Portal de Periódicos da CAPES

Earthquake Prediction Program in Japan

2011; American Geophysical Union; Linguagem: Inglês

10.1029/me004p0635

2329-0307

Kiyoo Mogi,

Seismology and Earthquake Studies

During the last few years, several destructive earthquakes including the 1974 Izu-hanto-oki (M 6.9), the 1978 Izu-Oshima-kinkai (M 7.0) and the 1978 Miyagi-oki (near Sendai)(M 7.4) earthquakes occurred successively in Japan. In spite of the recently intensified observations, reliable precursor data are very limited, because the density of the observation network is still insufficient for predicting earthquakes of magnitude ∼7. Before the Izu-Oshima-kinkai earthquake, various observations had been intensified in the Izu Peninsula; microearthquake swarms and anomalous crustal uplift in the Izu Peninsula were observed about two years before the earthquake. Several kinds of remarkable precursory phenomena were observed here, but the Izu-Oshima-kinkai earthquake was not predicted. In the Izu Peninsula, we still have no real-time data processing system for various observations related to earthquakes of magnitude ∼7. The Yamasaki fault in the Kinki district in western Japan has been investigated as a test field for earthquakes of magnitude ∼4–5. Some earthquakes along this fault were forecast on the basis of the regularity in seismic activity and the observations of various kinds of precursors in this region. On the basis of the recurrence time of historical, large earthquakes along the Nankai trough and the crustal deformation observed by geodetic surveys, the Tokai region has been indicated as a potential region for a great shallow earthquake of magnitude ∼8 since 1969. For the purpose of predicting this potentially large earthquake, a dense network of observation instruments has been set up in the Tokai region. The various data are telemetered to the center of the Japan Meteorological Agency (JMA) in Tokyo. When anomalous behaviour is noted, the Earthquake Prediction Council evaluates the data and conveys their findings to the director general of JMA. The characteristics of precursory earthquake phenomena in Japan are compared with those in different tectonic regions, such as central California and some regions in China.