Repeating earthquakes and quasi-static slip on the plate boundary east off northern Honshu, Japan

We have investigated spatio-temporal variation in small repeating earthquake activity in the 1989 earthquake swarm and used them to infer quasi-static slip distribution on the plate boundary off Sanriku, northern Honshu, Japan. Seismicity and inferred quasi-static slip accelerations propagated to th...

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Bibliographic Details
Published in:Earth, planets and space planets and space, 2004-01, Vol.56 (8), p.803-811
Main Authors: MATSUZAWA, Toru, UCHIDA, Naoki, IGARASHI, Toshihiro, OKADA, Tomomi, HASEGAWA, Akira
Format: Article
Language:English
Subjects:
Acceleration
Cosmochemistry. Extraterrestrial geology
Earth sciences
Earth, ocean, space
Earthquakes
Exact sciences and technology
Plate boundaries
Seismic activity
Seismicity
Slip
Temporal variations
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Summary:We have investigated spatio-temporal variation in small repeating earthquake activity in the 1989 earthquake swarm and used them to infer quasi-static slip distribution on the plate boundary off Sanriku, northern Honshu, Japan. Seismicity and inferred quasi-static slip accelerations propagated to the west and to the south during the swarm activity to trigger the occurrence of the largest earthquake (M7.1). To explain the migration of the seismicity and inferred quasi-static slip acceleration, we propose a conceptual model named the ‘chain reaction model’ in which large earthquakes generate large afterslips and then the afterslips accelerate the ruptures of the nearby asperities to generate the next earthquakes which are also followed by large afterslips, and so on. The model is applicable to a plate boundary where asperities are located sparsely but the afterslip associated with the rupture of an asperity can reach nearby asperities. Aftershock area expansion, which is conspicuous off Sanriku, is also explained by the model. If we can evaluate the slip deficit of a large asperity correctly, we will be able to issue a warning of large earthquake occurrence in some areas when we detect the acceleration of quasi-static slip near the asperity although the prediction is inevitably probabilistic.
ISSN:1343-8832
1880-5981
1880-5981
DOI:10.1186/BF03353087