摘要
基于有限矩形位错理论及USGS地震波反演的断层模型,结合研究区地壳-上地幔平均波速分层结构,构建均匀地壳模型,利用PSGRN/PSCMP软件模拟计算地壳分层和地壳厚度对汶川地震同震形变和重力变化的影响,模拟结果表明:地壳分层和地壳厚度对同震效应的影响与断层产状和计算点与断层相对位置有关;两模型模拟结果差异分布形式与同震效应分布类似;其差异百分比分布明显受同震效应零线制约,远离零线为正,对于地壳分层,其影响在10%～20%之间,而负影响以及正影响超过30%的则集中出现在零线附近;地壳分层对地表经向位移、纬向位移、垂直位移和重力变化的平均影响分别为18.4%、18.0%、15.8%和16.2%;地壳厚度为40km时,其对汶川同震经向位移、纬向位移、垂直位移和重力变化的平均影响分别为4.6%、5.3%、3.8%和3.8%;壳厚度为70km时,其平均影响分别为3.5%、4.6%、3.0%和2.5%。
Using the PSGRN/PSCMP software and the fault model offered by USGS and on the basis of finite rectangular dislocation theory and the local layered wave velocity structures of the crust-upper-mantle,the influences of crust layering and thickness to coseismic gravity changes and deformation of Wenchuan earthquake have been simulated.The results indicate that：the influences have relation to the attitude of faults and the relative position between calculated points and fault.The difference distribution form of simulated results between the two models is similar to the distribution of coseismic effect.For the per-centum distribution,it＇s restricted by the zero line of the coseismic effects obviously.It＇s positive far from the zero line.For the crust thickness,the effect is about 10%~20%.The negative and the effect over 30% focus around the zero line.The average influences of crust layering and thickness for the longitudinal deformation,latitudinal deformation,vertical deformation and gravity changes are 18.4%、18.0%、15.8% and 16.2%,respectively when the crust thickness is 40km,the average influences are 4.6%,5.3%,3.8% and 3.8%,while the crust thickness is 70 km,the average influences are 3.5%,4.6%,3.0% and 2.5% respectively.
出处
《大地测量与地球动力学》
CSCD
北大核心
2010年第4期29-35,共7页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(40574012)
地震科学联合基金(A07030)
关键词
汶川地震
同震效应
地壳分层
地壳厚度
有限矩形位错理论
Wenchuan earthquake
coseismic effects
crust layering
crustal thickness
finite rectangular dislocation theory
