ESTIMATION OF STRONG GROUND MOTIONS IN MEIZOSEISMAL REGION OF THE 1976 TANGSHAN, CHINA, EARTHQUAKE

The 1976 Tangshan, China, earthquake of M(s) 7.8 killed 242,000 persons, seriously injured 164,000 persons, and caused direct property losses totaling 8 billion Yuan Ren Min Bi (US $4.3 billion). Few investigations have been performed to estimate the characteristics of the strong ground motions in the meizoseismal region of this earthquake using either seismological or earthquake engineering approaches. In this paper, the observed far-field accelerograms of the mainshock are simulated by using the records of the second largest aftershock of M(s) 6.9 as Green's functions in order to obtain appropriate fault models for the mainshock. The strong ground motions in the meizoseismal region of the mainshock are then estimated by using these fault models and the records of several aftershocks with a magnitude of about 5 which were observed at temporary stations in the damaged area. The results indicate that large horizontal acceleration responses over 1000 cm/sec(2) and vertical acceleration responses over 2000 cm/sec(2) acted on the structures with natural periods shorter than 0.1 sec in the wide meizoseismal region having a length of 90 km.