additional, and Walch, J. J., additional

Published
1995
Full Text
View/download PDF

48. Morphotectonic and geodetic evidence for a constant slip-rate over the last 45 kyr along the Tabriz fault (Iran).

Author

Rizza, M., Vernant, P., Ritz, J. F., Peyret, M., Nankali, H., Nazari, H., Djamour, Y., Salamati, R., Tavakoli, F., Chéry, J., Mahan, S. A., and Masson, F.

Subjects
MORPHOTECTONICS, GEOLOGIC faults, GEODESY, DEFORMATIONS (Mechanics), GEOMORPHOLOGY, GLOBAL Positioning System
Abstract

Iran is an active continental domain accommodating the convergence between the Arabia and Eurasia plates. In northwestern Iran, deformation between the Central Iranian block and the Caucasus domain is mainly accommodated by right lateral strike-slip on the Tabriz fault. Cities and villages, including the city of Tabriz, have been destroyed by several strong historical earthquakes (M ∼ 7). In this study, we compare the slip-rates estimated from geodetic measurements (radar interferometry and GPS) with those determined by dating a geomorphological offset of an alluvial fan along the Tabriz fault.The GPS measurements along two profiles normal to the Tabriz fault suggest a slip-rate of 7.3 ± 1.3 mm yr−1. The persistent scatterer radar interferometry analysis of Envisat satellite archives from 2003 to 2010 shows a velocity gradient (6 ± 3 mm yr−1) across the Tabriz fault in agreement with GPS results. Moreover, it reveals that most of the area located south of the Tabriz fault is affected by subsidence, and that some sections of the fault probably act as barriers to fluid migration which may have an impact on its mechanical behaviour. West of Tabriz morphotectonic investigations on an alluvial fan surface show a right-lateral cumulative offset of 320 ± 40 m. Luminescence analyses of the coarse matrix alluvial fan deposits provide an age of 46 ± 3 ka. This yields a slip-rate comprised between 6.5 and 7.3 mm yr−1 along this segment. These results suggest that the Late Quaternary slip-rate is in agreement with the present-day slip-rate estimated by geodetic measurements, showing no slip-rate changes during the past 45 000 yr. Short-term variations within the 45 000 yr related to temporal earthquake clustering over few seismic cycles cannot be ruled out, but if they exist, they do not affect the geodetic and the geomorphological estimates. This study is in agreement with previous ones suggesting that long-term slip-rates (i.e. averaged over several tens of seismic cycles) are consistent with geodetic estimated slip-rates (i.e. extrapolated from few years of interseismic observations), and suggests that perturbations of fault slip-rates are related to variations over few seismic cycles. [ABSTRACT FROM AUTHOR]

Published
2013
Full Text
View/download PDF

50. On the impact of topography and building mask on time varying gravity due to local hydrology.

Author

Deville, S., Jacob, T., Chéry, J., and Champollion, C.

Subjects
GRAVIMETRY, TIME-varying systems, HYDROLOGY, TIME series analysis, DATA analysis
Abstract

We use 3 yr of surface absolute gravity measurements at three sites on the Larzac plateau (France) to quantify the changes induced by topography and the building on gravity time-series, with respect to an idealized infinite slab approximation. Indeed, local topography and buildings housing ground-based gravity measurement have an effect on the distribution of water storage changes, therefore affecting the associated gravity signal. We first calculate the effects of surrounding topography and building dimensions on the gravity attraction for a uniform layer of water. We show that a gravimetric interpretation of water storage change using an infinite slab, the so-called Bouguer approximation, is generally not suitable. We propose to split the time varying gravity signal in two parts (1) a surface component including topographic and building effects (2) a deep component associated to underground water transfer. A reservoir modelling scheme is herein presented to remove the local site effects and to invert for the effective hydrological properties of the unsaturated zone. We show that effective time constants associated to water transfer vary greatly from site to site. We propose that our modelling scheme can be used to correct for the local site effects on gravity at any site presenting a departure from a flat topography. Depending on sites, the corrected signal can exceed measured values by 5–15 μGal, corresponding to 120–380 mm of water using the Bouguer slab formula. Our approach only requires the knowledge of daily precipitation corrected for evapotranspiration. Therefore, it can be a useful tool to correct any kind of gravimetric time-series data. [ABSTRACT FROM PUBLISHER]

Published
2013
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results