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Estimation of the high-frequency radiation of the 2000 Tottori (Japan) earthquake based on a dynamic model of fault rupture; application to the strong ground motion simulation

Nelson Pulido and Luis A. Dalguer
Estimation of the high-frequency radiation of the 2000 Tottori (Japan) earthquake based on a dynamic model of fault rupture; application to the strong ground motion simulation
Bulletin of the Seismological Society of America (August 2009) 99 (4): 2305-2322

Abstract

In the present study we investigate the high-frequency (HF) radiation mechanism of the 2000 Tottori earthquake in Japan based on a 3D spontaneous fault rupture dynamic model. We generalize the model of HF radiation of a suddenly stopping circular crack (Madariaga, 1977; Boatwright, 1982) to the radiation from a general 3D rupture in a planar fault, where HF is radiated during gradual changes of rupture velocity at the rupture front. Local rupture velocity changes are expressed as the divergence of local rupture velocity vectors that are derived from gradients of rupture times from the dynamic model. Our numerical model of the Tottori earthquake indicates that rupture velocity changes are largely induced by barriers (locally stronger fault sections) across the fault plane and that HF radiation mainly originates within asperities (large stress-drop regions) in areas where the product of dynamic stress drop and rupture velocity changes is maximum. We develop a strong ground motion simulation methodology that incorporates HF radiation inferred from a dynamic fault rupture model. Using this methodology we investigate the HF radiation of the Tottori earthquake by inverting observed near-source acceleration envelopes of the earthquake. Our inversion results corroborate that HF radiation originates within asperities and show that significant HF radiation represents no more than a 20% of the total asperity area. Our results show that the incorporation of a directivity factor, on the basis of a well-defined physical rupture model to the radiation pattern leads to a significant improvement in fitting of observed ground motions. Our simulated near-source strong ground motions of the Tottori earthquake are also able to reproduce the omega (super -2) radiation theoretically predicted in 2D dynamic fault rupture models.


ISSN: 0037-1106
EISSN: 1943-3573
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 99
Serial Issue: 4
Title: Estimation of the high-frequency radiation of the 2000 Tottori (Japan) earthquake based on a dynamic model of fault rupture; application to the strong ground motion simulation
Affiliation: National Research Institute for Earth Science and Disaster Prevention, Ibaraki, Japan
Pages: 2305-2322
Published: 200908
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 94
Accession Number: 2009-088546
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, geol. sketch maps
N35°10'00" - N35°19'60", E133°10'00" - E133°30'00"
Secondary Affiliation: Institute of Geophysics, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200948
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