Quaternary International ( IF 2.2 ) Pub Date : 2021-01-07 , DOI: 10.1016/j.quaint.2020.12.035 K. Silpa , Anil Earnest
Kinematic source process models using tele-seismic waveform inversion of three stable continental region (SCR) earthquakes from India (1993 Mw 6.2 Latur, 1997 Mw 5.8 Jabalpur and 2001 Mw 7.6 Bhuj) are presented in this paper to demonstrate the slip evolution and stress drop. These finite-fault models are methodologically unique to constrain the source dimensions, compared with assumptions and quasi-observations around blind faults. Our results show that these events do have a compact zone of singular asperity breakage within the Indian crust. Whereas the Bhuj and Jabalpur events have their rupture majorly restricted within the lower crustal regions. The Latur event ruptured a very shallow crustal asperity. The estimated rupture velocities are in the range of 2.6–3.2 km/s, Bhuj event the slowest and lengthiest. Our results do not favour an updip shallow component of asperity breakage for the Bhuj earthquake, as evident from lack of surface ruptures. Study also indicates that the 1993 Latur event occurred on a fault with high stress concentration which indicates stronger fault asperities or slip within a newer fault. Models on 1997 Jabalpur event imply higher frictional strength and very brittle nature at the lower crustal regions of the Indian slab, indicating a mechanically very strong lower crust. We conclude that an event like Latur can occur anywhere within continental interiors of Indian SCR, or elsewhere globally, and is an underestimated seismic hazard.
中文翻译:
重新审视稳定的大陆内部的地震发生特征:三个印度事件的案例
本文介绍了使用远程地震波形反演的三个稳定印度大陆地震(SCR)的运动源过程模型(1993 Mw 6.2 Latur,1997 Mw 5.8 Jabalpur和2001 Mw 7.6 Bhuj),以证明滑动演化和应力降。与围绕盲断层的假设和准观测相比,这些有限断层模型在方法上是唯一的,可以约束震源的尺寸。我们的结果表明,这些事件确实在印度地壳内有一个紧凑的单一凹凸不平断裂带。普吉和贾巴尔普尔事件的破裂主要局限于低地壳区域。拉图尔事件破坏了一个非常浅的地壳。估计的破裂速度在2.6-3.2 km / s的范围内,Bhuj事件是最慢和最长的。我们的研究结果不支持普吉地震粗糙破裂的浅层上升,这是由于缺乏地表破裂所证明的。研究还表明,1993年的Latur事件发生在高应力集中的断层上,这表明较强的断层凹凸或较新断层的滑动。1997年Jabalpur事件的模型表明,印度板块下部地壳区域具有较高的摩擦强度和非常脆的性质,表明其下地壳在机械上非常坚固。我们得出的结论是,类似Latur的事件可能发生在印度SCR大陆内部的任何地方或全球其他地方,并且被低估了地震危险。研究还表明,1993年的Latur事件发生在高应力集中的断层上,这表明较强的断层凹凸或较新断层的滑动。1997年Jabalpur事件的模型表明,印度板块下部地壳区域具有较高的摩擦强度和非常脆的性质,表明其下地壳在机械上非常坚固。我们得出的结论是,类似Latur的事件可能发生在印度SCR大陆内部的任何地方或全球其他地方,并且被低估了地震危险。研究还表明,1993年的Latur事件发生在高应力集中的断层上,这表明较强的断层凹凸或较新断层的滑动。1997年Jabalpur事件的模型表明,印度板块下部地壳区域具有较高的摩擦强度和非常脆的性质,表明其下地壳在机械上非常坚固。我们得出的结论是,类似Latur的事件可能发生在印度SCR大陆内部的任何地方或全球其他地方,并且被低估了地震危险。