钻孔差应变仪观测的苏门答腊大地震激发的地球环型自由振荡  

Earth’s free torsional oscillations of the great Sumatra earthquake observed with borehole shear strainmeter

作　　者：邱泽华[1] 马瑾[2] 池顺良 刘厚明[4] 

机构地区：[1]中国地震局地壳应力研究所,北京100085 [2]中国地震局地质研究所,北京100029 [3]河南省鹤壁市地震局,河南鹤壁458000 [4]山东省地震局泰安地震台,山东泰安271000

出　　处：《地球物理学报》2007年第3期797-805,共9页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(40374011);地震科学联合基金项目(1040037)资助

摘　　要：我们率先用钻孔应变仪观测资料研究了地球自由振荡．泰安地震台有差应变和体应变两种钻孔应变观测仪器，都观测到2004年12月26日苏门答腊大地震激发的地球自由振荡．体应变仪观测到地球的球型振荡，而差应变仪观测到地球的环型振荡．两种观测还记录到环型振荡与球型振荡相互的耦合作用．观测也记录到明显的一些振型的谱线分裂现象．用直接观测到的高质量的环型振荡资料求解了0T8-0T19等主要振型的Q值．根据两个方向的剪应变观测数据，求解了环型振荡的最大剪应变方向，发现这个方向是相当稳定的．这种研究表明，高精度钻孔应变观测仪是一种理想的地壳形变观测仪器，可以为地球自由振荡研究提供更丰富的信息．We first studied Earth＇ s free oscillations using observations of borehole strainmeters. Two kinds of borehole strainmeters at the Tai＇an Observation Station, TJ dilatometer and RYR shear strainmeter, both have observed the Earth＇ s free oscillations excited by the great Sumatra earthquake occurred on December 26, 2004, with dilatometer for spheroidal modes and shear strainmeter for torsional modes. They also observed coupled modes as well as split modes. Q-values of 0T8 - 0T19 are determined from high-quality data of torsional oscillations. According to recordings of the RYR borehole shear strainmeter in two perpendicular directions, the torsional oscillation symmetrical axis orientation of the earthquake is calculated and found to be quite steady with time and modes. High-precision borehole strainmeter proved to be ideal for crustal deformation observation and able to provide unique data for researches of Earth＇ s free oscillation.

关 键 词：钻孔应变仪 差应变仪 地球自由振荡 环型振荡 品质因子 

分 类 号：P541[天文地球—构造地质学]