【摘要】 龙门山断裂系位于松潘—甘孜山地与成都盆地平原之间,地形高差达3500±500 m.根据重力资料给出四川中西部成都盆地、龙门山、邛崃山区、松潘等川西山地(102°E~105°E,30°N~33°N)的地壳厚度(Moho界面深度)分布.为了探究汶川大地震孕育与发生的原因,将其与据艾里(Airy)大陆均衡理论给出的理论均衡地壳厚度进行对比分析,以探讨该地区的地壳均衡状态.研究结果表明:龙门山断裂带系及以西地区深部地壳是处于很不均衡的状态.为了深化认识重力均衡与大地震的相关性,尚需对该地区深部结构与地壳重力均衡效应作精细研究.同时,本文上述研究结果亦有益于震后确定城镇布局和为不同类型建筑物重建选址方面提供深部要素.更多还原

【Abstract】 Longmenshan fault belt is located between Songpan-Garze terrane and Sichuan basin,the altitude difference of terrane is 3500±500 m.Based on the data of Bouguer gravity anomalies,the distribution of crustal thickness(Moho depth) in the Chengdu Basin,Longmenshan tectonic zone,Qionglaishan Mt,western Sichuan Mountains and their adjacent area(102°E~105°E,30°N~33°N) are obtained.For the research of the causes about brewing and generation of the Wenchuan violent earthquake,meanwhile,the theoretic isostatic crustal thickness D in this research area are obtained according to the Airy′s isostatic theory.After that,the distributions of D and Moho depth in this research area are compared mutually for probe into the crustal isostatic state.The results indicated that the deep crust in Longmen Shan fault belt and the adjacent region of its western part are in a very non-isostatic state,which means that the crust in this area is in non-stationary state.The precise crustal structure and gravity isostatic compensation of earth crust must be researched profoundly for the study of the relationship of gravity isostatic effect and violent earthquake.This research results may provide deep factors for the selection of location,re-construction of buildings, layout of towns and villages after earthquake.更多还原