基于PI法的门源MS6.4地震前震中附近地震热点图像异常变化研究

基于1980年以来青海省和甘肃省区域地震台网的定位地震目录，分析了研究区最小完备震级，选取空间网格尺度为0.2°×0.2°、地震活动异常学习时间段和预测时间段均为3 a，应用图像信息（PI）法，分析了门源M_S6.4地震发生前震中附近地震热点图像的异常变化过程。结果表明，在2013年1月1日至2016年1月1日的预测时间窗内，冷龙岭断裂和祁连山北缘断裂附近存在明显的地震热点，且地震热点图像颜色偏深，发震概率较高，向前滑动至2014年1月1日至2017年1月1日，2015年1月1日至2018年1月1日和2016年1月1日至2019年1月1日3个预测时间窗，此两断裂附近仍存在地震热点，地震热点图像颜色逐渐由深变浅，而门源M_S6.4地震就落在PI法得到的地震热点内。门源M_S6.4地震前存在明显的地震热点，且地震热点相对集中，地震热点图像颜色由深变浅，震后消失；在祁连山北缘断裂附近，地震热点持续存在，分布较集中，地震热点图像颜色也呈由深变浅的过程。未来需关注祁连山北缘断裂，附近有发生强震的可能。

A Study on the anomalous seismic activities in the Menyuan region and its adjacent areas before the Menyuan MS 6.4 earthquake by the pattern informatics (PI) method

Choosing completeness magnitude of the concerned area,the PI method is applied to study the earthquake catalogues of Qinghai and Gansu regional seismic networks since 1980,to detect the existence of earthquake hotspots before the Menyuan M_S6.4 earthquake on January 21,2016.It chooses the grid size of 0.2°×0.2° and take the learning window and forecast window of 3 years.The results show that obvious earthquake hotspots appeared in the Lenglongling fault and northern Qilian Mountain fault from January 1,2013 to January 1,2016,and the color of the hotspots appears darker,earthquakes occur with high probability. Moving forward the time period of forecast window from January 1,2014 to January 1,2017,January 1,2015 to January 1,2018,and January 1,2016 to January 1,2019,there are still hotspots in these two regions,and the color of the hotspots becomes lighter year by year.The Menyuan M_S6.4 earthquake took place within the hotspots calculated by PI method.In summary,there are obvious earthquake hotspots before the Menyuan M_S6.4 earthquake,and their locations were relatively concentrated. The color of the hotspots image changed from dark to light,and finally disappeared after the earthquake.In addition,there are still earthquake hotspots distributed near the northern Qilian Mountains fault,and the color of these hotspots also shows an evolution process from dark to light,which may lead to strong earthquakes in this region.