SOME PREMONITORY PHENOMENA OF THE 1995 HYOGO-KEN NANBU (KOBE) EARTHQUAKE: SEISMICITY, B-VALUE AND FRACTAL DIMENSION

Abstract

This paper presents a detailed and complex analyses of the spatio-temporal evolution of seismic activity between 1976 and 1998, in a broad area surrounding the epicentre of the 1995 Hyogo-ken Nanbu (Kobe) earthquake as well as in the source area. Various precursory changes in seismicity, such as quiescence followed by increased seismic activity, b-value and fractal dimension (correlation dimension, D2) anomalies appear approximately two years before the occurrence of the major event. An increased level of background seismicity is clearly observed after the occurrence of the Kobe earthquake, particularly in the northeast extension of the source area. All these 'anomalous' changes in seismic activity before and after the occurrence of the 1995 Hyogo-ken Nanbu earthquake appear in a relatively large region surrounding the epicentre of the main shock as well as in the source area.