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| 一种低频地震事件的检测方法在汶川地震和芦山地震前的初步应用 | |
| 引用本文： | 梁建宏,刘杰,杨文,邓菲.一种低频地震事件的检测方法在汶川地震和芦山地震前的初步应用[J].地震,2015,35(1):1-10. |
| 作者姓名： | 梁建宏 刘杰 杨文 邓菲 |
| 作者单位： | 1.中国地震台网中心, 北京 100045; 2.中国地震局地震预测研究所, 北京 100036 |
| 基金项目： | “十二五”国家科技支撑计划项目 |
| 摘 要： | 本文发展了一种单台检测低频地震事件的方法, 并用其检测2008年汶川MS8.0地震、 2013年芦山MS7.0地震震前的低频事件。 使用汶川地震、 芦山地震前周边的宽频带台站数月的垂直向连续波形, 经过2~8 Hz带通滤波、 窗长为10 s的包络平滑、 窗长为20 min的中值滤波, 去除近场天然地震及远场大震与低频噪声的影响后, 发现这两个大地震前有少数台站在连续数天的时间内, 出现持续时间长(数十分钟到数小时)、 包络中值明显大于背景噪声的现象, 其波形记录及包络特征与非火山震颤(NVT)的波形记录及包络特征具有较好的相似性, 我们认为这是汶川地震和芦山地震前的疑似慢地震事件。 初步应用表明, 本文所用的方法对于从宽频带连续波形资料中提取NVT信号是可行的。 |
| 关 键 词： | 慢地震 地震波形 中值滤波 汶川地震 芦山地震 |
| 收稿时间： | 2014-02-24 |
An Algorithm for Detecting Low-frequency Seismic Event and Preliminary Applications |
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| LIANG Jian-hong,LIU Jie,YANG Wen,DENG Fei.An Algorithm for Detecting Low-frequency Seismic Event and Preliminary Applications[J].Earthquake,2015,35(1):1-10. | |
| Authors: | LIANG Jian-hong LIU Jie YANG Wen DENG Fei |
| Institution: | 1. China Earthquake Networks Center, Beijing 100045, China; 2. Institute of Earthquake Science, CEA, Beijing 100036, China |
| Abstract: | An algorithm for detection of lowfrequency seismic event is developed and applied to detect lowfrequency event before the 2008 Wenchuan and the 2013 Lushan earthquakes. Continuous verticalcomponent waveforms of some broad band stations in a few months surrounding the Wenchuan earthquake and Lushan earthquake have been processed by applying a bandpass filter in 2—8 Hz, converted to envelopes with a smoothing time of 10 s window and a median filter with a 20 min window. As a result, teleseismic, longperiod noise and local small earthquakes are removed, the filtered amplitude is obviously larger than that of noise and last for a dozen of minutes to several hours during a few days for a small number of stations before the Wenchuan earthquake and Lushan earthquake, respectively. The waveform and envelope are similar to that of nonvolcanic tremor (NVT), we think they are suspected NVT before the two earthquakes. Preliminary application demonstrates that this algorithm is potentially useful for extracting NVT signal from continuous seismic waveforms. |
| Keywords: | Slow earthquake Seismic waveform Envelope Wenchuan earthquake Lushan earthquake |
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