Acceleration of regional plate subduction beneath Kanto, Japan, after the 2011 Tohoku‐oki earthquake. Issue 17 (14th September 2016)

• Record Type: Journal Article
• Authors: Uchida, Naoki; Asano, Youichi; Hasegawa, Akira
• Is Part Of: Geophysical research letters. Volume 43:Issue 17(2016)
• Page Start: 9002
• Page End: 9008
• Publication Date: 2016-09-14
• Subjects: repeating earthquake -- aseismic slip -- Tohoku‐oki earthquake -- Philippine Sea plate -- plate motion -- Kanto earthquake; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL070298
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Two oceanic plates (the Pacific (PA) and Philippine Sea (PH)) subduct beneath the land plate, and they forms deeper (PH‐PA) and shallower (land‐PH) plate boundaries beneath Kanto. Remarkably enhanced seismicity was observed in the densely populated area after the 2011 Tohoku‐oki earthquake, which cannot simply be explained by the southern expansion of the postseismic slip of the earthquake. We examine interplate repeating earthquakes to constrain the relative plate motion across aseismically slipping faults. The repeater slip rates show creep rates in the deeper and shallower boundaries, respectively, increased to 2.4–6.6 times and 1.3–6.2 times the pre‐Tohoku‐oki rates. In addition, the repeater slip directions show no change larger than 4° in the deeper boundary. The interplate creep rates and slip directions suggest that regional movements of both the two plates had accelerated. They probably caused the seismicity increase, frequent slow slips on the shallower boundary, and enhanced probability of larger earthquakes. Key Points: Interplate creep history was estimated by the slip amount and slip direction of small repeating earthquakes Subduction rate of two oceanic plates beneath Kanto both increased after the 2011 Tohoku‐oki earthquake Remarkably enhanced seismicity and frequent occurrence of slow slips after the earthquake are explained by the subduction acceleration