云南漾濞M_(S)6.4地震信号的旋转和平动分量面波记录分析研究

Rotational and translational motions induced by the M_(S)6.4 Yunan Yangbi earthquake recorded by co-located FOGs and seismometer

旋转分量是地震波场的重要组成部分,可以为地球内部结构成像和震源参数测定等研究提供基础信息,然而缺少高精度的观测仪器,其应用受限.新发展的高精度光纤陀螺为测量旋转分量提供了一个较为可行的方案,其性能需要进一步验证.为此,武汉大地测量国家野外科学观测研究站利用两个光纤陀螺和一个宽频带地震仪组成了多分量观测系统,并开展了观测工作,记录到了云南漾濞地震的Love波信号.基于Love波信号的垂向旋转速度记录和切向加速度记录,开展了Love波视速度和到达方位角度测算分析.结果表明视速度存在明显频散特性,测算值与其他方法测算值相当,到达方位角接近大圆路径预测值,尾波部分到达角偏离较大.由此表明高精度的光纤陀螺可以用于区域震监测,结合地震仪可形成多分量观测系统,为地震学研究提供有效数据.

As a part of ground motion,the rotational component provides important additional constrains for signal processing,interior structure and source mechanism studies.However,the lack of high precision instrument limits related applications.Recently,the new developed fiber-optic gyroscope(FOG)is used a portable and inexpensive rotational seismometer.Wuhan National Geodetic Observatory deployed two FOGs and one three-components broadband seismometer on same base plate to continuously record seismic signals.This Love wave excited by the M;6.4 Yunnan Yangbi earthquake clear emerges on the records of this multiple-component seismometer.The apparent velocity and incident angle are obtained from comparison between the vertical rotation rate and the tangential acceleration records.The apparent velocities show clear dispersive and are in reasonable scale.The incident angle of the Love wave is close to the great-circle and the incident angle of the coda wave is more scattered.This study suggests that the collocated FOGs and seismometer can provides useful information for studies on interior structure and other aspects of seismology.