[J09-6] Geodesy and seismology general contributions VI

[J09-6-02] Geodetic and Seismological Risk of Operation of Nuclear Power Plants in Japan

^○Shuzo Takemoto (Kyoto University, Kyoto, Japan)

The national project of earthquake prediction started on 1965 in Japan. Most prospective approach for short term predictions was considered to be continuous monitoring of crustal deformations. This idea was based on observational results of Sassa and Nishimura (Kyoto University). They first reported that anomalous tilt change with the order of 0.1" was observed at the Ikuno mine located 60km away from the epicenter of the 1943 Tottori eq. of M7.2. Since then, reliable anomalous tilt or strain changes were not reported. Destructive earthquake of M7.3 occurred around Kobe city on 17 January 1995. Using a precise laser strainmeter, we had been carried out strain measurement at the Rokko-Takao station in Kobe. The station was existing just above the fault plane of the earthquake. We could not find any anomalous strain changes before the earthquake. This fact indicates that precise observations using tiltmeters and strainmeters are not effective tools for short term predictions of earthquakes. It is abnormal worldwide that more than 50 nuclear power plant units were installed in Japan. The Fukushima 1st nuclear plant suffered catastrophic damage due to the 2011 off the Pacific coast of Tohoku Eq. (Mw9.0). It is estimated that about 1% of total radioactive substances were released into the atmosphere during one week from March 11, 2011, and 99% of radioactive substances are remaining in the vessels of reactors as the form of nuclear fuel debris. In near future, we must consider the possibility of the outbreak of the earthquake that Fukushima will be shaken by strength of seismic intensity of 7 or 6. We must consider the Geodetic and Seismological Risk of Operation of Nuclear Power Plants, not only the Fukushima 1st Nuclear Power Station but also all Nuclear Power Stations in Japan.