Digital near source accelerograms recorded by instrumental arrays in Tangshan, China. Part I (1982.7-1984.12)

Abstract

The ultimate goal of earthquake hazard mitigation research is to gain sufficient understanding of the phenomena involved in an earthquake to minimize the loss of life and property resulting from such an event. In order to design safe, economical structures and facilities in seismic areas, it is necessary to understand the nature of the ground motion generated by an earthquake. This understanding can ultimately come only from the measurement of the strong ground motion resulting from actual damaging earthquakes. In order to facilitate the acquisition of strong ground motion data world-wide, an International Workshop on Strong Motion Earthquake Instrument Arrays was held in 1978 in Hawaii. Participants in the Workshop appealed to the earthquake-threatened countries of the world to undertake a concerted effort to establish strong-motion accelerograph arrays and networks. In response to the appeal of these experts in earthquake hazard mitigation, and in accord with the "China-U.S. Protocol for Scientific and Technical Cooperation in Earthquake Studies," a joint research project on strong ground motion measurement has been established in China. In the first phase of this project, from April 1981 to December 1984, 22 Kinemetrics PDR-1 Digital Event Recorders equipped with FBA-13 Force Balance Accelerometers, and 18 Kinemetrics SMA-1 Analog Accelerographs were deployed in China. Of this total, 13 PDR-1 and 3 SMA1 instruments were deployed in a surface array and a three-dimensional array in the aftershock region of the 1976 Tangshan earthquake. These two arrays recorded a total of 1053 near-source accelerograms from 416 earthquakes with magnitudes ranging from ML = 1.2 to 5.7. The source-station distances ranged from 2 to 45 kilometers. Most of the records contain the complete P- and S-wave motion along with accurate absolute time. Both the volume and quality of the accelerograms are much greater than ever before obtained in China. The largest event recorded was the ML = 5.7 Lulong earthquake of October 19, 1982. Nine instruments were triggered by this event. The epicentral distance from the recording stations ranged from 5 to 41 kilometers, and the corresponding peak horizontal acceleration ranged from 0.217 to 0.008g. Accelerograms were recorded by the three-dimensional array from twenty-eight events. Measurements were made to a depth of 900 meters below the ground surface. The records obtained provide a unique source of data for the study of the propagation of seismic waves near the earth's surface. In order to make these data more useful, they will be published along with site data in a separate volume. In this report, 218 of the most significant accelerograms; are published. The data was obtained from earthquakes with magnitudes ranging from ML = 2.3 to 5.7. All of the data reproduced in this report is available on 9-track computer tape.