Active Convergence of the India‐Burma‐Sunda Plates Revealed by a New Continuous GPS Network. Issue 3 (25th March 2019)

• Record Type: Journal Article
• Authors: Mallick, Rishav; Lindsey, Eric O.; Feng, Lujia; Hubbard, Judith; Banerjee, Paramesh; Hill, Emma M.
• Is Part Of: Journal of geophysical research. Volume 124:Issue 3(2019)
• Page Start: 3155
• Page End: 3171
• Publication Date: 2019-03-25
• Subjects: oblique convergence -- India‐Burma convergence -- strain partitioning -- Rakhine Bangladesh megathrust -- Churachandpur Mao (CMF) -- Sagaing Fault; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2018JB016480
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The Rakhine (Arakan)‐Bangladesh megathrust, along which the Indian and Burma plates collide, is assumed by some to be inactive/aseismic due to the lack of notable interplate earthquakes in the modern instrumental catalog. However, geological and historical evidence of the great 1762 Arakan earthquake suggest the megathrust can produce M ~8 events that could adversely affect the lives of millions of people in the region. To investigate the seismogenic potential and determine the slip budget of the megathrust, we first need to solve for India‐Burma‐Sunda relative plate motions. We present a new set of 24 GPS velocities (2011–2017) from the Myanmar‐India‐Bangladesh‐Bhutan continuous GPS network. We use the new velocities and those from previously published studies to explore the geometries and slip rates of three major faults (Rakhine‐Bangladesh megathrust, Churachandpur‐Mao Fault, and Sagaing Fault) that accommodate the India‐Burma‐Sunda plate motion. Our results suggest that the three major faults we studied are likely fully coupled; the modern shortening rate across the Burma plate is 12–24 mm/year, while the total dextral shear rate is 25–32 mm/year. The possibly fully coupled shallow megathrust, and splay faults that may sole into it, are geodetically invisible while they are not slipping. However, we can identify the transition from coupling to steady creep on the deeper extension of the megathrust; we use this to show active oblique India‐Burma convergence and to map along‐strike and along‐dip variations in dip‐slip and strike‐slip motion. This implies that the megathrust is currently accumulating strain which will eventually be released in earthquakes. Key Points: We demonstrate active convergence between India and Burma using 2‐D and 3‐D plate motion models The Rakhine‐Bangladesh megathrust is the most likely candidate to accommodate ~18 mm/year of India‐Burma convergence Strain partitioning is necessary within the Indo‐Burman Wedge, and we can place an upper bound of 8 mm/year on the slip rate of the Churachandpur‐Mao Fault