Abstract: Study of historical earthquake is one of the important methods to understand the seismic activities and analyze the seismogenic faults. On the May 25^th, 1568 AD, a destructive earthquake occurred to the northeast of the present-day city of Xi'an, Shaanxi Province. Because this earthquake happened shortly after the 1556 M8 earthquake and was regarded as an aftershock, it has received little attention in previous studies. Previous earthquake catalogue agreed in assigning a magnitude 6 3/4 to this earthquake but had different epicentral locations and seismic intensity, and the seismogenic structure remains ambiguous.
Based on textual research of historical earthquake and field investigation, the Jingyang County, Gaoling County, and Xianning County, were the worst hit area by the earthquake, and the areas, including Yongle Town, Gaozhuang Town at southeastern Jingyang County to Gaoling County and its southeastern present-day Jijia and Zhangbu, should be the mesoseismal area of this earthquake. The epicenter intensity of this earthquake is Ⅸ⁺(9~10 degrees), and the magnitude is estimated to be 7. The isoseismal lines were drawn to exhibit the various intensities of the areas damaged during the event, with its major axis directed NWW. Intensities reached Ⅸ⁺ in the zone extending west-northwest parallel to the Weinan-Jingyang Fault. This fault, characterized by a normal fault that developed during the Cenozoic extensional history of the Weihe Basin, dipping to the north at an angle of 60°~80°, is one part of the southern boundary faults in Weihe graben. There are geomorphological and geological evidences of recent activity of the fault during (180±30)a BP to (1 600±30)a BP. At T₁-T₂ fluvial terraces on the north bank of Weihe River, the scarps were faulted during Ming Dynasty, and sandy soil liquefaction, dense structural tensional fissures and faulted strata are noted in stratigraphic profiles and trenches. Thus, we suggest that this fault can reliably be regarded as being active during Holocene, and re-name the earthquake as the Shaanxi Gaoling earthquake.

Key words: 1568 Shaanxi Gaoling earthquake, textual research of historical earthquake, seismogenic structure, Weinan-Jingyang Fault

摘要： 研究历史地震事件是认识地震活动规律、分析发震构造的重要途径之一。1568年5月25日（隆庆二年四月十九日申时），在西安东北高陵地区发生一次强烈地震，造成各类建筑物倒塌毁坏"尽如平地"，"人畜伤亡甚众"。此前的地震目录将这次地震命名为陕西西安东北地震，震级为6 3/4级，极震区烈度为Ⅸ。文中通过对历史地震资料的再考证及野外调查，认为该次地震的极震区位于在泾河以北的泾阳县东南的永乐镇、高庄镇北部至高陵县及其东南姬家乡、张卜乡一带，并命名为陕西高陵地震，烈度为Ⅸ⁺（Ⅸ~Ⅹ）度，估算其震级可达7级。同时，对震害进行了细致分析并重绘制了该地震的等震线图，得到其极震区的位置，同时发现其等震线长轴为NWW向，与渭南-泾阳断裂相吻合。该断裂为全新世活动正断层，沿断裂地貌保留了部分断错阶地陡坎，断层剖面中可见砂土液化、张性构造裂缝等新活动遗迹，最晚活动时间为（180±30） aBP至（1 600±30） a BP之间。文中分析认为1568年陕西高陵7级地震的发震构造为渭南-泾阳断裂，该断裂与渭南塬前断裂、华山山前断裂共同构成渭河盆地东南缘的重要边界活动断裂带。

关键词: 1568年陕西高陵地震, 历史地震考证, 发震构造, 渭南-泾阳断裂