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Rupture‐Depth‐Varying Seismicity Patterns for Major and Great ( M w ≥ 7.0) Megathrust Earthquakes
Author(s) -
Wetzler Nadav,
Lay Thorne,
Brodsky Emily E.,
Kanamori Hiroo
Publication year - 2017
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 - 10.1002/2017gl074573
Subject(s) - intraplate earthquake , seismology , geology , aftershock , interplate earthquake , subduction , induced seismicity , trench , asperity (geotechnical engineering) , plate tectonics , tectonics , geotechnical engineering , chemistry , organic chemistry , layer (electronics)
Large earthquakes on subduction zone plate boundary megathrusts result from intervals of strain accumulation and release. The mechanism diversity and spatial distribution of moderate‐size aftershocks is influenced by the mainshock rupture depth extent. Mainshocks that rupture across the shallow megathrust to near the trench have greater intraplate aftershock faulting diversity than events with rupture confined to deeper portions of the megathrust. Diversity of intraplate aftershock faulting also increases as the size of the mainshock approaches the largest size event to have ruptured that region of the megathrust. Based on these tendencies, we identify “breakthrough” ruptures as those involving shallow rupture of the megathrust with volumetrically extensive elastic strain drop around the plate boundary that allows activation of diverse intraplate faulting influenced by long‐term ambient deformation stresses. In contrast, homogeneity of the aftershock faulting mechanisms indicates only partial release of elastic strain energy and remaining potential for another large rupture.