Earth Planets Space, Vol. 60 (No. 2), pp. 89-94, 2008LETTER
Susumu Kurahashi1, Kazuaki Masaki2, and Kojiro Irikura3
1Graduate School of Engineering, Aichi Institute of Technology
2Faculty of Engineering, Aichi Institute of Technology
3Disaster Prevention Research Center, Aichi Institute of Technology
(Received July 2, 2007; Revised November 13, 2007; Accepted November 22, 2007; Online published February 19, 2008)
A source model for estimating broad-band ground motions from the 2007 Noto-Hanto earthquake (Mw 6.7) is estimated from a comparison of the observed records of the mainshock and synthesized motions based on the characterized asperity model using the empirical Green's function method. The observed records of aftershocks used as the empirical Green's functions are carefully selected to have almost the same radiation characteristics and source distance as the asperities of the mainshock. The best-fit source model consists of two asperities of different size. A large one is located just above the hypocenter, with an area of 6.3×6.3 km2 and stress drop of about 26 MPa. A smaller one is located north-east of the large one, with an area of 3.6×3.6 km2 and stress drop of about 10 MPa. The stress drop of the large one is about twofold higher than the average values of inland crustal earthquakes so far estimated, while that of smaller one is almost average. We found that the remarkable directivity pulses from the source model struck the northern part of the Noto peninsula, causing heavy damage in some towns there.
Key words: Broad-band strong ground motion, empirical Green's function method, 2007 Noto-Hanto earthquake, selection of aftershock records as EGF, source model.