Upper-plate splay fault earthquakes along the Arakan subduction belt recorded by uplifted coral microatolls on northern Ramree Island, western Myanmar (Burma)
Journal
Earth and Planetary Science Letters
Journal Volume
484
Pages
241-252
Date Issued
2018
Author(s)
Wang, Chung-Che
Chiang, Hong-Wei
Liu, Sze-Chieh
Min, Soe
Aung, Lin Thu
Than, Oo
Tun, Soe Thura
Abstract
Upper-plate structures that splay out from the megathrusts are common features along major convergent plate boundaries. However, their earthquake and tsunami hazard potentials have not yet received significant attention. In this study, we identified at least one earthquake event that may have been produced by an upper-plate splay fault offshore western Myanmar, based on U–Th ages of uplifted coral microatolls. This event is likely an earthquake that was documented historically in C.E. 1848, with an estimated magnitude between 6.8 and 7.2 based on regional structural characteristics. Such magnitude is consistent with the observed co-seismic uplift amount of ∼0.5 m. Although these events are smaller in magnitude than events produced by megathrusts, they may produce higher earthquake and tsunami hazards for local coastal communities due to their proximity. Our results also indicate that earthquake events with co-seismic uplift along the coast may not necessarily produce a flight of marine terraces. Therefore, using only records of uplifted marine terraces as megathrust earthquake proxies may overlook the importance of upper-plate splay fault ruptures, and underestimate the overall earthquake frequency for future seismic and tsunami hazards along major subduction zones of the world. © 2017 Elsevier B.V.
Other Subjects
Earthquake effects; Faulting; Geophysics; Hazards; Plates (structural components); Seismology; Structural geology; Tsunamis; Coastal uplift; coral microatolls; Myanmars; Ramree Island; Upper plate; Earthquakes; atoll; coastal zone; earthquake event; earthquake magnitude; fault; seismic hazard; subduction zone; thorium; uplift; uranium series dating; Myanmar; Ramree Island; Anthozoa
Type
journal article