HR: 17:20h
AN: S24B-05    [Abstracts]
TI: Estimating the Fault Rupture Geometry in Real Time for the 2007 Noto Hanto and 2007 Niigata-ken Chuetsu-oki Earthquakes
AU: * Yamada, M
EM: masumi@eqh.dpri.kyoto-u.ac.jp
AF: Kyoto University, Gokasyo, Uji, 611-0011, Japan
AB: In October 2007, the Japan Meteorological Agency starts providing earthquake early warning publicly. They broadcast the early warning message on TV and radio in real time, so that public people can take damage- mitigating actions before strong shaking arrives. The research topic of earthquake early warning attracts public people as well as seismologists and engineers. Japan had two major earthquakes in 2007 which caused significant damage on buildings and infrastructures. The 2007 Noto Hanto earthquake (Mw6.7) occurred on March 25 at off Noto peninsula near west coast of this peninsula. After 4 months, July 16, the 2007 Niigata-ken Chuetsu-oki earthquake (Mw6.7) hit near the west coast of Honshu Island, which killed 11 people. This research applies earthquake early warning algorithms to the dataset of these earthquakes. We applied two different approaches to determine the ongoing fault rupture geometry from accelerograms. Based on these methods, the current direction of the fault trace the current fault rupture length, and the current fault extent can be estimated. The near-source/far-source discriminant function can tell the probability that the station is located in the near- source region based on the amplitude of vertical acceleration and horizontal velocity. The estimation of near- source station agreed with fault model very well. Stations on the fault model have high probability that the station is near-source. The real-time rupture geometry estimation agrees with the actual earthquake rupture geometry quite well. For the Noto Hanto earthquake dataset, the rupture direction can be estimated 12 seconds after the event onset and the final solution is achieved after 15 seconds. The rupture estimate for the Niigata-ken Chuetsu-oki earthquake dataset is more difficult to converge since the station distribution is limited in one side of the fault. These methodologies to characterize rupture geometry in real time were originally designed for larger earthquakes with larger rupture dimensions, but it is shown that they also work well for the size of these earthquakes (Mw 6.7).
DE: 1734 Seismology
SC: Seismology [S]
MN: 2007 Fall Meeting