Open AccessDepth‐varying rupture properties of subduction zone megathrust faults
Author(s) -
Lay Thorne,
Kanamori Hiroo,
Ammon Charles J.,
Koper Keith D.,
Hutko Alexander R.,
Ye Lingling,
Yue Han,
Rushing Teresa M.
Publication year - 2012
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jb009133
Subject(s) - subduction , geology , seismology , lithosphere , fault (geology) , trench , convergent boundary , episodic tremor and slip , period (music) , plate tectonics , tectonics , oceanic crust , layer (electronics) , chemistry , physics , organic chemistry , acoustics
Subduction zone plate boundary megathrust faults accommodate relative plate motions with spatially varying sliding behavior. The 2004 Sumatra‐Andaman (M w 9.2), 2010 Chile (M w 8.8), and 2011 Tohoku (M w 9.0) great earthquakes had similar depth variations in seismic wave radiation across their wide rupture zones – coherent teleseismic short‐period radiation preferentially emanated from the deeper portion of the megathrusts whereas the largest fault displacements occurred at shallower depths but produced relatively little coherent short‐period radiation. We represent these and other depth‐varying seismic characteristics with four distinct failure domains extending along the megathrust from the trench to the downdip edge of the seismogenic zone. We designate the portion of the megathrust less than 15 km below the ocean surface as domain A, the region of tsunami earthquakes. From 15 to ∼35 km deep, large earthquake displacements occur over large‐scale regions with only modest coherent short‐period radiation, in what we designate as domain B. Rupture of smaller isolated megathrust patches dominate in domain C, which extends from ∼35 to 55 km deep. These isolated patches produce bursts of coherent short‐period energy both in great ruptures and in smaller, sometimes repeating, moderate‐size events. For the 2011 Tohoku earthquake, the sites of coherent teleseismic short‐period radiation are close to areas where local strong ground motions originated. Domain D, found at depths of 30–45 km in subduction zones where relatively young oceanic lithosphere is being underthrust with shallow plate dip, is represented by the occurrence of low‐frequency earthquakes, seismic tremor, and slow slip events in a transition zone to stable sliding or ductile flow below the seismogenic zone.