A seismic event on August 20, 1983: double explosion or a single earthquake |
| |
Authors: | S K Arora T K Basu |
| |
Institution: | Seismology Section, Bhabha Atomic Research Centre, Trombay, Bombay - 400 085, India |
| |
Abstract: | An interesting weak seismic event occurred on August 20, 1983 in the Caspian Sea region in southwestern U.S.S.R., which produced at Gauribidanur array two distinct seismic signals, viz. the leading P signal and a similar signal after an interval of nearly 12 s. Preliminary data corresponding to these two signals led to an initial assumption that the event was a double underground nuclear explosion. However, the focal depth of this event from P arrival-time data of 21 stations was found to be 45 km. Further processing of the Gauribidanur array seismograms confirmed that the second signal, detected exactly 11.85 s after the first arrival, was none other than the surface-reflected P pulse which lent excellent support to the source depth estimate. By using three discriminants, viz. signal complexity, third moment of frequency and relative efficiency of generation of core-reflected P, the event was objectively compared with 10 small presumed underground nuclear explosions in southwestern U.S.S.R. to conclude that the August 20, 1983 event was a shallow-focus small earthquake in the Caspian Sea area. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|