Recent seismicity in Northeast India and its adjoining region
Recent seismicity in Northeast India and its adjoining region
复制标题
印度东北部及其毗邻地区近期地震活动
DOI：
10.1007/s10950-007-9074-y
复制
发表时间：
2008
影响因子：
1.6
通讯作者：
William K. Mohanty
中科院分区：
文献类型：
--
作者：
K. Thingbaijam;S. Nath;A. Yadav;A. Raj;M. Walling;William K. Mohanty
印度东北部及其邻近地区最近的地震活动表现出不同的地震机制-主要是东部边界的逆冲断层，喜马拉雅山上部的正断层，以及其余地区的走滑。利用国际地震中心（ISC）星表和全球质心矩张量（GCMT）数据库，得到了1906 - 2006年的矩震级（MW）均一化星表。由于从1964年以来所看到的显著和稳定的地震记录，在该地区的地震活动性进行了分析的时间与空间分布的震级完整性mt，b值，a值和相关分形维数DC。发现mtis的估计值在4.0和4.8之间变化。a值从4.47到8.59不等，b值从0.61到1.36不等。逆冲断层带主要表现出较低的b值分布，而走滑和正断层活动则表现出中等偏高的b值分布，DC值在0.70 ~ 1.66之间变化。虽然b值和DC的空间分布之间的相关性主要是负的，但在该领域的某些部分也可以观察到正相关性。一个主要的观察结果是与东部边界逆冲区域的低b值显著负相关，这意味着可能存在扩展粗糙体的情况。顺便说一句，盒计数法的研究区域的断层段的应用表明相对较高的分形维数，D，这表明在二维空间范围内的平面几何覆盖的倾向。最后，根据估计的地震空间活动模式，与底层活动断层网络合作，划定了四个广泛的地震震源区。目前的工作评价的地震活动性方案，在该国的地震省的地震危险性评估的基础工作的履行。
Recent seismicity in the northeast India and its adjoining region exhibits different earthquake mechanisms – predominantly thrust faulting on the eastern boundary, normal faulting in the upper Himalaya, and strike slip in the remaining areas. A homogenized catalogue in moment magnitude,MW, covering a period from 1906 to 2006 is derived from International Seismological Center (ISC) catalogue, and Global Centroid Moment Tensor (GCMT) database. Owing to significant and stable earthquake recordings as seen from 1964 onwards, the seismicity in the region is analyzed for the period with spatial distribution of magnitude of completenessmt,bvalue,avalue, and correlation fractal dimensionDC. The estimated value ofmtis found to vary between 4.0 and 4.8. Theavalue is seen to vary from 4.47 to 8.59 whilebvalue ranges from 0.61 to 1.36. Thrust zones are seen to exhibit predominantly lowerbvalue distribution while strike-slip and normal faulting regimes are associated with moderate to higherbvalue distribution.DCis found to vary from 0.70 to 1.66. Although the correlation between spatial distribution ofbvalue andDCis seen predominantly negative, positive correlations can also be observed in some parts of this territory. A major observation is the strikingly negative correlation with lowbvalue in the eastern boundary thrust region implying a possible case of extending asperity. Incidentally, application of box counting method on fault segments of the study region indicates comparatively higher fractal dimension,D, suggesting an inclination towards a planar geometrical coverage in the 2D spatial extent. Finally, four broad seismic source zones are demarcated based on the estimated spatial seismicity patterns in collaboration with the underlying active fault networks. The present work appraises the seismicity scenario in fulfillment of a basic groundwork for seismic hazard assessment in this earthquake province of the country.