P AND S TRAVEL TIMES FROM EARTHQUAKES IN THE CHINESE REGION

In this work, we collected the observed data of 266 earthquakes occurred in China and its bordering region during the years 1952-1971. A total of some 20,000 arrivals of P and S waves were available from more than 500 seismological stations at home or abroad. In order to reduce the travel time data of all earthquake focal depths to that of surface foci, and to strip the earth's crust, a 2-layer average velocity model of the crust for the region was proposed based on observations of large explosions and results of some other studies of crustal structure, combined with the above mentioned data of seismological observations. All of the earthquake epicenters and origin times have been revised by an iteration procedure. The smoothing technique of cubic splines as described by Curtis (1970) was applied for the P and S travel times for surface foci. The Herglotz-Wiechert-Bateman method was used to inverse P and S velocity distribution with depths in the mantle for this region. Finally, a set of travel times tables of P and S waves for various focal depths were constructed in the epicentral distance range of △= 0-104. Practical experiences show that the new tables have been relatively improved in accuracy for epicentral location of earthquakes of this region than other tables.