青藏块体东北缘跨断层异常场地比指标及其在地震预测中的应用

为了客观反映跨断层形变资料在地震前出现的异常程度, 减弱场地布设不均匀性造成的影响, 本文基于以往典型震例归纳跨断层异常场地比指标并进行了实例检验。 结果表明: ① 震例统计显示, 异常场地比随震中距增加快速降低, 在青藏块体东北缘5.8级及以上中强地震前, 距震中200 km范围异常场地比约为0.5。 ② 异常场地比等值线高值区对地震震中位置有较好的指示意义, 可以作为中强地震预测的一种定量判定依据, 为区域地震危险性的地点判定提供支持。 ③ 多期异常场地比空间分布特征能够较好地刻画跨断层异常随时间的增强、 减弱或迁移特征, 可为地震紧迫性判定提供一定帮助。

The Ratio of Cross-fault Anomalous Site in the Northeastern Margin of Qinghai-Tibet Block and Application in the Earthquake Prediction

In order to reflect abnormality of the cross-fault data before the earthquakes objectively, reduce the impact caused by non-uniformity of the sites layout, based on typical earthquake cases in the past, this paper summarizes the ratio of cross-fault anomalous site and tests by real earthquakes.The result shows: ① Ratio of anomalous site reduces rapidly with the epicenter distance increasing. Before the earthquake of magnitude 5.8 and above in the northeastern margin of the Qinghai-Tibet block, the anomalous site ratio within a range of 200 km from the epicenter is about 0.5. ② High value area of the anomalous site ratio contour has a good indication of the earthquake epicenter location and can be used as a quantitative criterion for earthquake prediction. ③ Multi-period spatial distribution characteristics of anomalous site ratio can describe the enhancement, attenuation or migration of cross-fault anomalies over time, which can provide some helpful for the determination of earthquake urgency.