Combining back-projection and matched filter in detecting offshore seismicity: Application to NE Japan subduction zone

Tian Feng, & Lingsen Meng

Published August 15, 2018, SCEC Contribution #8741, 2018 SCEC Annual Meeting Poster #086

In this project, we combine the Back Projection (BP) imaging and match-filter detection (MF) techniques to improve the capability of detecting offshore events. The MF method searches for similar patterns by cross-correlating waveforms of known template events with continuous seismic records. However, the MF method is heavily relying on known earthquake templates, which are obtained from the routine catalogs that lack events in the offshore region. By including BP-detected events as additional templates in the MF detection, we can potentially improve the picture of offshore seismicity. We studied the 2011 M 9.0 Tohoku-Oki earthquake by performing BP imaging one week following the mainshock first. Comparing with JMA catalog, we detected 710 undocumented new events. We then take them as MF templates and find additional 49924 new events within 60 days after the mainshock. It shows a significant amount of newly detected seismicity outer rise the trench, consistent with positive static Coulomb stress changes induced by mainshock rupture. Also, we are extending the analysis to the two foreshock migration sequences starting ~1 month before the mainshock.

Key Words
Back Projection, Match Filter, Small Earthquakes

Citation
Feng, T., & Meng, L. (2018, 08). Combining back-projection and matched filter in detecting offshore seismicity: Application to NE Japan subduction zone. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology