北天山地区2011 年以来两次6 级地震前的地震学中短期异常特征

Mid-and short-term anomaly characteristics on seismicity before the Two M6. 0 earthquakes in northern Tianshan Mountains since 2011

摘要:

通过分析北天山地区历史强震、构造活动背景、区域应变能积累特征以及2011 年11月1 日尼勒克、巩留交界6. 0 级和2012 年6 月30 日新源、和静交界6. 6 级地震前区域地震活动异常特征等，探讨了这两次6 级地震前的地震学中短期异常特征。结果表明，2011 年6 月以来北天山地区中强以上地震处于加速活动状态，进入应变能释放阶段;尼勒克、巩留交界6. 0 级和新源、和静交界6. 6 级地震震前先呈6 级地震平静而后被打破、中强地震成组活动和空间迁移、条带和空区等较明显的中期异常;震前还出现了较为相似的4 级以上地震围空和5 级逼近地震，且逼近地震与主震发生时间间隔均为14 天，显示了较清晰的异常图像和较明显的中短期震兆特征。

Abstract:

By analyzing historical strong earthquake activity，tectonic activity background， regional strain accumulation and anomaly character on regional seismicity before the Nilka-Gongliu MS6. 0 earthquake on November 1，2011 and the Xinyuan-Hejing MS6. 6 earthquake on June 30， 2012，the article researches the mid- and short-term anomaly character on seismicity before the two MS 6. 0 earthquakes． The result shows that moderately strong earthquake activity in the northern Tianshan mountains appeared accelerated since June，2011，and entered into the strain energy release stage． There are obvious mid-term anomalies such as MS6. 0 earthquake quiescence and broken，grouping activity and space migration of moderately strong earthquakes，seismic belt and gap etc． before the 2011 Nilka-Gongliu MS 6. 0 earthquake and the 2012 Xinyuan-Hejing MS6. 6 earthquake． There appeared M ＞ 4. 0 earthquake gap and imminent earthquake with the magnitude 5. 0 before the two earthquakes，and the time intervals between the imminent earthquakes and the mainshocks were both 14 days or so，and which shows the clear abnormal images and mid- and short-term anomaly character．