四川断层活动性分析及汶川、芦山地震活动关联性研究

基于龙门山、鲜水河、安宁河-则木河断裂带上跨断层水准资料，计算不同场地年均形变速率和断层垂直形变累积率，分析断层年变速率和Dc空间分布等值线变化，揭示汶川地震前后断层活动规律、区域应变、应力场的能力聚集程度，进而探讨汶川、芦山两次地震的关联性。结果显示：1）汶川地震的发生明显加剧了龙门山断裂带中南段的断层活动性，年均形变速率由震前<1 mm/a，到震后最大达10.01 mm/a；汶川地震的发生对安宁河-则木河断裂带上的汤家坪、西昌场地影响较大，年变速率显著增加，断层活动性得到加强；2）汶川地震发生前，龙门山断裂东北段存在Dc高值区，随后Dc值逐渐减小，汶川地震的发生存在一定的应力累积背景；汶川地震发生后明显改变了整个龙门山断裂带的Dc空间分布，加速形成围绕双河场地的Dc高值环绕区，而芦山地震的震中位置位于高值与低值交界区域，空间差异较为显著。

Sichuan Fault Activity Analysis and Correlation Study of Wenchuan & Lushan Seismic Activity

The paper considers the Wenchuan and Lushan earthquakes, which occurred in the Longmenshan fault zone. Based on the cross fault leveling data of Longmenshan, Xianshuihe and Anninghe-Zemuhe fault zones, the annual deformation rate of different sites and the accumulation rate of fault vertical deformation are calculated. The analyses of the annual deformation rate and the spatial distribution of Dc contour map changes reveal the fault activity law. We ascertain the regional strain and the stress field before and after the Wenchuan earthquake, then discuss the correlation of the two earthquakes. The results show: (1) The occurrence of the Wenchuan earthquake obviously increases the fault activity in the southern tip of the Longmenshan fault zone. The average annual rate of change before the earthquake is increased by <1 mm/a, increasing to a maximum of 10.01 mm/a after the earthquake. The occurrence of Wenchuan earthquake has great impact on Tangjiaping and Xichang sites on Anninghe-Zemuhe fault zone, where the annual rate of change increases, and the activity of the fault is strengthened. (2) Before the occurrence of the Wenchuan earthquake, the northeast section of Longmenshan fault shows a high Dc value area; afterward, it gradually reduces. The occurrence of Wenchuan earthquake presents a background of stress accumulation. The spatial distribution of Dc in the Longmeshan fault zone obviously changes after the Wenchuan earthquake, accelerating the formation of a high Dc value around the site of Shuanghe site. The Lushan earthquake epicenter is located in the high value and the low value region, with a significant spatial difference.