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TitleThe radiated seismic energy and apparent stress of interplate and intraslab earthquakes at subduction-zone environments: implications for seismic hazard estimation
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorChoy, G L; Boatwright, J L; 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, KORCID logo (ed.); Dunlop, S (ed.); Geological Survey of Canada, Open File 4350, 2002 p. 107-114, Open Access logo Open Access
LinksOnline - En ligne
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
Mediaon-line; digital
RelatedThis publication is contained in The Cascadia subduction zone and related subduction systems - seismic structure, intraslab earthquakes and processes, and earthquake hazards
File formatpdf
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; tsunami; geological hazards; intraslab earthquakes
Illustrationssketch maps; graphs; tables
Released2002 06 11; 2016 08 31
AbstractThe radiated seismic energies (Es) of 980 shallow subduction-zone earthquakes with magnitudes (equal or greater than) 5.8 are used to examine global patterns of energy release and apparent stress. In contrast to traditional methods which have relied upon empirical formulas, these energies are computed through direct spectral analysis of broadband seismic waveforms. Energy gives a physically different measure of earthquake size than moment. Moment, being derived from the low-frequency asymptote of the displacement spectra, is a measure of the final static displacement. Thus, moment is related to the long-term tectonic implication of an earthquake. In contrast, energy, being derived from the velocity power spectra, is more a measure of seismic potential for damage to anthropogenic structures. There is considerable scatter in the plot of Es-M0 for worldwide earthquakes. For any given M0, the Es can vary by as much as an order of magnitude about the mean regression line. The global variation between Es and M0, while large, is not random. When subsets of Es-M0 are plotted as a function of seismic region, tectonic setting and faulting type, the scatter in data is often substantially reduced. There are two profound implications for the estimation of seismic and tsunamic hazard. First, it is now feasible to characterize the apparent stress for particular regions. Second, a given M0 does not have a unique Es. This means that M0 alone is not sufficient to describe all aspects of an earthquake. In particular, we have found examples of interplate thrust-faulting earthquakes and intraslab normal-faulting earthquakes occurring in the same epicentral region with vastly different macroseismic effects. Despite the gross macroseismic disparities, the MW's in these examples were identical. However, the Me's (energy magnitudes) successfully distinguished the earthquakes that were more damaging.

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