TY - JOUR
T1 - Temporal variation of shear-wave splitting parameters before and after the 2008 movri mountain earthquake in northwest peloponnese (Greece)
AU - Giannopoulos, Dimitrios
AU - Sokos, Efthimios
AU - Konstantinou, Konstantinos I.
AU - Lois, Athanasios
AU - Tselentis, G. Akis
PY - 2012
Y1 - 2012
N2 - On June 8, 2008, at 12:25 GMT, a MW 6.4 earthquake, the Movri Mountain earthquake, occurred in the area of northwest Peloponnese, western Greece. The epicenter was located in the municipality of Movri, 35 km southwest of Patras. For this study, a crustal anisotropy analysis was performed in the epicentral area of the Movri Mountain earthquake. Specifically, the shear-wave splitting phenomenon and its temporal evolution in relation to the Movri Mountain earthquake was studied, using the cross-correlation method. The data analysis revealed the presence of shear-wave splitting in the study area. Both before and after the Movri Mountain earthquake, the polarization directions of the fast component of the shear waves followed a general NNW-SSE direction. The observed mean fast polarization direction was not consistent with the regional stress field, which showed a general E-W direction of the maximum horizontal compressive stress. The differences between the estimated fast polarization directions and the properties of the regional stress field suggest the presence of a local stress field in the area around the fault. An increase in time delays was observed soon after the Movri Mountain earthquake. The average value of the delay times before the earthquake was ca. 18 ±2.6 ms, while after the earthquake this was ca. 40 ±4.6 ms. This increase in the time delay indicates changes in the crustal properties, which were possibly caused by variations in the preexisting micro-crack system characteristics related to the Movri Mountain earthquake, and the possible involvement of over-pressured fluids.
AB - On June 8, 2008, at 12:25 GMT, a MW 6.4 earthquake, the Movri Mountain earthquake, occurred in the area of northwest Peloponnese, western Greece. The epicenter was located in the municipality of Movri, 35 km southwest of Patras. For this study, a crustal anisotropy analysis was performed in the epicentral area of the Movri Mountain earthquake. Specifically, the shear-wave splitting phenomenon and its temporal evolution in relation to the Movri Mountain earthquake was studied, using the cross-correlation method. The data analysis revealed the presence of shear-wave splitting in the study area. Both before and after the Movri Mountain earthquake, the polarization directions of the fast component of the shear waves followed a general NNW-SSE direction. The observed mean fast polarization direction was not consistent with the regional stress field, which showed a general E-W direction of the maximum horizontal compressive stress. The differences between the estimated fast polarization directions and the properties of the regional stress field suggest the presence of a local stress field in the area around the fault. An increase in time delays was observed soon after the Movri Mountain earthquake. The average value of the delay times before the earthquake was ca. 18 ±2.6 ms, while after the earthquake this was ca. 40 ±4.6 ms. This increase in the time delay indicates changes in the crustal properties, which were possibly caused by variations in the preexisting micro-crack system characteristics related to the Movri Mountain earthquake, and the possible involvement of over-pressured fluids.
UR - http://www.scopus.com/inward/record.url?scp=84873901672&partnerID=8YFLogxK
U2 - 10.4401/ag-5586
DO - 10.4401/ag-5586
M3 - 期刊論文
AN - SCOPUS:84873901672
SN - 1593-5213
VL - 55
SP - 1027
EP - 1038
JO - Annals of Geophysics
JF - Annals of Geophysics
IS - 5
ER -