Seismic site characterization of the Kastelli (Kissamos) Basin in northwest Crete (Greece): assessments using ambient noise recordings
Seismic site characterization of the Kastelli (Kissamos) Basin in northwest Crete (Greece): assessments using ambient noise recordings
复制标题
克里特岛（希腊）西北部卡斯特利（基萨莫斯）盆地的地震现场特征：使用环境噪声记录进行评估
DOI：
--
复制
发表时间：
2015
影响因子：
4.6
通讯作者：
P. Collins
中科院分区：
文献类型：
--
作者：
M. Moisidi;F. Vallianatos;S. Kershaw;P. Collins
克里特岛是活跃的地震和现场反应的研究，需要估计当地的现场条件受到地震活动。为了收集基本数据，我们进行了环境噪声记录，以估计在克里特岛西北部的小规模卡斯泰利盆地的表面和近地下结构的现场响应。盆地中心调查点的空间水平与垂直频谱比（HVSR）共振模式由一个或两个峰值组成，在不同地点分为低到高频率范围，如下所示：（a）在某些地点，只有一个低频放大峰（B）在其它位点中仅在中频（2.9-8.5 Hz）处有一个放大峰，和（c）在其它位点中在低至高频范围（0.6-15.5 Hz）处有两个放大峰。在0.6- 15.5Hz的频率范围内，所研究的站点被放大，而振幅在频谱比中达到4倍。低频的一个HVSR放大峰与局部较软或较厚的第四系沉积物有关。在盆地西北部沿海的一个石化良好的白垩纪石灰岩场地测量到了微震，该场地的特征是断裂和断层主要在NNE至NNW方向。一个中频放大峰的位置由沿海的西北向西南延伸，描绘出走向北北西的构造。这两个放大的峰值归因于浅层地下不均匀性/不规则性，局部引起的断层带和上覆的第四纪沉积物。空间HVSR的频率和HVSR形状的变化描绘了四个结构罢工NNE，NNW和在一个部门西北到WNW，横切人口稠密的盆地表明，微震可能是一个有价值的工具，至少为Kastelli-Kissamos盆地提供一个第一近似的断层带划定。该盆地被归类为希腊地震规范2000的X土壤类别。
Crete is actively seismic and site response studies are needed for estimating local site conditions subjected to seismic activity. In order to collect basic data, we performed ambient noise recordings to estimate the site response of the surface and near subsurface structure of the small-scale Kastelli Basin in northwest Crete. The spatial horizontal to vertical spectral ratios (HVSR) resonance pattern of the investigated sites in the centre of the Basin consists of either one or two peaks divided into low to high frequency range in different sites as follows: (a) in some sites only one amplified peak at low frequencies (0.6–1.2 Hz), (b) in other sites only one amplified peak at medium frequencies (2.9–8.5 Hz) and (c) in yet other sites two amplified peaks in the low to high frequency range (0.6–15.5 Hz). The investigated sites are amplified in the frequency range 0.6–15.5 Hz, while the amplitude reaches to a factor of 4 in the spectral ratios. The one HVSR amplified peak at low frequencies is related to locally soft or thick Quaternary deposits. Microtremors were measured in the coastal northwest part of the Basin in a well—lithified Cretaceous limestone site characterized by fractures and faults striking predominantly in a sector NNE to NNW. Sites of one amplified peak at medium frequencies are extended from coastal northwest to southwest delineating a structure striking to NNW. The two amplified peaks are attributed to shallow subsurface heterogeneities/irregularities, locally induced by fault zones and to the overlying Quaternary deposits. Spatial HVSR variations in the frequency and HVSR shape delineate four structures striking NNE, NNW and in a sector NW to WNW, crosscutting the dense populated Basin suggesting that microtremors could be a valuable tool for providing a first approximation of fault zone delineation at least for the Kastelli-Kissamos Basin. The Basin is classified into the X soil category of the Greek Seismic Code 2000.