Modelling the seismic potential of the Indo-Burman megathrust

Abstract

The Indo-Burman arc is the boundary between the India and Burma plates, north of the Sumatra–Andaman subduction zone. The existence of active subduction in the Indo-Burman arc is a debatable issue because the Indian plate converges very obliquely beneath the Burma plate. Recent GPS measurements in Bangladesh, Myanmar, and northeast India indicate 13–17 mm/y of plate convergence along a shallow dipping megathrust while most of the strike-slip motion occurs on several steep faults, consistent with patterns of strain partitioning at subduction zones. A short period of instrumentally recorded seismicity and sparse historical records are insufficient to assess the possibility of great earthquakes at the Indo-Burman megathrust. Using the advantage of the Block-and-Fault Dynamics model allowing simultaneous simulation of slow tectonic motions and earthquakes, we test the hypothesis whether the India-Burma detachment is locked and able to produce great earthquakes, or it slips aseismically? We have shown that the model of locked detachment is preferred because it more adequately reproduces observed tectonic velocities. The integral characteristics of synthetic seismicity, the earthquake size distribution, and the rate of seismic activity are consistent with those derived from observations. Our results suggest that the megathrust is locked and can generate great M8+ earthquakes. The estimated average return period of great events exceeds one thousand years. Earthquakes of this size pose a great threat to NE India, Bangladesh and Myanmar, the most densely populated areas of the world.

On mitigation of earthquake and landslide hazards in the eastern Himalayan region

“…The Indo-Burmese megathrust is associated with the Indo-Burma Subduction beneath the Indo-Burma range. The recent studies by Steckler et al (2016) and Vorobieva et al (2021) suggest that this mega thrust is locked and may produce a great earthquake (M > 8.0), which may affect the adjoining regions, including the study area (EH).…”

Numerical Modelling of Lithospheric Block-and-Fault Dynamics: What Did We Learn About Large Earthquake Occurrences and Their Frequency?

“…Meanwhile, only models of type-III dealing with fault dynamics allow for simulating realistic earthquakes (Ismail-Zadeh et al, 2018). For example, several models were developed in the case of a large heterogeneous fault (e.g., Ben-Zion and Rice 1993;Lyakhovsky et al 2001;Zöller et al 2005;Lapusta and Liu 2009;Nodal and Lapusta 2010) and in the case of a system of faults (e.g., Gabrielov et al 1990Gabrielov et al , 2007Ward 1992Ward , 1996Ward , 2000Benites 1996, 2001;Panza et al 1997;Fitzenz and Miller 2001;Soloviev and Ismail-Zadeh 2003;Rundle et al 2006;Zhou et al 2006;, 2012aPeresan et al 2007;Zöller and Hainzl 2007;Pollitz 2009;Bielak et al 2010;Vorobieva et al 2014Vorobieva et al , 2019Vorobieva et al , 2021. The results of the modelling improved significantly our understanding of earthquake occurrences and seismic hazards.…”

“…The BAFD model was applied to study seismicity and statistics of earthquakes in several earthquake-prone areas, such as the south-eastern Carpathians (Panza et al 1997;Soloviev et al 1999;Ismail-Zadeh et al 1999), the central Alpine-Himalayan belt (Sobolev et al 1999), the western Alps (Vorobieva et al 2000;Soloviev and Ismail-Zadeh 2003), Sunda island arc (Soloviev and Ismail-Zadeh 2003), Tibet-Himalaya (Ismail-Zadeh et al 2007;Vorobieva et al 2017Vorobieva et al , 2021, Italy and its surroundings (Peresan et al 2007), Kachchh rift zone (Vorobieva et al 2014), and Caucasus (Soloviev and Gorshkov 2017;Vorobieva et al 2019). Here, we overview the application of the BAFD model to the orogenic regions, such as Carpathians, Caucasus, and Tibet-Himalaya, as well as to the Sunda arc, associated with the Indo-Australian plate subduction, which have been subjects to earlier surveys (Soloviev and Ismail-Zadeh 2003;Ismail-Zadeh et al 2012a, b;Ismail-Zadeh et al 2018).…”

Identifying Potential Earthquake Sources in Continental Environments

“…The block-and-fault dynamics modeling of the Himalayan frontal arc (Vorobieva et al 2017) has shown maximum earthquake hazard for the central Himalayan GAP area while minimum hazard has been modeled for the Bhutan Himalaya. Modeling the seismicity of the Indo-Burma arc has shown a high seismic potential in this region of India, where great M8 + earthquakes can occur (Vorobieva et al 2021).…”