A microseismic study in the western part of the Gulf of Corinth (Greece): Implications for large-scale normal faulting mechanisms

被引:249
作者
Rigo, A
LyonCaen, H
Armijo, R
Deschamps, A
Hatzfeld, D
Makropoulos, K
Papadimitriou, P
Kassaras, I
机构
[1] INST PHYS GLOBE,CNRS URA 195 & 1093,F-75252 PARIS 05,FRANCE
[2] UNSA,CNRS,EP 125,UMR GEOSCI AJUR,INST GEODYNAM,F-06560 VALBONNE,FRANCE
[3] UNIV GRENOBLE 1,CNRS URA 733,IRIGM,LGIT,F-38402 ST MARTIN DHERES,FRANCE
[4] UNIV ATHENS,DEPT GEOL,DIV GEOPHYS GEOTHERMY,ATHENS 15784,GREECE
关键词
fault-plane solutions; Greece; Gulf of Corinth; normal faulting; microseismicity;
D O I
10.1111/j.1365-246X.1996.tb04697.x
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We present the results of a dense seismological experiment in the western part of the Gulf of Corinth (Psathopyrgos-Aigion area), one of the most active rifts in the Aegean region for which we have precise tectonic information. The network included 51 digital stations that operated during July and August 1991, covering a surface of 40 x 40 km(2). Among the 5000 recorded events with M(L) ranging between 1.0 and 3.0, we precisely located 774 events, We obtained 148 well-constrained focal mechanisms using P-wave first motions. Of these, 60 also have mechanisms obtained by combining the P-wave first motions with the S-wave polarization directions, The observed seismicity is mainly located between 6 and 11 km depth, Most of the fault-plane solutions correspond to E-W-striking normal faulting, in agreement with the geological evidence, Most of the well-determined mechanisms indicate a nodal plane dipping 10-25 degrees due north and a steep south-dipping plane. A similar asymmetry is also seen in the seismicity distribution and in the overall geological structure of the Corinth Rift. We discuss this evidence and the inference of a deep detachment zone, a structure where the major faults seen at the surface appear to root, A large part of the microseismic activity appears to cluster in regions near the junctions of the main faults with the proposed detachment zone, This feature of the microseismicity is interpreted in terms of stress transfer and stress concentration in regions of probable nucleation of future large earthquakes.
引用
收藏
页码:663 / 688
页数:26
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