open access

https://hdl.handle.net/2115/34908

On the biannually repeating slow-slip events at the Ryukyu Trench, southwestern Japan

英語

2008-11-04

American Geophysical Union

Journal of Geophysical Research. B, Solid earth

113(11)

B11402

Global Positioning System data show that about twenty slow slip events occurred during 1997-2007 in the southwestern part of the Ryukyu Arc, Japan, where large interplate thrust earthquakes are not known to have occurred in spite of relatively fast plate convergence. They recur fairly regularly on one patch of the subduction fault, which is as deep as 20-40 km and mechanically isolated in an uncoupled subduction zone. They have time constants of a month or so, and release seismic moment equivalent of Mw 6.6 on average. This is one of the best recorded sequences of repeating fault slips, with enough events for statistical analyses. They have fairly constant recurrence interval of ~0.5 year but do not show preferred months of occurrence in a year, suggesting that they are not controlled by seasonal forcing. The correlation between intervals and amounts of fault slip show statistically significant time-predictable recurrences. There is one significant disruption in the rhythm, but the stress perturbations due to nearby earthquakes do not appear to play a significant role. This part of the fault might be an altered asperity that used to rupture fast but now slips only slowly due to increased ambient temperature.

学術雑誌論文

Accepted Manuscript

An edited version of this paper was published by AGU. Copyright 2008 American Geophysical Union.

0148-0227

AA10819743