Crustal imaging using earthquake sequences as source
Presenter: Haw-Chun Wang Adviser: How-Wei Chen
Abstract
During the 1990s, rising amount and quality of regional seismic networks made earthquake records capable as an alternative source for structural imaging. Because of the lack of active-source data, several studies tried to apply prestack migration algorithm on earthquake seismograms through simplified condition assumptions. The concepts are pretty similar to those of used for seismic surveys, while the differences are the need of taking focal mechanism, reflectivity and anisotropy issues into account. In spite of the studies tend to ignore those properties by asymptotically assuming the condition is acoustic, their efforts still works in certain area. Here in this talk, the concepts would be about methods and applications in area of southern California and Hikurangi slab of New Zealand. The results turn out that this method hugely depends on “dense and coverage” of “source and receiver”. With a small amount (100~500) of well-located earthquake events, it can only resolve area below earthquake swarms within a small offset. However, it gives a view of using nature sources for imaging, and has its potential for larger data set.
References
Chávez-Pérez, S., and Louie, J. N., 1998, Crustal imaging in southern California using earthquake sequences: Tectonophysics, 286, 223-236.
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Louie, J.N., Chavez-Perez, S., Henrys, S.A., and Bannister, S., 2002. Multimode migration of scattered and converted waves for the structure of the Hikurangi slab interface, New Zealand. Tectonophysics, 355, 227–246.