1590年7月7日甘肃永靖东南地震考证

公元1590年7月,在甘肃临洮附近有破坏性历史地震记载"……坏城廓庐舍,压死人畜无算"。同月,青海东部的冰沟城(今乐都县东北)也因地震而城崩。在过去出版的地震目录中,均按两次地震列出,分别称为甘肃临洮51/2级地震,震中烈度Ⅶ度;青海乐都5级地震,震中烈度Ⅵ度。根据史料考证和现场调查结果,综合分析认为,上述两次地震很有可能为同一次地震,其震中位于甘肃永靖东南的马衔山区,震中烈度达Ⅷ—Ⅸ度,震级61/2级左右,其发震构造很可能为兰州马衔山北缘断裂带的中西段。

Textual Research on July 7,1590 A.D.Yongjing Earthquake in Gansu Province

According to the historical data record,on July of 1590 A.D.,there was a destroyed earthquake occurring near Lintao county city of Gausu Province,which caused"......the town and city destroyed,houses damaged,persons and domestic animals died countless".In the same month,the Binggou town located at east of Qinghai Province,now at the northeastern of Ledu county city,also damaged by the earthquake.These records were believed to be the results of two different earthquake events in the old published earthquake catalogues.For the first one the magnitude is 5 1/2 in Lintao of Gansu Province,the central intensity is about 7.For the second one the magnitude is 5 in Ledu of Qinghal Province,the central intensity is about 6,respectively.Based on the recent textural research and field investigation,we found that these two moderate earthquakes are very likely to be one strong earthquake event.The epicenter area of this earthquake locates at the mountain area in southeast of Yongjing county city,with the epicenter intensity of about 8-9,and the magnitude of 6 1/2.This earthquake may be possibly the result from new faulting activity along the middle or west segment of the northern margin of Maxianshan Mt active fault zone.