姑咱地震台张应变异常信号与修路施工间关系探讨

Discussion on the relationship between the abnormal signal of tensional strain and the construction of road repair at Guza station

与2008年5月12日汶川M_(S)8.0地震时记录到的大量压应变异常信号不同,2013年4月芦山M_(S)7.0地震前后姑咱地震台钻孔应变仪记录到的却是显著张应变异常,特别是临震前几日信号大幅度突升,而该时段恰巧台站大门前进行修路施工,这究竟是地球物理异常还是干扰,一直有很大争议。研究发现,这些异常信号在时间上具有高度的准同步性,即都发生在白天8:00—10:00或7:30—17:00之间,这正是工人的上班时间,而自然力产生的异常应具有随机性特征,不应有较强规律性;其次,临震前的异常振幅比芦山地震本身产生的振幅还大2倍,将其视为地球物理异常也有违常理。又结合腾冲地震台钻孔应变观测干扰实例进行分析,认为尚不能排除该张应变异常为施工干扰的可能性。

Different from a large number of abnormal signals of compressive strain recorded in the Wenchuan M_(S)8.0 earthquake in May 2008,significant tensional strain abnormal signals were recorded by a borehole strainmeter before and after the Lushan M_(S)7.0 strong earthquake in April 2013 at Guza seismic station.Especially,signal amplitude significantly enlarged a few days before the earthquake.The time period coincides with the road construction before the station gate.There has been a lot of controversy on whether it is a precursor or a disturbance.It is found that these abnormal signals have high quasi synchronization in time.They all appeared at 8:00—10:00 or 7:30—17:00 in the daytime.This is the time for the workers to work.And the abnormality produced by the natural force should have the characteristic of randomness,and it should not have such a strong regularity.Secondly,the abnormal amplitude before the earthquake is 2 times larger than that produced by the Lushan earthquake,which is counterintuitive to be regarded as a precursor.Based on the analysis of the interference examples of borehole strain observation at the Tengchong station,it is believed that the possibility of construction interference cannot be excluded.