利用伸缩仪观测体应变资料检测地球自由振荡

Detecting the free oscillation of the earth by use of observational data of extensometer to volume-strain-meter

将湖州地震台数字伸缩仪线应变观测数据转换成体应变数据,采用功率谱密度估计方法,资料未进行去固体潮处理,准确获得2011年3月11日日本大地震激发的0S4-0S30基频球型自由振荡,对照PREM模型的理论计算周期,发现观测资料周期与之符合较好。

By using digital observations of extensometer to volume-strain-meter at Huzhou station and with power spectrum density estimationg method, 0 S4--0 S30 fundamental sphere free os- cillations caused by Japan earthquake on llth Mar. ,2011 were obtained, without deleting in- fluence of the earth tide on the data. Then comparing it with theoretical periods of PREM model, we find that they are in very good accordance with each other. This proves that ex- tracting the free oscillation of the Earth from the data of digital extensometer to volume- strain-meter is a new approach.