The evolution characteristics of positive and negative earthquakes before strong quakes in Kanto area and the Hyugo earthquake in Japan

Abstract

This paper studies the evolution characteristics of positive and negative quakes before Hyugo earthquake ofM=7.2 and several strong quakes in Kanto area in Japan. The results show that the earthquakes over a certain magnitude are mainly positive ones a certain time before the main shock in or near the focal regions of most strong quakes, and form a concentrating intervals of positive quakes. The main quakes generally locate in or near the areas of positive quake distribution. Negative quakes often occur several months before the main shocks (not excluding positive ones), with the decrease of LURR (Loading / Unloading Response Ratio) values. It possibly shows that earthquake-generating process has come to a short-term stage. These characteristics may help to predict the time and location of the future earthquakes, and have been applied to the preliminary prediction of the time and the location of the earthquake ofM=6.6 on Sep. 11, 1996 in Kanto area.