IISEE’s CMTs, Aftershock Distributions, Fault planes, and Rupture processes for recent large earthquakes in the world [Japanese version]

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[Outline]

The IISEE has started a project to determine the following earthquake information for recent large (Mw7.2) earthquakes in the world by the analytical techniques developed by the IISEE staff members and visiting researchers.

n  Centroid moment tensor

Centroid moment tensors are determined analyzing long period body wave data recorded at GSN (Global Seismological Network) stations.

u  Period: 1994 – October 2010

u  Analytical method: Grid search approach by Hara (2004, 2005)

u  Principal Investigator: Tatsuhiko Hara (IISEE. E-mail: thara at kenken.go.jp)

n  Aftershock distribution and corresponding fault plane

Aftershocks including mainshock and foreshocks are relocated using P-wave arrivals from International Seismological Centre (ISC) CD-ROMs. Then, the corresponding fault plane is determined based on the obtained aftershock distribution (nodal planes are taken from the Global CMT catalog).

u  Period: January 1994 – 2007

u  Analytical method: The modified joint hypocenter determination method (MJHD. Hurukawa and Imoto, 1992; Hurukawa, 1995; Hurukawa et al., 2008)

u  Principal Investigator: Nobuo Hurukawa (IISEE. E-mail: hurukawa at kenken.go.jp)

n  Rupture process

Earthquake rupture processes are determined analyzing broadband waveform data recorded at GSN (Global Seismological Network) stations. The above aftershock analyses are referred to set up earthquake fault planes.

u  Period: January 1994 – November 2007

u  Analytical method: Waveform inversion considering covariance components in inversion analyses of densely sampled observed data by Yagi and Fukahata (2008)

u  Principal Investigator: Yuji Yagi (Tsukuba University/ IISEE visiting researcher. E-mail: yagi-y at geol.tsukuba.ac.jp)

 

  We analyzed large (M7) events that occurred between 1976 and 2007 to determine their aftershock distributions and corresponding fault planes to expand the database (under adjustment. Thank you for your patience).

IISEE’s aftershock distributions and corresponding fault planes

  We have developed software to perform strong ground motion simulation for seismic bedrock using stochastic Green’s function method.

  We provide a set of earthquake fault parameters used in tsunami simulations that are presented on the IISEE web site.

  We found azimuthal dependence of high frequency energy radiation for the 2011 Off the Pacific Coast of Tohoku earthquake.


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