Temporal changes of Group Velocity of Empirical Green's Function from Ambient Seismic Noise Correlation Associated with Two Major Earthquakes in Korean Peninsula
Abstract
Identifying temporal seismic velocity change near epicenter associated with earthquakes is a clue to understand what is happening in fault. In this study, we report temporal change of surface wave group velocity observed over large area associated with 2 major earthquakes in Korea. We applied Phase-Weighted Stacking (PWS) method to retrieve empirical Green's function (EGF) of surface waves between two stations (BUS-ULJ2). The two major earthquakes are located at about center of the two stations. We correlated 8 years continuous seismic data before and after the earthquakes. We calculated Group velocity from the EGF and found seasonal variation of Group velocity which is recently reported as it might be related to seasonal thermo-elastic strain change. As we remove the seasonal variations, the fraction of group velocity (dV/V), definitely increases up to about 1.6 % before earthquakes. However after the earthquakes, the velocity tends to decrease to the original values. This observation can be interpreted by stress changes before and after earthquakes and subsequent stress relaxation effect near the fault rupture zone of upper crust.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T33F0490L
- Keywords:
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- 1242 Seismic cycle related deformations;
- GEODESY AND GRAVITYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICSDE: 8163 Rheology and friction of fault zones;
- TECTONOPHYSICS