Local Time Statistical Character and Frequency Spectrum Analysis Based on ISC,SCSN and CRN Seismological Catalogues
FENG Xiang-Dong 1,2 WEI Dong-Ping1(1 Laboratory of Computational Geodynamics, Graduate school of the Chinese Academy of Sciences, Beijing 100049, China;2 Earthquake Administration of Hebei Province,Shijiazhuang 050021,China)
The ISC, SCSN and CRN seismic catalogue data are first transformed to the local time system and the sequence statistics are made, the time-occurring number of earthquakes are set up on the system of local time, and then the frequency spectrum analysis on the earthquake sequence is done to pick up information related to the characteristic period. The results indicate: (1) time-occurring number of earthquake is up to the maximum value at local time 0:00 AM and 1:00 PM while down to the minimum at local time 9:00 AM and 7:00 PM; (2) there are two typical periods of 12h and 24h; (3) The small earthquakes and large earthquakes are different in spatial and temporal distributions. The results of frequency spectrum analyses show that there are not only periods of 12h and 24h connected with the diurnal tide and the semidiurnal tide, respectively, but also the periods of 11.7a, 1a, and 17.5a connected with 11-year sunspot cycle, earth revolution, and nearly to ascending node tropical year of the moon, respectively.