摘要
This study investigates the spatial and temporal variation of fractal dimension and b-value for the eastern part of the Himalaya and adjoining area(26°N–31°N and 87°E–98°E).The analysis is carried out on the earthquake dataset of 1373 events(Mc=4.0)by sliding window technique for the period 1964 to 2020.The region is divided into three sub regions A(87°E–92°E),B(92°E–94°E)and C(94°E–98°E).The b-value computed for the region A comprising eastern Nepal is smaller compared to other two regions which infers the possible high stress and asperities in the region.High spatial fractal dimension(Dc>1.5)and low temporal fractal dimension(Dt<0.31)are computed for the regions.High spatial fractal dimension may indicate that fractures generating earthquakes are approaching a 2D structure and low temporal fractal dimension implies high clustering of earthquake’s epicenters.The b value shows a weak negative correlation with Dc for regions A and C while a weak positive correlation is observed for the region B.Based on b-value and fractal dimension,this study explains the frequency of earthquakes and heterogeneity of the seismogenic structure in this part of the Himalaya.
基于1964—2020年1373次地震(Mc=4.0),采用滑动窗口方法对喜马拉雅山脉东段及其周边地区(26°N–31°N和87°E–98°E)地震b值和分形维数时空特征进行分析。论文将研究区划分为3个子区,即A区(87°E–92°E),B区(92°E–94°E)和C区(94°E–98°E)。在A区包括尼泊尔东部,b值要高于其他区域,说明该区域可能存在高应力集聚和凹凸体。同时,A区地震具有高空间(Dc>1.5)和低时间分形维数(Dt<0.31),说明地震孕育断层接近于2维结构,且震中具有群聚群发特征。A区、C区地震b值与空间分形维度弱负相关,两者在B区则呈弱正相关。基于b值和分形维数,论文解释了喜马拉雅山脉东段孕震结构的时空变化的特征,可为理解区域强震发生规律提供理论基础。
基金
University Grants Commission(UGC),Nepal for providing financial support。
