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

Toru Matsuzawa, Naoki Uchida, Toshihiro Igarashi, Tomomi Okada, Akira Hasegawa

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)803-811
Number of pages9
JournalEarth, Planets and Space
Issue number8
Publication statusPublished - 2004


Dive into the research topics of 'Repeating earthquakes and quasi-static slip on the plate boundary east off northern Honshu, Japan'. Together they form a unique fingerprint.

Cite this