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Near-surface seismic site characterization using Nakamura-based HVSR technique in the geological complex region of Kangra Valley, northwest Himalaya, India
Arabian Journal of Geosciences Pub Date : 2021-05-06 , DOI: 10.1007/s12517-021-07136-w
Ambrish Kumar Mahajan , Praveen Kumar , Pawan Kumar

The two major towns, Kangra and Dharamshala, located in the northwest Himalaya have been a subject of great interest for the first-level microzonation due to their high seismic hazard potential. Tectonically, the region is geologically complex and lying between two major thrusts, i.e., the Main Boundary Thrust (MBT) to the northeast and the Jawalamukhi Thrust (JMT) to the southwest. Therefore, the valley is highly deformed and fractured and has developed several small and major faults longitudinally and transversely. The Kangra town is underlain by the Upper Siwalik Boulder Conglomerates, whereas Dharamshala town by the sandstone, claystone, and mudstone with variable thickness of soft soil cover above the bedrock. These regions faced devastating damage from the 1905 Kangra earthquake (Ms 7.8). So, the ambient noise measurement has been performed using a dense network of 200 free-field stations to measure the fundamental frequency of each site. The analysis revealed a high variation in the typologies of HVSR peaks. The iso-frequency map of the study region indicated a wide variation within and on the peripheries of the basin in a frequency ranging from 0.26 to 12 Hz. Some isolated locations in the north-eastern and north-western parts of the study area also showed a dominance of the high resonance frequency component (12-20 Hz). The study further indicated the amplification factor varying from 1.67 to 7.68, reflecting the impact of impedance contrast between the soft soil and the bedrock.



中文翻译:

使用基于中村的HVSR技术在印度喜马拉雅山西北部Kangra山谷地质复杂区域中进行近地表地震现场表征

位于喜马拉雅山西北部的两个主要城镇Kangra和Dharamshala因其极高的地震危险性而引起了人们对一级微区带的极大兴趣。从构造上看,该地区地质复杂,位于两个主要推力之间,即东北的主边界推力(MBT)和西南的Jawalamukhi推力(JMT)。因此,该山谷高度变形和破裂,并在纵向和横向上形成了一些小的和主要的断层。坎格拉(Kangra)镇位于上西瓦利克(Siwalik Boulder)砾岩群之下,而达兰萨拉(Dharamshala)镇则位于砂岩,黏土和泥岩中,基岩上方的软土覆盖层厚度各异。这些地区因1905年的康拉地震(7.8女士)而遭受毁灭性破坏。所以,使用由200个自由场站组成的密集网络执行环境噪声测量,以测量每个站点的基本频率。分析显示,HVSR峰的类型差异很大。研究区域的等频图表明,盆地外围和外围的频率变化范围为0.26至12 Hz。在研究区域的东北部和西北部的一些偏僻地区,也显示出高共振频率分量(12-20 Hz)占主导地位。研究还表明,放大系数在1.67到7.68之间变化,反映了软土和基岩之间阻抗对比的影响。分析显示,HVSR峰的类型差异很大。研究区域的等频图表明,盆地外围和外围的频率变化范围为0.26至12 Hz。在研究区域的东北部和西北部的一些偏僻地区,也显示出高共振频率分量(12-20 Hz)占主导地位。研究还表明,放大系数在1.67到7.68之间变化,反映了软土和基岩之间阻抗对比的影响。分析显示,HVSR峰的类型差异很大。研究区域的等频图表明,盆地外围和外围的频率变化范围为0.26至12 Hz。在研究区域的东北部和西北部的一些偏僻地区,也显示出高共振频率分量(12-20 Hz)占主导地位。研究还表明,放大系数在1.67到7.68之间变化,反映了软土和基岩之间阻抗对比的影响。在研究区域的东北部和西北部的一些偏僻地区,也显示出高共振频率分量(12-20 Hz)占主导地位。研究还表明,放大系数在1.67到7.68之间变化,反映了软土和基岩之间阻抗对比的影响。在研究区域的东北部和西北部的一些偏僻地区,也显示出高共振频率分量(12-20 Hz)占主导地位。研究还表明,放大系数在1.67到7.68之间变化,反映了软土和基岩之间阻抗对比的影响。

更新日期:2021-05-06
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