Source parameters of the 2007 Noto Hanto earthquake sequence derived from strong motion records at temporary and permanent stations

Abstract

A large crustal earthquake, the 2007 Noto Hanto earthquake, occurred west off the Noto peninsula in Ishikawa prefecture, Japan, on March 25, 2007. We started temporary strong motion observation at five sites within the aftershock area from about 13 h after the main shock occurrence. We first applied the spectral inversion method to S-wave strong ground motion records at the temporary and permanent stations. We obtained source specta of the main shock and aftershocks, Q s (quality factor for S-wave) values (Q s = 34.5 f 0.95 ) and site responses at 22 sites. We then estimated a source model of the main shock using the empirical Green's function method. The source model consists of three strong motion generation areas and well explains the observed records. Finally, we examined the consistency of the main-shock source models estimated from the above two analyses. The high-frequency level of the acceleration source spectrum based on the main-shock source model is consistent with the source spectrum estimated from the spectral inversion. The combined area of strong motion generation areas is approximately half of the value expected by the empirical relationship, and the high-frequency level of acceleration source spectrum is approximately 2.5 times larger than the empirical relationship for shallow inland and inter-plate earthquakes.

Source-Rupture Process of the 2007 Noto Hanto, Japan, Earthquake Estimated by the Joint Inversion of Strong Motion and GPS Data

“…The heterogeneous slip models of the 2007 Noto Hanto earthquake have been derived also in other studies by combined use of synthetic aperture interferometry (InSAR) and GPS data (Fukushima et al, 2008;Ozawa et al, 2008), strong-motion data (Aoi and Sekiguchi, 2007;Horikawa, 2008;Wu and Horiuchi, 2008), and combined use of strongmotion and GPS data (Momiyama et al, 2009). The source models based on empirical Green's function methods are also proposed (Kurahashi et al, 2008;Maeda et al, 2008;Nozu, 2008;Shiba, 2008). Most of these studies found a large asperity in the vicinity of the hypocenter, which is consistent with our result.…”

Relation Between Stress Drops and Depths of Strong Motion Generation Areas Based on Previous Broadband Source Models for Crustal Earthquakes in Japan

“…The number of SMGAs of each earthquake is one to three except for five by Hirai et al [16]. The stress drops are less than 30 MPa except for those for the 2007 Noto Hanto earthquake estimated by Maeda et al [27]. Although source models for the same earthquake are different among researchers, large SMGAs tend to be located at deep places.…”

“…6.1. A total of 22 articles on SMGAs [1,6,13,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] for 13 crustal earthquakes of the moment magnitude Mw from 5.7 to 6.9 in 1995 to 2011 are used. The numbers of the strikeslip, reverse, and normal faults are six, six, and one, respectively.…”