Slip partitioning and plate kinematic barriers to megathrust rupture

Kyle Bradley, Wardah Shafiqah Binti Mohammad Fadil, & Shengji Wei

Published August 15, 2019, SCEC Contribution #9691, 2019 SCEC Annual Meeting Poster #186

Great earthquakes arise from horizontal propagation of fault ruptures over distances approaching the length of Earth’s minor tectonic plates. At these scales, the rotational relative motion of rigid plates dictates the rate and direction in which elastic strain is accumulated and released on megathrust faults. This situation is particularly well developed along the convergent margin running from Myanmar to Java, Indonesia, where both the overriding and underthrusting lithosphere contacting the megathrust are disrupted by major fault systems. There, upper plate strike-slip faults and oceanic spreading ridges define elongate forearc sliver plates that move independently above the subducted slab, while lower plate strike-slip faults that extend beneath the forearc accommodate relative convergence between India and Australia. At these fault junctions, relative plate motion produces abrupt lateral changes in the kinematics of interseismic loading on the megathrust, which are most clearly revealed by step-like changes in megathrust earthquake slip vector azimuths. We suggest that these kinematic incompatibilities may themselves impede lateral propagation of megathrust ruptures. We show that a simple geodetically constrained kinematic block model, which reconciles many first-order geological features of this complex convergent margin, also appears to explain important aspects of the rupture dynamics and lateral terminations of great subduction earthquakes.

Key Words
subduction, megathrust, rupture, barrier

Citation
Bradley, K., Shafiqah Binti Mohammad Fadil , W., & Wei, S. (2019, 08). Slip partitioning and plate kinematic barriers to megathrust rupture. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)