Authors / CoAuthors
de Kool, M. | Jepsen,D. | Purss, M.
Abstract
The Mwp method provides a rapid estimate of the moment magnitude of an earthquake based on the P-wave arrival. In this paper we present a variation of this method that addresses two problems that are encountered when applying this method in practice. The first is that the magnitude of very large earthquakes that could generate an ocean wide tsunami is generally underestimated. The second is that the method relies on the magnitude of the first significant maximum after the P-arrival in the integrated displacement (ID) seismogram. Identification of the "correct" first maximum generally has to be performed by an analyst, which introduces a subjective step in the algorithm. In this paper we present a variation of the Mwp method that estimates the asymptotic value of the ID caused by the P arrival, rather than the first maximum. Since asymptotic behaviour of the ID is never observed in practice because of seismic background noise, the new method is based on a comparison of the seismic noise signal before the arrival and the signal of the arrival itself. The new algorithm allows a fully automatic and unambiguous moment estimate. We apply the algorithm to observations of 30 strong (Mw>6.0) earthquakes around Australia, and compare the result with the moment magnitudes of these earthquakes as published by the USGS. It is found that the new algorithm is more accurate than the standard Mwp method, especially for very large (Mw>7.5) earthquakes.
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nonGeographicDataset
eCat Id
69231
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- External Publication
- ( Theme )
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- seismology
- ( Theme )
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- tsunamis
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2009-06-22T00:00:00
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