汶川地震区断层围陷波探测

Observation of fault zone trapped waves in Wenchuan Earthquake region

对汶川地震区开展震后科考和断层围陷波探测，本文主要介绍平通镇断层围陷波探测及初步结果。平通镇处在汶川8．0级地震断层带正上方，地表破坏十分严重。该断层围陷波测线横跨断层，以地震探槽为大致中点，沿NW—SE方向两端延伸，测线长约400m。这次观测结果表明，在汶川8．0级地震的新破裂带中可以观测到断层围陷波，反映了断层带内外的介质在物理性质上有较大的差异。该测线记录的断层围陷波优势频率大约为3—4Hz。探槽附近的台站断层围陷波较强，初步推测，该地段地壳内断层的宽度大约有200m。

After the 2008 Wenchuan 8. 0 Earthquake we have done some field investigation at the epicenter region and made a survey using fault zone trapped waves. This paper gives a brief introduction about our survey at Pingtong Town and its preliminary results. Pingtong Town locates just over the fractured zone of the 2008 Wenchuan 8.0 earthquake and the damage at the surface is very serious. The observational line crosses the fractured zone. With its middle point at an earthquake exploration trough, the observational line stretches to the two sides with NW - SE direction. The total length is about 400 m. The results show that the fault zone trapped waves from the fractured zone of the 2008 Wenchuan 8.0 Earthquake are observed. That indicates the great difference. The predominant frequency of the fault zone trapped waves is about 3-4 Hz. It is stronger near the exploration trough. The width of the fault zone in the crust in this region is estimated to be 200 m.