DISTRIBUTION OF LOCAL MEAN LUNAR TIMES OF SIGNIFICANT SHOCKS IN SOURCE REGION AND ITS VICINITY BEFORE LARGE EARHQUAKE AND ITS EXPLANATION
CHEN RONG-HUA; DING XIANG(Center for Analysis and Prediction. SSB, Beijing 100036, China)
The distribution of local mean lunar time t of significant shocks happened in source region and its vicinity before a large earthquake is studied in this paper.12 earthquakes with Ms7 and 44 earthquakes with Ms 6 are studied in this paper. The tidal generation force arisen by the moon is a cyclic function or abut 12 hour 25 minute in the main and the two tidal generation forces anywhere in the earth arising by the moon are equal in general when the moon lies to the two sites of 180°interval of local moon lunar time. Based on this phenomenon the crossing angle △τA between local mean lunar time of two significant shock before a large earthquake and the mean vale △τB of the crossing angles between the local mean lunar time of two singificant shocks and the main earthquake are calculated in this paper.The calculated results show that in regard to most earthquakes the value △τA and △τB are less than or equdl to 45°, and which clear up that the moon locates at abut same azimuth of the source region or the vicinity of 180°from the azimuth when significant shocks and the main earthquake happened. The results are explained by IPE model of earthquake preparation in this paper, and it is possible that the distribution of the local mean lunar time of the significant shocks and the main earthquake is relative with the fault trend of main earthquake. The paper point out that the phenomenon of △τA≤45°may be a earthquake precursor and applied to earthquake prediction.