| 摘 要： | A Ms 6.2 strong earthquake occurred at 16:07 on October 20,1990 in a juncture of the three counties of Jingtai,Tianzhu,Gulang in Gansu Province.Field observations indicate that the macroseismic epicenter lies from Xiatang to Daquanwan and that its geographical location is at 37°07'N and 103°37.5'E.The epicentral intensity is Ⅷ degree.The meizoseismal region,covering about 20 km-,is an elliptical area with its long axis orienting NWW.In the circled areas with the earthquake intensity from VI to Ⅷ degree,the formation cause of high intensity(Ⅷ)anomalous area appeared in the Ⅶ area has been discussed in this paper.According to the data of direct aftershock area,epicentrai intensity area,focal mechanism solution and the direction of the ground motion,etc.,this strong earthquake was caused by latest sinistral lateral movement of Laohushan fault that has been the most active fault since the Holocene.
|
