基于重力仪静态观测数据研究长宁6.0级地震活动性

Research on Seismic Activity of Changning Ms 6.0 Earthquake Based on the Static Observation Data of Gravimeter

地震活动突然爆发改变了地下岩石的空间位置以及密度分布形态,从而引起观测重力值的变化。通过对长宁6.0级地震重力静态观测数据的分析,发现地震发生时不一定会检测到重力值的变化,但能检测到仪器记录标准差(S.D.值)读数的变化,发震时检测到的重力变化往往是地震的震动效应导致的重力仪读数畸变。通过对长宁6.0级地震及几次典型余震的重力观测曲线和S.D.值观测曲线分析,认为当地震震动噪声处于较高水平时,观测时段内出现很多高频重力信号,当高频噪声无法消除,重力观测数据质量不可信,而这种高频干扰信号的强弱能通过S.D.值的变化来反映,从而可以通过S.D.值来研究地震活动性,并通过S.D.指标来判断单次地震活动持续时间。

The sudden eruption of seismic activity changes the spatial location and density distribution of underground rocks,which results in the change of gravity value.Through the analysis of the static gravity observation data of Changning Ms 6.0 earthquake,it is found that the change of gravity value may not be detected when the earthquake occurs,but the change of the standard deviation(S.D.value)of instrument record can be detected.The variation of gravity detected during the earthquake is often due to the reading distortion of gravimeter caused by the vibration effect of the earthquake.Through the analysis of the gravity observation curve and the S.D.value observation curve of the Changning Ms 6.0 earthquake and several typical aftershocks.It is believed that when the seismic vibration noise is at a high level,a lot of high-frequency gravity signals appear in the observation period.When the high-frequency noise cannot be eliminated,the quality of gravity observation data is not reliable,and the strength of this high-frequency interference signal can be reflected by the change of the value of S.D.Therefore,the value of S.D.can be used to study seismic activity,and the index of S.D.can be used to judge the duration of a single seismic activity.