Advance short-term prediction of the large Tokachi-oki earthquake, September 25, 2003, M= 8.1 A case history

Abstract

Tokachi-oki earthquake in northern Japan, September 25, 2003, magnitude 8.1, was predicted six months in advance by a short-term earthquake precursor "chain" that reflects an increase of the correlation range among small earthquakes. This prediction is part of the ongoing test of a new short-term prediction method; the test covers territories of Japan, California, and Eastern Mediterranean. Qualitatively, precursory chain is a dense sequence of small earthquakes that had quickly extended over a long distance. A strong earthquake is expected within nine months after such chain is formed, in its formally defined vicinity. Chains are analyzed in conjunction with intermediate-term precursors, emerging with characteristic lead time of years. Methodology of prediction is named "Reverse Tracing of Precursors" (RTP), since precursors are considered in the reverse order of their appearance. That allows detecting short-term precursors not detectable with direct order of analysis. RTP was tested retrospectively for California, Japan, and Eastern Mediterranean, where 22 more strong earthquakes occurred during the time considered. The concept underlying RTP is interaction of lithosphere dynamics on different temporal scales. The described results enhance our fundamental understanding of lithosphere dynamics and, on the practical side, our capability for earthquakes preparedness. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.