HR: 0830h
AN: S21D-0335    [PDF]
TI: Hypocenter Determination To Issue The Earthquake And Tsunami Information From LISS And JISNET Data By Using the Grid-Search Method
AU: * Kanjo, K
EM: kkanjo@met.kishou.go.jp
AF: Matsushiro Seismological Observatory, JMA, Matsushiro, Nagano, 381-1232 Japan
AU: Furudate, T
EM: tfurudate@met.kishou.go.jp
AF: Matsushiro Seismological Observatory, JMA, Matsushiro, Nagano, 381-1232 Japan
AU: Ohtaki, T
EM: t-ohtaki@aist.go.jp
AF: Geological Survey of Japan, AIST, Central 7, Tsukuba, 305-8567 Japan
AU: Inoue, H
EM: inoue@bosai.go.jp
AF: National Research Institute for Eaarth Science and Disaster Prevention, Ten'nohdai, Tsukuba, 305-0006 Japan
AU: Sawada, M
EM: sawada@vsi.esdm.go.id
AF: Japan International Cooperation Agency, Yoyogi, Tokyo, 151-8558 Japan
AU: Purwana, I
EM: ibnu@bmg.go.id
AF: Bureau of Meteorology and Geophysics, Kemayoran, Jakarta, 10720 Indonesia
AB: Matsushiro Seismological Observatory, Japan Meteorological Agency developed the real-time conversation processing system for the improvement in hypocenter determination accuracy and speeding up of a far coast tsunami earthquake by using the data of LISS (Live Internet Seismic Server),USGS. The processing displays a waveform as real time at the time of the occurrence of an earthquake, it can perform time-axis expansion, expansion and reduction of an amplitude axis, rearrangement of a channel, comparison with the theoretical travel time, and the phase detection etc. . The grid-search method for having devised for calculation time shortening is used for hypocenter calculation. In the first calculation, the latitude and longitude are fixed to an interval 5 degrees, focal depth is fixed to 30km and the origin time is fixed to an interval of 60 seconds. Next, the search range and a grid interval are made small covering 17 stages, finally, 0.01 degrees hypocenter accuracy search for latitude and longitude, 1 km for the depth searches and 0.1 second for the origin time. The process time is required about 5 seconds, using a personal computer in calculation. The hypocenters are determined within the limits of few 10km in general as compared with the hypocenters of USGS. Next, we applied this technique to the JISNET(Japan and Indonesia broad-band seismometer network) data installed in Indonesia, in order to investigate an earth internal structure, and we evaluated the hypocenter determination accuracy about the event generated in and around the Indonesia of it about the earthquake beyond M6.5 considered to be necessity for a big earthquake or a tsunami information announcement, it turns out that the hypocenter information is searched for in sufficient accuracy. However, the data using satellite communication etc. needs to be real-time for the utilization. In this case, a total of 23 JISNET stations and at least eight points of the optimal arrangement are enough. If the extensive real-time data will be sent to LISS of USGS, the hypocenter determination accuracy using these data will improve if the extensive real-time data will be sent to LISS of USGS, and it will lead not only to this region but to improvement for the far coast tsunami information in the Pacific rim. In near future, we will develop the automatic hypocenter determination system from the high sensitivity seismic array real-time data in Japan by using this technique.
DE: 7299 General or miscellaneous
SC: Seismology [S]
MN: 2003 Fall Meeting