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P. Bernard P. Briole B. Meyer H. Lyon-Caen J.-M. Gomez C. Tiberi C. Berge R. Cattin D. Hatzfeld C. Lachet B. Lebrun A. Deschamps F. Courboulex C. Larroque A. Rigo D. Massonnet P. Papadimitriou J. Kassaras D. Diagourtas K. Makropoulos G. Veis E. Papazisi C. Mitsakaki V. Karakostas E. Papadimitriou D. Papanastassiou M. Chouliaras G. Stavrakakis 《Journal of Seismology》1997,1(2):131-150
We present the results of a multidisciplinary study of the Ms = 6.2, 1995, June 15, Aigion earthquake (Gulf of Corinth, Greece). In order to constrain the rupture geometry, we used all available data from seismology (local, regional and teleseismic records of the mainshock and of aftershocks), geodesy (GPS and SAR interferometry), and tectonics. Part of these data were obtained during a postseismic field study consisting of the surveying of 24 GPS points, the temporary installation of 20 digital seismometers, and a detailed field investigation for surface fault break. The Aigion fault was the only fault onland which showed detectable breaks (< 4 cm). We relocated the mainshock hypocenter at 10 km in depth, 38 ° 21.7 N, 22 ° 12.0 E, about 15 km NNE to the damaged city of Aigion. The modeling of teleseismic P and SH waves provides a seismic moment Mo = 3.4 1018 N.m, a well constrained focal mechanism (strike 277 °, dip 33 °, rake – 77°), at a centroidal depth of 7.2 km, consistent with the NEIC and the revised Harvard determinations. It thus involved almost pure normal faulting in agreement with the tectonics of the Gulf. The horizontal GPS displacements corrected for the opening of the gulf (1.5 cm/year) show a well-resolved 7 cm northward motion above the hypocenter, which eliminates the possibility of a steep, south-dipping fault plane. Fitting the S-wave polarization at SERG, 10 km from the epicenter, with a 33° northward dipping plane implies a hypocentral depth greater than 10 km. The north dipping fault plane provides a poor fit to the GPS data at the southern points when a homogeneous elastic half-space is considered: the best fit geodetic model is obtained for a fault shallower by 2 km, assuming the same dip. We show with a two-dimensional model that this depth difference is probably due to the distorting effect of the shallow, low-rigidity sediments of the gulf and of its edges. The best-fit fault model, with dimensions 9 km E–W and 15 km along dip, and a 0.87 m uniform slip, fits InSAR data covering the time of the earthquake. The fault is located about 10 km east-northeast to the Aigion fault, whose surface breaks thus appears as secondary features. The rupture lasted 4 to 5 s, propagating southward and upward on a fault probably outcropping offshore, near the southern edge of the gulf. In the shallowest 4 km, the slip – if any – has not exceeded about 30 cm. This geometry implies a large directivity effect in Aigion, in agreement with the accelerogram aig which shows a short duration (2 s) and a large amplitude (0.5 g) of the direct S acceleration. This unusual low-angle normal faulting may have been favoured by a low-friction, high pore pressure fault zone, or by a rotation of the stress directions due to the possible dip towards the south of the brittle-ductile transition zone. This fault cannot be responsible for the long term topography of the rift, which is controlled by larger normal faults with larger dip angles, implying either a seldom, or a more recently started activity of such low angle faults in the central part of the rift. 相似文献
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Record of enhanced late Pliocene tectono‐volcanic activity in the Lesser Antilles forearc basin: Insights into the long‐term behaviour of the Lesser Antilles subduction zone 
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下载免费PDF全文 Jean‐Len Léticée Mélody Philippon Jean‐Jacques Cornée Philippe Münch Lyvane De Min Mélanie Noury Auran Randrianasolo Jean‐Frédéric Lebrun 《地学学报》2017,29(4):245-252
In this study, we investigate the Lesser Antilles forearc basin, focusing on the late Pliocene to Pleistocene sedimentary archives in order to track the occurrence of extreme events triggered by enhanced subduction‐related tectono‐volcanic activity. We identify late Piacenzian deposits covering a major regional erosional surface, displaying sedimentary dykes and large marine boulders embedded in a mixed continental–marine matrix, characteristic of tsunamites. We interpret this episode of platform emersion and the successive cataclysmic deposits as resulting from enhanced tectonic activity at the interface of the subduction zone, synchronous with the initiation of the Lesser Antilles volcanic arc. We then discuss the implications in terms of the mechanical behaviour of the Lesser Antilles subduction zone. 相似文献
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Frédéric Dondin Jean-Frédéric Lebrun Karim Kelfoun Nicolas Fournier Auran Randrianasolo 《Bulletin of Volcanology》2012,74(2):595-607
Kick 'em Jenny volcano is the only known active submarine volcano in the Lesser Antilles. It lies within a horseshoe-shaped
