...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of geodynamics >Crustal Shear-wave Splitting In The Epicentral Zone Of The 2001 Mw 7.7 Bhuj Earthquake, Gujarat, India
【24h】

Crustal Shear-wave Splitting In The Epicentral Zone Of The 2001 Mw 7.7 Bhuj Earthquake, Gujarat, India

机译：印度古吉拉特邦2001 Mw 7.7 Bhuj地震震中的地壳剪切波分裂

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We report here crustal shear-wave anisotropy, ranging from 1% to 10.76% with an average of 2.4% in the aftershock zone of the 2001 Bhuj earthquake, Gujarat, India, from a study of leading shear-wave polarization directions (LPSDs), which vary on average from NNW-SSE to E-W with a delay of 0.07-0.14 s. The delays in the NNW-SSE to NE-SW directions observed at seven stations, near the seismogenic fault, suggest cracks parallel to the direction of the maximum horizontal regional compressional stress prevailing in the region, suggesting a dilatancy-induced anisotropy resulting from approximately stress-aligned parallel vertical micro-cracks. In contrast, the LPSDs at Ramvav, Rapar and Vondh stations, away from the seismogenic fault, are fault parallel, approximately E-W and almost orthogonal to the stress-aligned polarizations inferred elsewhere. The maximum average time delay of 0.14 s is observed at Lodai, where the fast polarization direction is found to be N338°W. This has been observed from anisotropic poro-elastic (APE) modelling and observations that these are 90° flips in shear-wave polarization, resulting from propagation through micro-cracks containing fluids at critically high pore-fluid pressure surrounding the hypocenter of the 2001 mainshock. The presence of high pore-fluid pressure in the seismogenic fault zone could also explain the observed scatter in shear-wave time delays. Further, the coincidence of the N-S trending intrusive bodies (as inferred from tomographic studies in the area) with the N-S direction of regional maximum horizontal compressional stress supports the interpretation of stress-aligned vertical extensive-dilatant anisotropic (EDA) cracks. The depth distribution of the estimated anisotropy (1-10.76%), b-values and stress drop values suggests an increase at 18-30 km depths, which could be attributed to high pore-fluid pressures resulting from a fluid-filled fractured rock matrix or open micro-cracks (characterized by high crack density and high porosity) coinciding with a low velocity zone (at 18-30 km depths) as delineated from tomographic studies in the area.
机译：根据对领先的剪切波极化方向（LPSDs）的研究，我们在此报告了2001年印度古吉拉特邦布吉地震余震带的地壳剪切波各向异性，范围从1％至10.76％，平均为2.4％，从NNW-SSE到EW平均变化，延迟时间为0.07-0.14 s。在地震发生断层附近的七个台站观察到的NNW-SSE到NE-SW方向的延迟表明，裂缝平行于该地区盛行的最大水平区域压应力的方向，这表明由近似应力引起的由剪胀引起的各向异性对齐的平行垂直微裂纹。相反，Ramvav，Rapar和Vondh站的LPSDs远离断层，平行于断层，近似E-W，几乎垂直于在别处推断的应力取向极化。在洛代观测到最大平均时间延迟为0.14 s，在该区域中，快速极化方向为N338°W。从各向异性孔隙弹性（APE）建模和观察中已经观察到，这是剪切波极化的90°翻转，这是由于通过微裂纹的传播而引起的，该裂纹包含处于2001年主震震源中心的临界高孔隙流体压力的流体。在地震发生断层带中存在高孔隙流体压力，这也可以解释在剪切波时间延迟中观测到的散射。此外，N-S趋势侵入体（从该区域的层析成像研究推断）与区域最大水平压缩应力的N-S方向的重合支持了应力对齐的垂直大膨胀各向异性（EDA）裂纹的解释。各向异性估计值的深度分布（1-10.76％），b值和应力降值表明在18-30 km深度处有所增加，这可能归因于充满流体的裂隙岩体造成的高孔隙流体压力或微裂纹（以高裂纹密度和高孔隙度为特征）与低速区（在18-30 km深度处）相吻合，如该地区的层析成像研究所描绘的那样。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号