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Two‐stage composite megathrust rupture of the 2015 M w 8.4 Illapel, Chile, earthquake identified by spectral‐element inversion of teleseismic waves
Author(s) -
Lee ShiannJong,
Yeh TeYang,
Lin TzuChi,
Lin YenYu,
Song TehRu Alex,
Huang BorShouh
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068843
Subject(s) - seismology , subduction , geology , hypocenter , trench , interplate earthquake , slip (aerodynamics) , episodic tremor and slip , moment magnitude scale , tsunami earthquake , inversion (geology) , intraplate earthquake , tectonics , induced seismicity , geometry , physics , chemistry , mathematics , organic chemistry , layer (electronics) , scaling , thermodynamics
The M w 8.4 Illapel earthquake occurred on 16 September was the largest global event in 2015. This earthquake was not unexpected because the hypocenter was located in a seismic gap of the Peru‐Chile subduction zone. However, the source model derived from 3‐D spectral‐element inversion of teleseismic waves reveals a distinct two‐stage rupture process with completely different slip characteristics as a composite megathrust event. The two stages were temporally separated. Rupture in the first stage, with a moment magnitude of M w 8.32, built up energetically from the deeper locked zone and propagated in the updip direction toward the trench. Subsequently, the rupture of the second stage, with a magnitude of M w 8.08, mainly occurred in the shallow subduction zone with atypical repeating slip behavior. The unique spatial‐temporal rupture evolution presented in this source model is key to further in‐depth studies of earthquake physics and source dynamics in subduction systems.