Regional Seismic Database For Southwest China

Abstract : We have built a database of high-quality 3-component digital broadband and short-period recordings from 23 stations of a regional digital seismic network in southwestern China. There are frequent natural earthquakes and man-made seismic activities in the region, which provides an immense amount of data for regional seismic studies. The database contains mainly the regional digital broadband waveform data recorded at the newly implemented regional digital seismic network. Each seismic station in this network has digital broadband seismographs and short-period seismographs with 16-bit A/D converters, as well as data processing and transfer facilities. The bandwidth of the digital broadband seismograph is about 20 sec - 25 Hz. The major specifications of the instrument are: (1) sensitivity of 1~2x10(exp -8)m.s(exp -1)/LSB; (2) dynamic range greater than 90dB, (resolution equal to or greater than 2(exp -15) for 16 bit); (3) linearity greater than |10 (exp -3)|; (4) time error less than 1 ms. The center of the regional digital seismic network has the function of seismic data collection, storage, processing and maintenance. This study will report on the seismic characteristics of regional phases in the region. Multimax has obtained and examined the digital waveform data for over 900 seismic events recorded by the regional digital seismic network. We also performed detailed time- and frequency-domain analyses of local and regional signals detected from events for which some ground-truth information about the seismic sources may be known. Our preliminary analyses of the waveforms have shown that such data provide insights to the studies of the excitation and propagation of regional phases in the region. These studies include seismic event locations, Pg/Lg spectral ratio, coda attenuation, identification, and regional structure model from tomographic inversion.