Observational Evidence of the Early and Persistent Supershear Rupture of the 2018 Mw 7.5 Palu Earthquake
Date: 4/25/2019
Time: 01:45 PM
Room: Cascade I
The speed at which an earthquake rupture propagates affects its energy balance and ground shaking impact. Supershear earthquakes (faster than shear-wave speed Vs) often start at sub-shear speed and later run faster than Eshelby’s speed (√2Vs). Here we present robust evidence of early and persistent supershear rupture at sub-Eshelby speed of the 2018 Mw 7.5 Palu, Indonesia earthquake. Slowness-enhanced back-projection of teleseismic data provides a sharp image of the rupture process, along a path consistent with the surface rupture trace inferred by sub-pixel correlation of interferometric synthetic-aperture radar images. The rupture propagated at a sustained velocity of 4.1 km/s from its initiation to its end, despite large fault bends. The persistent supershear speed is further validated by seismological evidence of far-field Rayleigh Mach waves. The unusual features of this earthquake may reveal connections between rupture dynamics and fault structure. Early supershear transition can be promoted by fault roughness near the hypocenter. Steady rupture propagation at a speed unexpected in homogeneous media could result from the presence of a damaged fault zone.
Presenting Author: Han Bao
Authors
Han Bao hbrandon@ucla.edu University of California, Los Angeles, Los Angeles, California, United States Presenting Author
Corresponding Author
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Jean-Paul Ampuero ampuero@gps.caltech.edu California Institute of Technology, Pasadena, California, United States |
Lingsen Meng meng@epss.ucla.edu University of California, Los Angeles, Los Angeles, California, United States |
Eric J Fielding eric.j.fielding@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States |
Cunren Liang cunrenl@caltech.edu California Institute of Technology, Seismological Laboratory, Pasadena, California, United States |
Christopher W D Milliner christopher.milliner@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States |
Tian Feng tianfengseis@ucla.edu University of California, Los Angeles, Los Angeles, California, United States |
Hui Huang oldyellow9451@gmail.com University of California, Los Angeles, Los Angeles, California, United States |
Observational Evidence of the Early and Persistent Supershear Rupture of the 2018 Mw 7.5 Palu Earthquake
Category
Earthquake Source Parameters: Theory, Observations and Interpretations