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TitleEnergy-to-moment ratios for damaging intraslab earthquakes: preliminary results on a few case studies
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AuthorOkal, E A; Kirby, S H
SourceThe Cascadia subduction zone and related subduction systems - seismic structure, intraslab earthquakes and processes, and earthquake hazards; by Kirby, S (ed.); Wang, K (ed.); Dunlop, S (ed.); Geological Survey of Canada, Open File 4350, 2002 p. 117-121, https://doi.org/10.4095/222535 (Open Access)
LinksOnline - En ligne
Year2002
Alt SeriesUnited States Geological Survey, Open-file Report 02-328
PublisherNatural Resources Canada
MeetingIntraslab Earthquakes in the Cascadia Subduction System: Science and Hazards; Victoria; CA; September 18-21, 2000
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Kirby, S; Wang, K; Dunlop, S; (2002). The Cascadia subduction zone and related subduction systems - seismic structure, intraslab earthquakes and processes, and earthquake hazards, Geological Survey of Canada, Open File 4350
File formatpdf
AreaChile
Lat/Long WENS -74.0000 -70.0000 -26.0000 -38.0000
Lat/Long WENS-105.0000 -92.0000 -12.0000 -22.0000
Subjectstectonics; geophysics; subduction zones; plate tectonics; tectonic elements; tectonic environments; tectonic interpretations; plate motions; subduction; lithosphere; oceanic lithosphere; earthquake mechanisms; seismicity; seismic energy; stress analyses; geological hazards; intraslab earthquakes
Illustrationssketch maps; plots; wave graphs
Released2002 06 11; 2016 08 31
AbstractWe use the energy-to-moment ratio, as introduced by Newman and Okal [1998] to examine the source characteristics of normal-faulting intraslab earthquakes, compared to nearby interplate thrust events, based on recent case studies in central Chile and southeastern Mexico. In Chile, we find that the 1997 intraslab event had an exceptionally large E/M0 ratio, 30 times greater than the nearby interplate shock. This suggests a very fast strain release at the source as the origin of the particularly destructive character of intraslab events. While the difference is less sharp in Mexico, we find a similar trend, which is in agreement with the observation that the locally most damaging earthquakes are indeed the intraslab events. We also document on the 1939 Chilean earthquake the feasibility of extending this approach to historical earthquakes for which high-quality analog records have been archived.
GEOSCAN ID222535