[S-SS16] [JJ] Crustal Structure

[SSS16-09] Earthquake source fault model for Kanto area based on seismic reflection profiling and geologic data

*Tatsuya Ishiyama¹, Hiroshi Sato¹, Naoko Kato¹, Susumu Abe² (1.Earthquake Research Institute, University of Tokyo, 2.Japan Petroleum Exploration Co., Ltd.)

We present a new earthquake fault model for the Kanto region including Tokyo metropolitan area, based on interpretation of the seismic reflection data coupled with geologic data including surface geology and borehole stratigraphy. The Tokyo metropolitan area, underlain by Neogene and Quaternary sediments more than 5 km thick, is currently deformed by blind thrusts that could generate hazardous earthquakes. Deep seismic reflection profiles indicate that newly identified, steeply dipping blind thrusts are reactivated normal faults originally formed by middle Miocene extensional tectonics. Despite very slow (less than 0.1 mm/yr) late Quaternary slip rates, our work suggests the presence of prev, iously unrecognized faults that pose more seismic hazards to Tokyoand urges more intense efforts to shed more light on the recent slip rates, magnitude and recurrence of the past earthquakes on them.