TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 56 (No. 12), pp. 1077-1086, 2004

What controls the occurrence of shallow intraplate earthquakes?

Yoshihisa Iio1, Takeshi Sagiya2, and Yoji Kobayashi3

1Research Center for Earthquake Prediction, Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji 611-0011, Japan
2Research Center for Seismology, Volcanology and Disaster Mitigation, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
3Institute for Geoscience, University of Tsukuba, Tsukuba, Ibaragi 305-0006, Japan

(Received April 30, 2004; Revised October 10, 2004; Accepted December 15, 2004)

Abstract: We simulated the occurrence of both intraplate and interplate earthquakes in a simple spring-slider-dashpot model that includes both types of earthquake faults. We found that recurrence intervals of intraplate earthquakes are not controlled by the velocity of the relative plate motion but by the viscosity in the ductile fault zone, the coefficients of friction of both the interplate and intraplate earthquake faults, and the stress drop of intraplate earthquakes, when the stress drop of intraplate earthquakes is assumed to be only a small part of the total shear stress. These findings may open new avenues for the physics-based long-term forecasting of intraplate earthquakes.
Key words: Intraplate earthquake, lower crust, recurrence interval, ductile fault zone.

Corresponding author E-mail: iio@rcep.dpri.kyoto-u.ac.jp

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