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A 3-D Quasi-static Model for a Variety of Slip Behaviors on a Subduction Fault |
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| Authors: | Hitoshi Hirose Kazuro Hirahara |
| Institution: | 1. Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan 2. National Research Institute for Earth Science and Disaster Prevention, 3-1 Tennodai, Tsukuba, Ibaraki, 305-0006, Japan 3. Division of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan |
| Abstract: | — Earthquake faultings have a wide variety of slip behaviors, such as, a log-linear frequency-magnitude relation, characteristic earthquakes, slow slip events, and so on. We report a model which can reproduce a certain variety of observed complex slip behaviors on a fault. Our 3-D model simulates the seismic cycle on a shallow dipping subduction fault in a homogeneous elastic half-space, on which frictional sliding is controlled by a rate- and state-dependent friction law. We find that the behaviors of reproduced seismic cycles depend on a lateral dimension of a seismogenic zone (H) with respect to a constant seismogenic width in dip direction (W). The following three domains appear in the seismic cycle behaviors: (1) Regular, periodic behaviors when H is comparable to W; (2) transitional, quasi-periodic behaviors when H/W~ 3; and (3) complex behaviors when H/W is larger than about 4. The slip behavior in the domain (1) is characterized by a periodical recurrence of a characteristic earthquake, which is centered in strike direction. In the domain (2), although earthquakes are still centered, these recurrence intervals and the sizes are modulated within a certain range. Also, in the domain (3), earthquakes occur not only at the center but at various lateral positions on the seismogenic zone. In this domain, the log-linear frequency-magnitude relations, like the Gutenberg-Richter relation, are produced. Slow slip events also occur at source areas of the earthquakes. It is suggested that a heterogeneous stress distribution at a source region is important, as well as heterogeneities in friction properties on the fault, for understanding the wide variety of slip behaviors in faultings. |
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