Earth Planets Space, Vol. 60 (No. 10), pp. 1029-1034, 2008LETTER
Independent Administrative Institution, Port and Airport Research Institute, 3-1-1 Nagase, Yokosuka 239-0826, Japan
(Received June 22, 2007; Revised November 27, 2007; Accepted December 5, 2007; Online published November 7, 2008)
A waveform inversion study was conducted to reveal the rupture process of the 2007 Noto Hanto, Japan, earthquake using near-source strong ground motion records. To avoid uncertainty in the subsurface structure in and around the source region when calculating Green's functions, I used the aftershock records as empirical Green's functions. To ensure that the path and the site effects are shared between the ground motions from the mainshock and those from aftershocks, the mainshock fault plane was divided into four domains, each of which was allocated to one of the aftershocks used as the empirical Green's function events. The result of the inversion indicated that the rupture process included the break of two asperities. The first asperity, located close to the JMA hypocenter, was broken soon after the rupture started. This was followed by an extension of the rupture and the subsequent break of the second shallow asperity. The total moment of the mainshock was estimated to be 1.96E+19 N m, which is roughly consistent with the moment estimated by the F-net (1.36E+19 N m). Agreement between the observed and synthetic ground motions is quite satisfactory.
Key words: The 2007 Noto Hanto earthquake, rupture process, empirical Green's function.