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Title:: Research on Goodness of Earthquake Fit Anomaly before Qinghai Menyuan M_S6.4 Earthquake in 2016

Author(s):: LI Tao¹; ZHONG Weixing²; 1. Earthquake Administration of Qinghai Province,Xining 810001,Qinghai,China2. Earthquake Administration of Shanghai Municipality,Shanghai 200062,China

Keywords:: G-R formula; goodness of earthquake fit; Menyuan earthquake; time and space scanning

摘要:: 运用G-R公式的原理,对2016年门源6.4级地震震中及周边区域进行地震拟合优度的时间和空间扫描计算。时间扫描结果显示,地震前27个月,震中及周边的地震拟合优度值发生大幅度下降并低值持续,震前2个月内再次发生明显下降直至发震。空间扫描结果显示,地震前震中及周边的地震拟合优度等值线分布明显变化,相邻2个低值区扩张并合并,震中区域乃至整个研究区域的拟合优度值明显下降。因此,在门源6.4级地震前,由于孕震过程引起应力积累导致震中区域大小震比例失调,使得震中周边区域的地震拟合优度值出现明显的低值过程。

Abstract:: The time and space scanning calculation of the goodness of earthquake fit was done in the epicenter of 2016 Menyuan M_S6.4 earthquake and its adjacent area by the principle of G-R formula. The time scanning results show that the goodness of earthquake fit values were decreased significantly and continued to keep the lower value in the epicenter and its adjacent area in 27 months before the earthquake,then the value has been significant decreased again within two months before the earthquake. The space scanning results show that the distribution of goodness of earthquake fit contours have significant changes in the epicenter and its adjacent area before the earthquake and two adjacent low-value zone have expansion and consolidation,the goodness of fit value decreased significantly in epicenter region and the entire study area. All of these results show that the accumulation of the stress in the seismogenic process leads to the imbalanced proportion of the small and large earthquakes before the earthquake,so that the goodness of fit values appear low values in the epicenter and its adjacent area.