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Pulse-Like Partial Ruptures and High-Frequency Radiation at Creeping-Locked Transition during Megathrust Earthquakes

Michel, Sylvain and Avouac, Jean-Philippe and Lapusta, Nadia and Jiang, Junle (2017) Pulse-Like Partial Ruptures and High-Frequency Radiation at Creeping-Locked Transition during Megathrust Earthquakes. Geophysical Research Letters, 44 (16). pp. 8345-8351. ISSN 0094-8276.

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Megathrust earthquakes tend to be confined to fault areas locked in the interseismic period and often rupture them only partially. For example, during the 2015 M7.8 Gorkha earthquake, Nepal, a slip pulse propagating along strike unzipped the bottom edge of the locked portion of the Main Himalayan Thrust (MHT). The lower edge of the rupture produced dominant high-frequency (>1 Hz) radiation of seismic waves. We show that similar partial ruptures occur spontaneously in a simple dynamic model of earthquake sequences. The fault is governed by standard laboratory-based rate-and-state friction with the aging law and contains one homogenous velocity-weakening (VW) region embedded in a velocity-strengthening (VS) area. Our simulations incorporate inertial wave-mediated effects during seismic ruptures (they are thus fully dynamic) and account for all phases of the seismic cycle in a self-consistent way. Earthquakes nucleate at the edge of the VW area and partial ruptures tend to stay confined within this zone of higher prestress, producing pulse-like ruptures that propagate along strike. The amplitude of the high-frequency sources is enhanced in the zone of higher, heterogeneous stress at the edge of the VW area.

Item Type:Article
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URLURL TypeDescription
Michel, Sylvain0000-0001-7878-6603
Avouac, Jean-Philippe0000-0002-3060-8442
Lapusta, Nadia0000-0001-6558-0323
Jiang, Junle0000-0002-8796-5846
Additional Information:© 2017 American Geophysical Union. Received 26 JUN 2017; Accepted 10 AUG 2017; Accepted article online 16 AUG 2017; Published online 31 AUG 2017. The data used are listed in the supporting information. We thank Yen-Yu Lin for his help with the numerical code. We thank Adriano Gualandi, James Jackson, and Alex Copley for discussions. This research was partially funded by the National Science Fundation throuh grant EAR 1345136.
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:Partial Ruptures; Pulse; High Frequency Radiation; Megathrusts; Gorkha earthquake; Main Himalayan Thrust
Record Number:CaltechAUTHORS:20170817-075028405
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Official Citation:Michel, S., J.-P. Avouac, N. Lapusta, and J. Jiang (2017), Pulse-like partial ruptures and high-frequency radiation at creeping-locked transition during megathrust earthquakes, Geophys. Res. Lett., 44, 8345–8351, doi:10.1002/2017GL074725
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:80547
Deposited By: Tony Diaz
Deposited On:17 Aug 2017 15:03
Last Modified:02 Mar 2018 21:15

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