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F. Courboulex J. Virieux A. Deschamps D. Gibert A. Zollo 《Geophysical Journal International》1996,125(3):768-780
We propose a two-step inversion of three-component seismograms that (1) recovers the far-field source time function at each station and (2) estimates the distribution of co-seismic slip on the fault plane for small earthquakes (magnitude 3 to 4). The empirical Green's function (EGF) method consists of finding a small earthquake located near the one we wish to study and then performing a deconvolution to remove the path, site, and instrumental effects from the main-event signal.
The deconvolution between the two earthquakes is an unstable procedure: we have therefore developed a simulated annealing technique to recover a stable and positive source time function (STF) in the time domain at each station with an estimation of uncertainties. Given a good azimuthal coverage, we can obtain information on the directivity effect as well as on the rupture process. We propose an inversion method by simulated annealing using the STF to recover the distribution of slip on the fault plane with a constant rupture-velocity model. This method permits estimation of physical quantities on the fault plane, as well as possible identification of the real fault plane.
We apply this two-step procedure for an event of magnitude 3 recorded in the Gulf of Corinth in August 1991. A nearby event of magnitude 2 provides us with empirical Green's functions for each station. We estimate an active fault area of 0.02 to 0.15 km2 and deduce a stress-drop value of 1 to 30 bar and an average slip of 0.1 to 1.6 cm. The selected fault of the main event is in good agreement with the existence of a detachment surface inferred from the tectonics of this half-graben. 相似文献
The deconvolution between the two earthquakes is an unstable procedure: we have therefore developed a simulated annealing technique to recover a stable and positive source time function (STF) in the time domain at each station with an estimation of uncertainties. Given a good azimuthal coverage, we can obtain information on the directivity effect as well as on the rupture process. We propose an inversion method by simulated annealing using the STF to recover the distribution of slip on the fault plane with a constant rupture-velocity model. This method permits estimation of physical quantities on the fault plane, as well as possible identification of the real fault plane.
We apply this two-step procedure for an event of magnitude 3 recorded in the Gulf of Corinth in August 1991. A nearby event of magnitude 2 provides us with empirical Green's functions for each station. We estimate an active fault area of 0.02 to 0.15 km
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Three-dimensional numerical simulation of wind-induced barotropic circulation in the Gulf of Patras 总被引：1，自引：0，他引：1
Nikolaos Th. Fourniotis 《Ocean Engineering》2010,37(4):355-364
The barotropic, wind-induced circulation, which develops in the Gulf of Patras in Western Greece during the winter, is studied using three-dimensional numerical simulations. The simulations are performed using the numerical code MIKE 3 FM (HD). The Gulf's basin is bracketed between two sills, one on the west at the opening with the Ionian Sea and the other on the east at the Straits of Rio-Antirio at the opening with the Gulf of Corinth. The simulations show that the wind-induced flow creates strong currents near the coasts, which determine the sense of rotation of the gyres that develop in the Gulf. Strong currents are also created at the Rio-Antirio Straits. The wind-induced, barotropic currents do not seem to contribute to the direct replenishment of bottom waters, which recirculate between the two sills. Depending on the wind-speed forcing of the flow, the residence time of the waters in the Gulf of Patras is estimated to range from one week to one month. 相似文献
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The Patras, Corinth, and northern Saronic gulfs occupy a 200-km-long, N120° trending Pleistocene rift zone, where Peloponnese drifts away from mainland Greece. The axes of Patras and Corinth basins are 25 km apart and linked by two transfer-fault zones trending N040°. The older one defines the western slope of Panachaïkon mountain, and the younger one limits the narrow Rion–Patras littoral plain. Between these two faults, the ca. 4-km-thick Rion–Patras series dips 20–30° SSW. It is part of the Patras gulf synrift deposits, which pile in an asymmetric basin governed by a fault dipping ca. 25–35° NNE, located in the southern Gulf of Patras. Mapping of this fault to the east in northern Peloponnese shows that it is an inactive north-dipping low-angle normal fault (0° to 30°N), called the northern Peloponnese major fault (NPMF). The structural evolution of the NPMF was different in the gulfs of Patras and Corinth. In the Gulf of Patras, it is still active. In northern Peloponnese, footwall uplift and coeval southward tilting flattened the fault and locked its southern part. Steeper normal faults formed north of the locked area, connecting the still active northern part of the NPMF to the surface. After several locks, the presently active normal faults (Psathopyrgos, Aigion, Helike) trend along the southern shore of the Gulf of Corinth. This migration of faults caused the relative 25 km northward shift of the Corinth basin, and the formation of NE–SW trending transfer-faults between the Corinth and Patras gulfs. 相似文献
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