福建地区环境噪声瑞利波群速度层析成像

Surface wave tomography of ambient seismic noise correlation in Fujian Province

摘要:

本文利用福建、广东、江西和浙江等4 省数字地震监测台网中69个宽频带台站2010年4月13日～10月13日的速度型噪声记录和互相关技术，提取两两台站间的瑞利面波格林函数，并利用层析成像技术最终反演获得了福建地区(115.7～120.5°E、23.6～28.35°N)瑞利面波群速度的分布图像。结果表明，利用该方法得到的福建地区周期为3～5s的瑞利面波群速度在2.73～3.17km/s之间，平均速度为2.96km/s。瑞利波群速度横向变化与福建地区地表构造特征和地热异常区分布情况是基本吻合的;该群速度分布图在漳州盆地和福州盆地区域表现出非常明显的低速异常，这主要是因为受到盆地沉积层和高地热的影响;杉岭地块属于山地地形，但由于受到高地热的影响，因此表现为低速异常;永安-玳瑁山地块为山地区，而受到中地热的影响，速度异常表现较为复杂。

Abstract:

The vertical correlation coefficients between two stations at intervals of 1-day are calculated with the 77 broad-band stations’microseisms records given by the Seismic Monitoring Network of Fujian，Guangdong，Jiangxi and Zhejiang Provinces from April 13，2010 to May 10， 2010. The authors got the different coefficients and added the interferential coefficients． Based on the chessboard test in seismology，the authors perform ambient noise tomography of Fujian Province (110°～123°E，21°～31°N) with the appropriate inversion matrix． The results imply that the signal-noise-ratio (SNR) increases proportional to the added times，and the group velocity of Rayleigh waves in Fujian Province is between 2.8km/s and 3.2km/s with average velocity 3.0km/s． The distribution of the group velocity is almost coincident with the topography and the geothermy of Fujian Province． But because of the effects of both the topography and the geothermy，the distribution of the group velocity in some areas is abnormal． From the group velocity distribution image，an obvious low velocity area can be found in the area of Zhangzhou basin and Fuzhou basin． It must be affected by both the sedimentary and the geothermy deposit in these two basins．