各向同性膨胀点源模拟长白山火山区岩浆囊压力变形源  

Modelling pressurized deformation source for Changbaishan volcano with homogenous expansion point source

作　　者：朱桂芝[1] 王庆良[2] 石耀霖[1] 崔笃信[2] 

机构地区：[1]中国科学院研究生院计算地球动力学实验室,北京100049 [2]中国地震局第二监测中心,西安710054

出　　处：《地球物理学报》2008年第1期108-115,共8页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(40574041)资助

摘　　要：2002-2003年长白山火山区的水平运动缺乏中心对称性分布特征,本文采用同一深度沿三个互相垂直方向拉张的点源模式模拟了长白山火山区的岩浆囊压力变形源.在介质参数为Vp=6.700km/s,Vs=3.8700km/s,ρ=2900kg/m^3的均匀弹性半空间中,联合利用2002-2003年长白山火山区的GPS观测数据和水准数据,结合PSGRN/PSCMP代码和遗传算法反演长白山火山区的压力变形源特征.反演结果表明,由三个垂直的不等量扩张方向确定的椭球状点源模型可以较好地模拟长白山火山区岩浆囊压力变形源.岩浆囊深处9.2km,在走向为34.4°,倾角为82.2°的断层面的法向方向体积扩张量最大,达到7000000m^3;在走向为302.8°,倾角为78.5°的断层面的法向方向体积扩张量次之,达到6598071m^3;在走向为337.7°,倾角为14.0°的断层面的法向方向体积扩张量最小,达到5220160m^3.Pressurized deformation source is modeled by using three mutually orthogonal extensional point sources at the same depth, based on the fact that horizontal displacements in Changbaishan volcanic region during 2002 - 2003 lacked centric symmetric distribution caused by spherical pressurized magma source. In homogenous elastic half-space with the parameter Vp = 6.700 km/s, Vs = 3.8700 km/s, ρ = 2900 kg/m^3 , the pressurized deformation source in Changbaishan volcanic region is inversed with PSGRN/PSCMP code and genetic algorithm by jointly using GPS data and leveling data during 2002 - 2003. The results show that ellipsoid point source model controlled by unequal tensile ones in three orthogonal directions can represent magma source in Changbaishan volcanic region. Magma source is located in about 10 km depth, the largest volume expansion is up to 7000000 m^3 in the direction normal to the fault plane with strike angle 34.4°, and dip angle 82.2°, the second one is 6598071 m^3 in the direction normal to the fault plane with strike angle 302.8°, and dip angle 78.5°,the last one is 5220160 m^3 in the direction normal to the fault plane with strike angle 337.7°, and dip angle 14.0°.

关 键 词：长白山火山区 椭球点源模型 遗传算法 联合反演 

分 类 号：P353[天文地球—空间物理学]