HR: 08:00h
AN: S41D-01 INVITED    [Abstracts]
TI: An over view of ground-based electromagnetic observations addressed to seismo- electromagnetism in Japan
AU: * Nagao, T
EM: nagao@scc.u-tokai.ac.jp
AF: Earthquake Prediction Research Center, Orido 3-20-1, Shimizu, Shizuoka, 424-8610, Japan
AB: Almost all through the human history, electromagnetic (EM) phenomena associated with earthquakes (EQ) have been repeatedly reported. Especially 1995 Kobe earthquake brought a great impact to the earthquake prediction studies in Japan. After this devastating event, Science and Technology Agency (STA) decided to initiate five year programs of Earthquake Frontier Program which included RIKEN/NASDAfs subprograms. Both subprograms addressed to the short-term earthquake prediction research by using the electromagnetic methods, and the main objective was to attain comprehensive understanding of the pre-, co- and post seismic EM phenomena related to EQs. Both projects produced many appraisable results. However, there is still a long way to go, physics of DC to ULF/ELF signal generation/transmission and so on. We now consider that EQ related EM signals may be classified into two major groups. One is EM signals supposedly emitted from the focal zone and the other is anomalous transmission of EM waves over the epicentral region. Of-course, to establish the science of seismo-EM phenomena, we need continued efforts to collect and accumulate more data on one hand and to advance basic physics on the other. In the presentation, we briefly summarize the current status of ground-based EM measurements from ULF to VHF ranges in Japan (DC-ULF geoelectric potential difference, ULF, ELF and VLF three-component magnetic, VLF, LF and VHF anomalous transmission of radio waves, etc.) and propose the future direction (tactics) of EQ- related EM study in Japan.
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting