川滇地区应力场演化与强震间相互作用的三维有限元模拟
摘要
针对川滇地区 ,在大量搜集、总结前人资料和结果的基础上 ,建立了包括上地壳、下地壳 (两层 )、上地幔等 4层结构的三维有限元模型 .通过反复调试 ,确定了其边界条件 ,并且计算了川滇地区背景应力场、断层蠕动产生的应力场和强震触发的应力场 ,以及它们的动态变化 .结果表明 :后续地震大多发生在前面地震引发的库仑破裂应力正值区 ,前一地震对后续地震有一定的触发作用 ,强震是在较高的应力背景下成组发生的 .这对判断、识别地震异常 ,提高地震预测水平有着很大的意义 .
Based on the latest achievement about activities of geological structure, a 3-D finite-element model containing four layers of upper crust, lower crust (two layers) and upper mantle is established in the paper. By repeated tests and revisions, the boundary conditions of the model are determined. And then the background stress field, the stress field caused by fault creep and the stress field triggered by strong earthquake in Sichuan-Yunnan region, as well as their dynamic variations are calculated. The results indicate that the latter earthquake often occurs in the area with positive Coulomb rupture stress changeassociated with the former one, the former earthquake has a triggering effect on the latter one to a certain extent, and strong earthquake often occur in groups under the background of high stress, which is of great significance for distinguishing seismic anomalies, as well as for improving the level of earthquake prediction.
Based on the latest achievement about activities of geological structure, a 3-D finite-element model containing four layers of upper crust, lower crust (two layers) and upper mantle is established in the paper. By repeated tests and revisions, the boundary conditions of the model are determined. And then the background stress field, the stress field caused by fault creep and the stress field triggered by strong earthquake in Sichuan-Yunnan region, as well as their dynamic variations are calculated. The results indicate that the latter earthquake often occurs in the area with positive Coulomb rupture stress changeassociated with the former one, the former earthquake has a triggering effect on the latter one to a certain extent, and strong earthquake often occur in groups under the background of high stress, which is of great significance for distinguishing seismic anomalies, as well as for improving the level of earthquake prediction.
引文
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丁国瑜,卢演俦.1986.对我国现代板内运动状态的初步讨论[J].科学通报,31(18):1412～1413
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阚荣举.1980.西南地区现代构造应力场与板内强震活动[J].地震研究,3(3):45～59
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马杏垣.1989.中国岩石圈动力学地图集[M].北京:中国地图出版社,1～11
钱洪,沈均礼,黄进,等.1980.西南地区近代构造应力场和地壳运动特征的实验研究[J].地震研究,1(3):60～67
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许忠淮,汪素云,黄雨蕊.1987.由多个小震推断的青甘和川滇地区地壳应力场的方向研究[J].地球物理学报,30(5):476～486
鄢家全.1979.中国及邻区现代构造应力场的区域特征[J].地震学报,1(1):9～24
MolnarP ,TapponnierP .1975.CenozoictectonicsofAsia:effectsofacontinentalcollision[J].Science,189:419～426
TapponnierP ,MolnarP .1976.Slip linefieldtheoryandlargescalecontinentaltectonics[J].Nature,264～319
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