Localized Water Reverberation Phases and its Impact on Back-Projection Images

Thursday, October 5, 2017

12:15 pm

Mitchell 350/372

Sponsored by:
Geophysics Department

Coherent radiators imaged by back-projections (BP) are commonly interpreted as part of the rupture process. Nevertheless, artifacts introduced by structure related phases are rarely discriminated from the rupture process. In this study, we use a calibration event to discriminate between rupture and structure effects. We re-examine the waveforms and BP images of the 2012 Mw 7.2 Indian Ocean earthquake and a calibration event (Mw 6.2). The P wave codas of both events present similar shape with characteristic period of approximately 10 s, which are back-projected as coherent radiators near the trench. S wave BP doesn’t image energy radiation near the trench. We interpret those coda waves as localized water reverberation phases excited near the trench. We perform a 2D waveform modeling using realistic bathymetry model, and find that the steep near-trench bathymetry traps the acoustic water waves forming localized reverberation phases. These waves can be imaged as coherent near-trench radiators with similar features as that in the observations. We present a set of methodologies to discriminate between the rupture and propagation effects in BP images, which can serve as a criterion of subevent identification.

When:
Thursday, October 5, 2017
12:15 pm – 01:15 pm
Where:
Mitchell 350/372
Tags:

Seminar Science 

Audience:
Faculty/Staff, Students, Alumni/Friends, Members
Contact:
650.497.3498, coreyann@stanford.edu