Permanent upper plate deformation in western Myanmar during the great 1762 earthquake: Implications for neotectonic behavior of the northern Sunda megathrust

Abstract

The 1762 Arakan earthquake resulted from rupture of the northern Sunda megathrust and is one of those rare preinstrumental earthquakes for which early historical accounts document ground deformations. In order to obtain more comprehensive and detailed measurements of coseismic uplift, we conducted comprehensive field investigations and geochronological analyses of marine terraces on the two largest islands in western Myanmar. We confirm 3–4 m of coseismic coastal emergence along southwestern Cheduba Island, diminishing northeastward to less than 1 m. Farther northeast, uplift associated with the earthquake ranges from slightly more than 1 m to 5–6 m along the western coast of Ramree Island but is insignificant along the island's eastern coast. This double‐hump pattern of uplift coincides with the long‐term anticlinal growth of these two islands. Thus, we propose that the 1762 earthquake resulted from slip on splay faults under the islands, in addition to rupture of the megathrust. Elastic modeling implies that fault slip during the 1762 earthquake ranges from about 9 to 16 m beneath the islands and corresponds to a magnitude of Mw 8.5 if the rupture length of the megathrust is ~500 km. The island's uplift histories suggest recurrence intervals of such events of about 500–700 years. Additional detailed paleoseismological studies would add significant additional detail to the history of large earthquakes in this region.

The reef platform of Martinique: Interplay between eustasy, tectonic subsidence and volcanism since Late Pleistocene

“…Melnick et al, 2009;Wang et al, 2013;Pedoja et al, 2013). These results are fundamental for seismic hazard assessment and mitigation.…”

Chapter 2 Active tectonics of Myanmar and the Andaman Sea

“…However, as Steckler et al (2008) point out, major events do occur in high-sediment-input systems such as the 1964 Alaskan earthquake (Ruff 1989(Ruff , 1992, and the high geothermal gradients associated with thick sediment piles may actually promote stick-slip behaviour at relatively shallow depths. Wang et al (2013) confirmed that slip did occur on the megathrust interface on the Arakan segment beneath the offshore extension of the Ganges-Brahmaputra delta in the Bay of Bengal, suggesting this sediment-clogged system is capable of failure. The fact that slip in the Arakan earthquake appears to have been transferred from the megathrust onto imbricate faults within the accretionary prism (Wang et al 2013) supports the suggestion that severe damage was not reported in western cities such as Dhaka after the 1548 earthquake, due to a similar process (Steckler et al 2008).…”

“…Wang et al (2013) confirmed that slip did occur on the megathrust interface on the Arakan segment beneath the offshore extension of the Ganges-Brahmaputra delta in the Bay of Bengal, suggesting this sediment-clogged system is capable of failure. The fact that slip in the Arakan earthquake appears to have been transferred from the megathrust onto imbricate faults within the accretionary prism (Wang et al 2013) supports the suggestion that severe damage was not reported in western cities such as Dhaka after the 1548 earthquake, due to a similar process (Steckler et al 2008). Steckler et al (2008) suggest that this behaviour may occur because the burial of the tip of the accretionary prism beneath the sediments of the Ganges-Brahmaputra delta promoted the transfer of megathrust slip onto imbricate thrusts to thicken the deforming wedge.…”

“…This earthquake uplifted a number of islands along the Arakan coast and caused extensive damage as far north as Chittagong (Cummins 2007). Wang et al (2013) collected extensive field data for coastal uplift associated with this earthquake on Cheduba and Ramree islands. They inferred that 9-16 m of slip occurred beneath the islands corresponding to an M w 8.5 earthquake, and suggested that the repeat time of such an earthquake would be 500-700 years.…”

Reflections on recent recommendations on the use of science in disaster risk reduction using case studies from Bangladesh and the western United States

“…Particularly notable earthquakes occurred in A.D. 1762 and 1897. The A.D. 1762 Arakan earthquake occurred off the east coast of Bangladesh, which Wang et al (2013) estimated had a magnitude of ~8.5 Mw (moment magnitude). This event caused widespread heavy damage, liquefaction and landslides in the Chittagong region, and a rapid increase in the level of the river at Dhaka that drove hundreds of boats onshore and caused signifi cant loss of life (Martin and Szeliga, 2010).…”