Analysis of a high quality seismic catalog reveals that the average of seismic b-values in the crust beneath most part of northeastern Japan island arc decreased from 0.86 between 1984 and 1990, to 0.73 between 1991 and 1995. The two areas with the largest decrease are found to be in the same areas where the coupling between the North American and the Pacific plates is the highest, as suggested by a recent geodetic study. In the same time period, the annual seismic moment release increased by 10 times. In addition, there seems to be a corresponding increase in volcanic activities in the same area. One of the most likely interpretations for the observations is an increase in the subduction rate starting from 1991. The timing of this possible increase in subduction rate is consistent with an apparent increase in global seismic activity.
A. Cao and S. S. Gao, "Temporal Variation of Seismic B-Values beneath Northeastern Japan Island Arc," Geophysical Research Letters, vol. 29, no. 9, pp. 48-1-48-3, American Geophysical Union (AGU), May 2002.
The definitive version is available at http://dx.doi.org/10.1029/2001GL013775
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Seismology; Tectonics; Volcanoes; Seismic moment; Subduction rate; Geophysics; island arc; plate motion; seismic data; subduction; temporal variation; Japan
International Standard Serial Number (ISSN)
Article - Journal
© 2002 American Geophysical Union (AGU), All rights reserved.