四川省地震重点监视防御区未来地震潜势的研究

STUDY ON SEISMIC POTENTIAL OF THE KEY REGION OF EARTHQUAKE MONITORING AND DEFENDING OF SICHUAN

本文通过历史地震及现今地震活动性的分析、活断层分段理论及地震空区理论的应用、地震平均复发间隔及复发条件概率的估算以及多学科专家综合评估方法的引入,对川西鲜水河—安宁河—则木河断裂和滇东小江断裂带(中—北段)上15个不同段落的地震潜势进行了深入的研究。进一步修正并重新圈绘出位于鲜水河—安宁河—则木河断裂带上的四川省地震重点监视防御区,其范围:北起道孚县的葛卡或者松林口一带,南至西昌市,沿鲜水河—安宁河—则木河主干断裂带展布,全长约350千米。按对未来地震震级估计的不同,该区可分成3段。第1段位于葛卡或松林口至康定之间,震级估计为7±1/4级;第2段位于康定与石棉之间,估计的震级是6(1/2)±1/4;第3段位于石棉至西昌之间,震级估计为7～7(1/2)。此外,研究结果还显示了小江断裂带上的新塘湾和寻甸—嵩明两个段落未来15年内强震发生的概率相对较高。

Based on the analysis of historical and current seisimicities, the application of theories of both active fault segmentation and seismic gap, the reckoning of average recurrence intervals and recurrence conditional probabilities for earthpqakes, and the introduction of synthetic evaluation method of multiple disciplines of experts, this paper has made a deepgoing study on the seismic potential for 15 individual fault segments along the Xianshuihe—Anninghe—Zemuhe fault zone of western Siehuan and the Xiaojiang fault zone (its middle and northern parts)of eastern Yunnan. This key region is extending from G]ka or Songlinkou Pass of Daofu county to the north to the city of Xichang to the south along the main fault zone, having a total Iength of about 350kms. This region can be divided into 3 sections according to Corresponding magnitude estimation for the future events. The Section 1 with a future magnitude estimation of 7±1/4 is at between Geka or Songlinkou pass and Kangding. The section 2 with a future magnitude estimation of 6 1/2±1/4 is at between Kangding and Shimian. The section 3 with a future magnitude estimation of 7 to 7 1/2 is at between Shirnian and Xichang. It is also suggested that two segmemts of the Xiaojiang fault zone, Xintangwan and from Xundian to Songmin, have relatively higher probabilities for ocurrenees of strong earthquakes within the coming 15 years.