A dense array experiment for the observation of waveform perturbations
详细信息 查看全文
- 作者：Gaffet ; Sté ; phane ; Larroque ; Christophe ; Deschamps ; Anne ; Tressols ; Florence
- 关键词：Seismological array ; Cluster analysis ; Heterogeneity ; Wavenumber ; Site effect ; Back-azimuth ; Diffraction
- 刊名：Soil Dynamics and Earthquake Engineering
- 出版年：1998
- 出版时间：October 12, 1998
- 年：1998
- 卷：17
- 期：7-8
- 页码：475-484
- 全文大小：1.49 M
文摘
We analyze observed three-component seismograms recorded by a dense array of 21 short-period receivers (f>2 Hz) installed on a homogeneous Quaternary plain with 1.5×3.5 km2 horizontal dimensions. The experiment was conducted in the district of Caille, in SE France for 3 months. The observed waveform data are related to diffraction and refraction of the direct wavefield by different geological structures and topographic morphologies surrounding the array. The origin of the coda energy following the energetic Pg or Sg arrivals is either influenced by heterogeneities close to and inside of the valley, for instance thrust of Jurassic limestones over Cretaceous marls in the northern and southern limits of the valley, or by heterogeneities located outside of the valley such as the interface unconformity between crystalline basement and sedimentary cover in the northern border of the Maures–Tanneron ranges. The main energetic arrivals of the seismograms arrive at the array with a definite range of azimuths that is not correlated with the event back-azimuth. Moreover, these arrivals do not appear with azimuths related to the characteristic NS and EW valley orientations, and thus may be related to heterogeneities located outside of the valley.