公元600年秦陇地震考证与发震构造探讨

 公元600年12月16日,在甘肃天水与陕西陇县一带,发生1次强烈地震,造成严重的震害及社会影响。长期以来,对公元600年秦陇地震的确切震级、震中位置、震中烈度的认识存在分歧,对该次地震的发震构造不甚明确。秦陇地区位于南北地震带的北段,在构造上处于鄂尔多斯块体西南缘与青藏块体东北部的祁连断褶带之间的过渡地带。对公元600年秦陇地震详细考证,对其发震构造进行探讨,对于评定秦陇地区的地震活动性、分析其未来地震危险性有重要意义。本文收集有关公元600年秦陇地震的相关史料及研究成果,发现一些新的可能与该次地震有关的佐证资料,通过史料考证及震害分析,推断公元600年秦陇地震震中应在天水陇县之间,更靠近陇县的陕西境内,震中烈度达IX度,震级6(3/4)级左右,本次地震极震区长轴方位大致与陇县-宝鸡断裂带相吻合。经过野外实地考察,综合分析认为,公元600年秦陇6(3/4)级地震的发震构造为固关-县功断裂带的八渡-龙尾段。

Textual Research of A.D. 600 Qin-Long Earthquake and Discussion on Its Seismogenic Structure

A.D. 600 December 16, a strong earthquake occurred in an area including Tianshui, Gansu Province and Longxian, Shaanxi Province, which caused serious damage and social impact. For a long time, there were different understandings of its exact magnitude, epicenter and epicentral intensity, the seismogenic structure was also unclear. The Qin-Long area was a transitional zone between the southwestern margin of the Ordos block and the Qilian fault fold belt of northeastern Qinghai-Tibet block. It was significant to detailedly study A.D. 600 Qin-Long earthquake and discuss its seismogenic structure. The historical datum on A.D. 600 Qin-Long earthquake were collected and the previous works done by other scholars were also consulted. In Addition, A few of supporting information that was possibly related to this earthquake was discovered. Through studying the historical datum and analyzing the damages on this earthquake, the epicenter of A.D. 600 Qin-Long earthquake may located between Tianshui and Longxian, which is closer to the latter. Its epicentral intensity was inferred as IX and magnitude was about 6(3/4). The orientation of the long axis of the meizoseismal area was roughly consistent with Longxian-Baoji fault zone. By conducting the field investigation and comprehensively analyzing datum of this earthquake, the seismogenic structure of A.D. 600 Qin-Long earthquake may be concluded as Badu-Longwei segment of Guguan-Xiangong fault zone.