东北地区地震大形势预测回溯性检验

The Retrospective Test of The Earthquake Great Situation in Northeast China

摘要:

对1998~2010年度地震大形势东北地区预测效果和预测依据进行了总结和评估分析。结果显示1998年以来东北地震大形势预测的5～6级地震危险区主要集中在环渤海、辽蒙交界和黑吉蒙交界地区。地质构造背景和地震活动实况也表明上述三个地区及邻区为东北中强震的主体活动地区，历年报告对东北危险区的把握较好，东北地震大形势第一年度趋势预测准确率为57%，1~2年度预测准确率为71%。东北地震大形势预测判据主要有8项，其中中小地震活动增强、空区和条带以及地震活动性参数扫描等3项地震学指标可靠性较高，R值评分均大于0.22。统计结果显示，预测报告中每年给出的异常指标数量与次年最大震级没有明显的关联，但中强震前中小地震活动增强是东北地区地震活动的主要特征之一。活跃—平静期、构造背景以及历史地震活动等在预测时，虚报的概率较大，二者或许对长趋势的预测起一定的借鉴作用。正确判断东北地区地震活动目前所处的状态（活跃状态还是平静状态）以及活跃—平静期转换的界定指标，可适当提高危险区预测的准确性，减少虚报率。回顾和总结的过程中也发现，目前1~3年地震形势的预测分析以统计性、定性判定依据为主，主要基于震例资料的统计和定性对比分析，反映大地震孕育和发生物理过程的资料非常有限，今后应在努力提高统计分析严谨性的同时，尽可能多地获得并采用多学科观测资料，从地球物理场动态变化的角度来分析地震趋势的发展。

Abstract:

According to the objective summary and assessment analysis of the prediction effects and criteria of the seismic situation in northeast China in 1998-2010，the risk regions of M5~6 earthquakes have been concentrated mostly in the area near the Bohai Sea-Liao-Meng juncture and the juncture of the Heilongjiang，Jilin，and Inner Mongolia provinces since 1998.Geological tectonic backgrounds and live seismic activities also show that the three regions and its adjacent regions are the main areas of moderate and strong seismic activity in northeast China. Reports during recent years offer a better understanding of the northeast risk regions.The prediction accuracy of a great northeastern earthquake situation is 57% for the first year and 71% for the second to third years.Eight main prediction criteria are used for seismic situations，including the enhancement of small and moderate earthquakes；gaps and belts；and seismic activity parameter scanning，which are three seismological indicators of higher reliability.In addition，the R value evaluation is more than 0.22.Statistics show that the number of abnormal indicators given in the annual prediction report and the maximum magnitude predicted for the subsequent year are not clearly connected.However，the enhancement of small and moderate seismic activities before moderate and strong earthquakes is one of the important features of northeastern regional seismic activities.Although the active-calm periods，tectonic backgrounds，and historical earthquake activities easily give false prediction rates，they may be used to draw lessons，particularly in long term tendency forecasting.Correct judgment of the present seismic state in northeast China，whether active or calm，and definite indices of active-calm period conversion can appropriately increase the accuracy of prediction in risk regions and reduce the rate false results.It has also been determined during the process of reviewing and summarizing that current forecast analysis of 1~3 years focuses mostly on statistical and qualitative judgment basis，and is mainly based on comparison and analysis of earthquake case statistics and qualitative analysis.Information reflecting great earthquake gestation and physical processes is very limited.In the future，we will attempt to improve the statistical analysis，obtain and utilize multidisciplinary observation data as much as possible，and analyze the development of earthquake trends from the perspective of geophysical field dynamic change.