地震视应力在中国大陆西部强震趋势预测中的应用

以中国大陆西部(20°~50°N, 73°~105°E)为例, 以中国地震台网中心月报目录为基础, 参照美国哈佛大学(CMT)逐个筛选出1990年1月1日至2005年12月31日中国大陆191个地震作为样本, 对用哈佛大学提供的地震矩和震级能量公式计算的视应力值σ_app1与完全由震级经验公式估算出的地震矩和地震辐射能量计算出的视应力值σ_app2进行了对比分析。 在此基础上, 通过对1970年以来中国大陆7级以上强震的震例总结, 对地震视应力异常区与强震发生地区的关系进行了研究。 并结合钻孔应力、 应变学科在年度预测中对中国大陆西部强震发生地区的预测情况进行了R值评分。 结果表明: ① 当震级上限固定时, σ_app1与σ_app2的差值序列之方差, 表现出随着震级下限增大而增大的特征。 在3.5≤M_S≤6.0区间内, σ_app1与σ_app2拟合程度较好。 ② 地震视应力异常区的变化与迁移可能是构造大区应力、 应变场中显著应力变化区的变化与迁移的反映, 具有图像直观、 量化、 预测区间有限等优点, 可用于强震发生地区的预测, R值约为0.35。 并对强震发生地区趋势预测的总体思路进行了有意义的讨论。

Application of apparent stress to macroseism tendency prediction in western China's mainland

This paper takes western China's mainland (20°~50°N, 73°~105°E)as an example, based on the monthly earthquake catalogue of CENC and referring to the Harvard CMT catalogue, chooses 191 earthquakes in China's mainland from January 1, 1990 to December 31, 2005 to compare the apparent stress value σ_app1 which are calculated by using Harvard's seismic moment and magnitude-energy expressions with the apparent stress value σ_app2 which are calculated by using the magnitude experiential expressions only. Based on that, this paper researched the relation between apparent stress anomalous area and macroseismic area through summarizing macroseism M_S≥7 in China's mainland since1970 and graded the R-value according to the macroseism area prediction of ICD yearly prediction report. The result shows that, ① When the magnitude upper limit is fixed, the variance of difference sequence between σ_app1 and σ_app2 increases along with the magnitude lower limit increase. In 3.5 ≤M_S ≤ 6.0 sectors, the fitting degrees of σ_app1 and σ_app2 are better. ② The change and migration of apparent stress anomalous area is possibly the reflection of the change and migration of the remarkable stress variation area in the whole structure stress area. It have many advantages, for example, the picture may directly view, it can be quantified, the prediction of area is limited and so on, which could be used to predict the microseism area. The R-value approximately is 0.35. Finally, this paper discusses the idea on the tendency prediction of macroseism area.