Earth Planets Space, Vol. 60 (No. 10), pp. e17-e20, 2008E-LETTER
Masatoshi Miyazawa1, Emily E. Brodsky2, and Jim Mori1
1Disaster Prevention Research Institute, Kyoto University, Japan
2Department of Earth and Planetary Sciences, University of California, Santa Cruz, California, USA
(Received August 18, 2008; Revised October 4, 2008; Accepted October 9, 2008; Online published October 24, 2008)
Remote triggering of small low-frequency seismic tremor (non-volcanic tremor) near the seismic-aseismic transition zone of subduction zones, by surface waves from large distant earthquakes, has been reported in southwest Japan and the Cascadia region. Recent observed triggering in southwest Japan from three large earthquakes (2003 Tokachi-oki, 2007 Solomon, and 2008 Wenchuan) covering wide azimuthal information provides strong evidence for the influence of fluids in the source area. The Coulomb failure stress analyses suggest the effective friction coefficient is large for southwest Japan and small for the Cascadia region, which could be related to the amount of fluid in the source regions of the low-frequency tremor.
Key words: Dynamic triggering, low-frequency tremor, 2008 Wenchuan earthquake.