山崎断層東部における微小地震の広ダイナミックレンジ・三点観測

Abstract

At the east end of the Yamasaki fault, tripartite observation of microearthquakes was ope-rated with wide dynamic range recording system. Results of the analysis are as follows.On the structure and epicenter locations around tripartite stations;1) Fairly low velocity surface layer must exist in the upper crust.2) Epicenter locations determined by Tottori Microearthquake Observatory have the sys-tematic erorr of about 2 km in southeast direction.On characteristics for Kasai earthquake sequence;3) There exist lower limit of initial pulse width of P-wave (M<1), peak in magnitude-frequency distribution (1.5<M<2.) and multiple fracturing (M=2.9), the same as other earth-quake sequences.4) Effective stress acting on a fault plane increases with magnitude for -1<M<2, andhave the same value for 2<M<2.9.