Extracting Anomaly of the Wenchuan Earthquake from the Dilatometer Recording at NSH by Means of Wavelet-Overrun Rate Analysis
详细信息
- 责任者：Qiu Zehua (Institute of Crustal Dynamics ; China Earthquake Administration ; Beijing 100085 ; China) ; Tang Lei
- 刊名：Chinese Journal of Geophysics
- 出版年：2012
- 卷期：55(2)
- 关键词：小波变换 ; wavelet transform ; 地震前兆 ; precursor ; 四川 ; Sichuan Province
- 页码：p.538-546
- 图表：9 illus., 19 refs.
- 分类号：0500
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
By means of wavelet decomposition and the help of a modified Overrun Rate Analysis (ORA), the tiny anomaly can be extracted from the raw data. Generally, a band-passed signal obtained with wavelet decomposition can be divided into two parts: normal “background” and abnormal “bad points”. An approach to locate the objective as well as exact distinction between the two parts has been developed for the determinate threshold of ORA. According to the analysis, the extent of strain anomaly along the seismic fault of the Wenchuan earthquake 2008 is much larger than previously recognised. The anomaly is characterized by small pulses in consistence with peaks of Earth Tide, providing a clue to search for its mechanism.