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Title:: Characteristics of Strong Earthquake Activity in Northwest Yunnan and Study on Short-term Earthquake Precursor

作者:: 刘翔¹; 吴国华¹; 付虹¹; 单连君²; (1.云南省地震局,昆明 650224; 2.云南大学资源环境与地球科学学院,昆明 650091)

Author(s):: LIU Xiang¹; WU Guo-hua¹; FU Hong¹; SHAN Lian-jun²; (1.Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)(2.College of Resources,Environment and Earth Science,Yunnan University,Kunming 650091,Yunnan,China)

Keywords:: strong motion earthquake; earthquake precursor; short term; supporting

摘要:: 根据历史地震资料研究了滇西北强震活动韵律特征及最近10多年来6.0级以上强震前震中附近中小地震活动空间演化图像。对1986年以来滇西北5.0级以上中强震前该地区M≥3.0和M≥4.0地震的活跃和平静异常以及3级以上震群进行了清理和配套性研究,定量地给出了滇西北强震短期震兆指标。得到以下主要结果:滇西北6.0级以上强震前,在全省4.0级以上地震平静异常阶段或3.0级以上地震活跃阶段,震中附近3级地震比较活跃,并形成明显的条带、围空、密集等地震活动有序分布异常图像; 滇西北6.0级以上地震短期异常综合预报量Y≥0.56。短期震兆模型可分为两种:①滇西北3.0级以上地震活跃异常和3～4级震群活动同时出现; ②滇西北4级以上地震出现平静异常后又出现3.0级以上地震平静异常。

Abstract:: Based on the historical earthquake data, we study the rhythm of strong seismicity in Northwest Yunnan and get the medium-sized earthquake space evolution images in the neighboring region of epicenters before the M≥6.0 strong quakes occurred in Northwest Yunnan over the past decade. According to the M≥5.0 strong quakes since 1986, we study the activity and equability anomaly of the M≥3.0 or M≥4.0 earthquakes, and the M≥3.0 clusters. The index of short precursor of strong earthquake in northwest Yunnan is given quantitatively. The main results show:(1)before the M≥6.0 quakes occurred in Northwest Yunnan, the M≥4.0 were in equability and M≥3.0 were in activity, the M_S3.0 quakes around the potential epicenter were in activity, so the abnormal images of orderly distribution of seismic activity were given including the obvious band, void and intensive areas;(2)the integrated forecasting index Y of the quakes above 6 in short term anomaly in Northwest Yunnan is equal to or greater than 0.5. There are two types of short term precursor model; type one, the anomaly of activity of earthquakes with M≥3.0 appear synchronously with the clusters of earthquakes with 3.0≥M≥4.0. Type two, in the process of the tranquility of the M≥4.0 earthquakes, there are intermittent tranquility of M≥3.0 earthquakes.