Locked crustal faults associated with the subducting Indian Lithosphere and its implications in seismotectonic activity in the Central Indo-Burmese Ranges, Northeast India

IF 0.9 4区 地球科学 Q4 GEOCHEMISTRY & GEOPHYSICS
Geofizika Pub Date : 2022-03-31 DOI:10.15233/gfz.2022.39.5
Raghupratim Rakshit, D. Bezbaruah, Farha Zaman, Bubul Bharali, Sowrav Saikia
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引用次数: 1

Abstract

Northeast India is a geodynamic hotspot for tectonic activities where three different plates viz., Indian, Eurasian and Burma Plates collide and deform with respect to each other. Northeast moving Indian Plate subducting transversely beneath Burma Plate results in the formation of the Indo-Burmese Ranges (IBR). In central IBR, the north-south trending Churachandpur-Mao Fault (CMF) is situated in the east of the Mizoram-Tripura Fold belt. The northwest-southeast trending Mat River Fault or Mat Fault (MF), which is another major crustal-scale strike-slip transverse fault, upholds the movement of the CMF. In this work, seismotectonic analysis of these two active intra-plate faults which are related to the June-September 2020 earthquake series, have been discussed. It is observed from satellite imageries, earthquake data and confirmed by the field investigation that these faults are not directly involved in the generation of the earthquakes; rather epicenters are distributed in the junction between the MF and CMF. It is evident from the seismotectonic analysis that this stress is distributed through some northwest-southeast synthetic faults, located north of MF and parallel to it, close to the junction with the CMF. The focal solution of the strongest of the 2020 earthquakes, the 5.5 Mw Champhai earthquake (on 22nd June 2020 at 04:10 IST) in Mizoram shows that the principal nodal plane was aligning along MF. Therefore, it is these synthetic faults that are responsible for the earthquakes rather than the locked zone between intra-plate MF and CMF crustal faults. This juxtaposition has caused a major shift in the geodynamic regime in the central IBR. Champhai earthquake might not be the only large devastating earthquake in the region and could be followed by more major earthquakes in the future.
印度东北部印度-缅甸山脉中部与俯冲印度岩石圈有关的锁定地壳断层及其在地震构造活动中的意义
印度东北部是构造活动的地球动力学热点,三个不同的板块即印度板块、欧亚板块和缅甸板块相互碰撞和变形。印度板块向东北移动,横向俯冲于缅甸板块之下,形成了印缅山脉。西北-东南走向的席河断裂或席河断裂(MF)是另一条重要的地壳尺度走滑横向断裂,支撑着CMF的运动。本文对这两条与2020年6 - 9月地震系列有关的活动板内断裂进行了地震构造分析。从卫星图像、地震资料和实地考察证实,这些断裂与地震的发生没有直接关系;相反,震中分布在中频和CMF之间的交界处。从地震构造分析中可以明显看出,该应力分布在一些西北-东南方向的合成断裂中,这些断裂位于中频以北并与中频平行,靠近中频连接处。2020年最强地震,5.5 Mw Champhai地震(2020年6月22日04:10 IST)在米佐拉姆邦的震源解显示主节点平面沿中频排列。因此,这些合成断裂是造成地震的原因,而不是板块内中频和中频地壳断裂之间的锁定带。这种并置导致了IBR中部地球动力学体系的重大转变。香槟地震可能不是该地区唯一的破坏性大地震,未来可能会发生更多的大地震。
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来源期刊
Geofizika
Geofizika 地学-地球化学与地球物理
CiteScore
1.60
自引率
0.00%
发文量
17
审稿时长
>12 weeks
期刊介绍: The Geofizika journal succeeds the Papers series (Radovi), which has been published since 1923 at the Geophysical Institute in Zagreb (current the Department of Geophysics, Faculty of Science, University of Zagreb). Geofizika publishes contributions dealing with physics of the atmosphere, the sea and the Earth''s interior.
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