Active tectonics and earthquake potential of the Myanmar region

Abstract

This paper describes geomorphologic evidence for the principal neotectonic features of Myanmar and its immediate surroundings. We combine this evidence with published structural, geodetic, and seismic data to present an overview of the active tectonic architecture of the region and its seismic potential. Three tectonic systems accommodate oblique collision of the Indian plate with Southeast Asia and extrusion of Asian territory around the eastern syntaxis of the Himalayan mountain range. Subduction and collision associated with the Sunda megathrust beneath and within the Indoburman range and Naga Hills accommodate most of the shortening across the transpressional plate boundary. The Sagaing fault system is the predominant locus of dextral motion associated with the northward translation of India. Left-lateral faults of the northern Shan Plateau, northern Laos, Thailand, and southern China facilitate extrusion of rocks around the eastern syntaxis of the Himalaya. All of these systems have produced major earthquakes within recorded history and continue to present major seismic hazards in the region.

Chapter 2 Active tectonics of Myanmar and the Andaman Sea

“…The >200 km long section running between the second and third largest cities in Myanmar, Mandalay and the new capital Naypyitaw has no clear instrumental or historical record of rupture. Wang et al (2014) suggest that a large earthquake in 1839 may have ruptured all or part of this section, although this has not been confirmed. The lack of a record of large earthquakes on this segment suggests that it is either slipping aseismically, or that it fails in large earthquakes and has been accumulating elastic strain for some time.…”

“…2.2). Wang et al (2014) did not find convincing evidence of recent rupture on the southern boundary of the Naga Hills, and there is little recent instrumental evidence for significant thrusting on this boundary. The International Seismological Centre (ISC) reports two major earthquakes in this area in 1906 and 1908 (M s 7.0 and 7.5, respectively).…”

“…2.2; Le Dain et al 1984). Eyewitness reports stated that the 1858 earthquake caused flow in the Irrawaddy to reverse in this region (Oldham 1883), and Wang et al (2014) suggest that this may be because the earthquake uplifted an anticline that crosses the river in this area. Again this earthquake emphasizes the possibility of large events occurring away from the Sagaing Fault, in this case on a blind thrust beneath the anticline.…”

Chapter 1 Introduction to the Petroleum Geology of Myanmar

“…The crustal reaction to that oblique convergence has been widespread earthquakes which are related to: (1) the subduction of the India Plate beneath the Burma Platelet (although Rangin et al (2013) argue that the western boundary of the Burma Platelet north of the Andaman Islands has not been subducted since the Mesozoic, the seismicity in that northern zone therefore resulting from ongoing detachment and sinking of an old slab); (2) right-lateral movement on mostly N -S or NW -SE wrench faults with accompanying thrusting; and (3) left-lateral movement on wrench faults with WSW -ENE trends, caused by the clockwise flow of the lithosphere as it is displaced under gravity from beneath the eastern Himalaya syntaxis. A study of the neotectonics of Myanmar has been carried out by Wang et al (2014) from satellite imagery and fieldwork, and their simplified map is provided in Figure 1.6.…”

On the Holocene Evolution of the Ayeyawady Megadelta

“…Given the 511 high seismicity of the region (Wang et al, 2014), large earthquakes (Aung et al, 2008) 512 may have also played a role in the avulsion. 513 514…”