structure open to the west northwest, toward the deep Grenada Basin. A detailed bathymetric survey of the basin slope at Kick
'em Jenny and resulting high-resolution digital elevation model allowed the identification of a major submarine landslide
deposit. This deposit is thought to result from a single sector collapse event at Kick 'em Jenny and to be linked to the formation
of the horseshoe-shaped structure. We estimated the volume and the leading-edge runout of the landslide to be ca. 4.4 km3 and 14 km, respectively. We modelled a sector collapse event of a proto Kick 'em Jenny volcano using VolcFlow, a finite difference code based on depth-integrated mass and momentum equations. Our models show that the landslide can be
simulated by either a Coulomb-type rheology with low basal friction angles (5.5°–6.5°) and a significant internal friction
angle (above 17.5°) or, with better results, by a Bingham rheology with low Bingham kinematic viscosity (0 < ν
B < 30 m2/s) and high shear strength (130 < γ ≤ 180 m2/s2). The models and the short runout distance suggest that the landslide travelled as a stiff cohesive flow affected by minimal
granular disaggregation and slumping on a non-lubricated surface. The main submarine landslide deposit can therefore be considered
as a submarine mass slide deposit that behaved like a slump. 相似文献
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J. Rodriguez A. Bodaghee P. Kaaret J.A. Tomsick E. Kuulkers G. Malaguti P.-O. Petrucci C. Cabanac M. Chernyakova S. Corbel S. Deluit G. Di Cocco K. Ebisawa A. Goldwurm G. Henri F. Lebrun A. Paizis R. Walter L. Foschini 《Monthly notices of the Royal Astronomical Society》2006,366(1):274-282
We report on observations of the X-ray pulsar IGR J16320−4751 (also known as AX J1631.9−4752) performed simultaneously with International Gamma-Ray Astrophysics Laboratory ( INTEGRAL ) and XMM–Newton . We refine the source position and identify the most likely infrared counterpart. Our simultaneous coverage allows us to confirm the presence of X-ray pulsations at ∼1300 s, that we detect above 20 keV with INTEGRAL for the first time. The pulse fraction is consistent with being constant with energy, which is compatible with a model of polar accretion by a pulsar. We study the spectral properties of IGR J16320−4751 during two major periods occurring during the simultaneous coverage with both satellites, namely a flare and a non-flare period. We detect the presence of a narrow 6.4 keV iron line in both periods. The presence of such a feature is typical of supergiant wind accretors such as Vela X-1 or GX 301−2. We inspect the spectral variations with respect to the pulse phase during the non-flare period, and show that the pulse is solely due to variations of the X-ray flux emitted by the source and not due to variations of the spectral parameters. Our results are therefore compatible with the source being a pulsar in a High Mass X-ray Binary. We detect a soft excess appearing in the spectra as a blackbody with a temperature of ∼0.07 keV. We discuss the origin of the X-ray emission in IGR J16320−4751: while the hard X-rays are likely the result of Compton emission produced in the close vicinity of the pulsar, based on energy argument we suggest that the soft excess is likely the emission by a collisionally energized cloud in which the compact object is embedded. 相似文献
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Jean-Len Léticée Auran Randrianasolo Jean-Jacques Cornée Philippe Münch Jean-Frédéric Lebrun Jean-Paul Saint-Martin Michel Villeneuve 《Comptes Rendus Geoscience》2005,337(6):617-624
A major emersion surface (S1) reveals at least a 60-m relative sea-level fall within the ‘Calcaires supérieurs’ of Grande-Terre (Lesser Antilles fore-arc), an Upper Pliocene–Lower Pleistocene reefal unit. We thus divide the ‘Calcaires supérieurs’ into 2 units. S1, together with the transgresssive calcarenitic and the Acropora-rich reefal units on top of it, corresponding to the record of a complete eustatic cycle by the carbonate platform of this active margin. A comparison with the carbonate platform of the Bahama Bank stable margin, allows us to relate S1 to the major emersive event of 1.66 Ma and to infer that its origin is glacio-eustatic. To cite this article: J.-L. Léticée et al., C. R. Geoscience 337 (2005). 相似文献
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F. Pelaez P. Mandrou M. Niel B. Mena N. Vilmer G. Trottet F. Lebrun J. Paul O. Terekhov R. Sunyaev E. Churazov M. Gilfanov D. Denisov A. Kuznetsov A. Dyachkov N. Khavenson 《Solar physics》1992,140(1):121-138
The anti-coincidence shield of the SIGMA telescope aboard GRANAT provides observations of solar X-ray and -ray bursts in the energy range 200 keV–15 MeV. The characteristics of the experiment are presented here as well as the observations of the solar bursts detected during the first year of operation. Among these events, two of these bursts associated respectively with a limb and a disk flare were observed with significant flux above 10 MeV. Advantage is taken of the experiment large detector area to examine fine time structures even at high energies ( 10 MeV). 相似文献