Reverse tracing of short-term earthquake precursors

We introduce a new approach to short-term earthquake prediction named “Reverse Tracing of Precursors” (RTP), since it considers precursors in reverse order of their appearance. First, we detect the “candidates” for the short-term precursors; in our case, these are newly introduced chains of earthquakes reflecting the rise of an earthquake correlation range. Then we consider each chain, one by one, checking whether it was preceded by an intermediate-term precursor in its vicinity. If yes, we regard this chain as a precursor; in prediction it would start a short-term alarm. The chain indicates the narrow area of possibly complex shape, where an intermediate-term precursor should be looked for. This makes possible to detect precursors undetectable by the direct analysis. n best be described on an example of its application; we describe retrospective prediction of two prominent Californian earthquakes—Landers (1992), M=7.6, and Hector Mine (1999), M=7.3, and suggest a hypothetical prediction algorithm. This paper descripes the RTP methodology, which has potentially important applications to many other data and to prediction of other critical phenomena besides earthquakes. In particular, it might vindicate some short-term precursors, previously rejected as giving too many false alarms. tion of the algorithm per se requires its application in different regions with a substantial number of strong earthquakes. First (and positive) retrospective results are obtained for 21 more strong earthquakes in California (M≥6.4), Japan (M≥7.0) and the Eastern Mediterranean (M≥6.5); these results are described elsewhere. The final validation requires, as always, prediction in advance for which this study sets up a base. We have the first case of a precursory chain reported in advance of a subsequent strong earthquake (Tokachi-oki, Japan, 25 September 2003, M=8.1). le mechanisms underlying RTP are outlined.