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| Titel |
Estimating maximum magnitude in the presence of varying magnitude of completeness: The M9 Tohoku earthquake |
| VerfasserIn |
Gert Zöller, Matthias Holschneider, Sebastian Hainzl |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074087
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| Zusammenfassung |
| The technique to estimate the maximum magnitude in a time window of length T as
introduced by Zöller et al. (BSSA 103, 2013) is extended for earthquake catalogs with
varying magnitude of completeness. In particular, we consider the case that two types of
catalogs are available: a historic catalog and an instrumental catalog. This leads to competing
interests with respect to the estimation of the two parameters from the Gutenberg-Richter law,
namely the b-value and the event rate Î (or the a-value): the b value is estimated most
precisely from the frequently occurring small earthquakes; the tendency of small events to
cluster in aftershocks, swarms, etc. violates, however, the assumption of a Poisson
process that is used for the estimation of Î. We suggest to address this conflict by
replacing the Bayesian estimation of b by a point estimate Ëb inferred from instrumental
seismicity and use large magnitude events for the remainder of the study. Applying
the method to Japan, we find that with a credibility level of 50% the maximum
magnitude for a time interval of T = 50 years is Mmax = 9.0. The results indicate
that in the light of the available earthquake catalogs, the size of the M9 Tohoku
earthquake in 2011 is not at all a surprise. Finally, for typical scenarios related to
requirements of nuclear safety, the maximum expected magnitude will be even higher. |
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