Ground-motion attenuation relationship for the Sumatran megathrust earthquakes

In order to extend the multisource model to vertical ground motion, we fit the vertical ground motion attenuation relationship of the Wenchuan earthquake. Different from traditional attenuation relationship forms, we propose a simplified ground motion attenuation function including site effect via a flag related to VS30. The regression results show that it has site effect on the vertical ground motion of the Wenchuan earthquake and gradually weakens with the increase in periods. According to residuals analysis, the hanging-wall effect on vertical ground motion is strong for the Wenchuan earthquake, especially in short periods. The result analysis indicates that the shape of the vertical response spectrum based on regression is different from that of the horizontal component and complies with the recommended design vertical response spectrum of FEMA P-1050. V/H (vertical-to-horizontal ratios), as a main way to estimate vertical ground motion, cannot be simply fixed as 2/3. Therefore, site location, site condition, and frequency spectrum have to be considered comprehensively. The regression accuracy of the vertical ground motion of the multisource model is slightly higher than that of the point-source model and lower than that of the finite fault source model. It is expected that this model will serve as an alternative for source-to-site distance when multiple asperities are to be modeled in the absence of the detail fault model to get a general scenario of the future ground motions.

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Proposed methodology for estimating the magnitude at which subduction megathrust ground motions and source dimensions exhibit a break in magnitude scaling: Example for 79 global subduction zones

Earthquake Spectra ◽

10.1177/8755293019899957 ◽

2020 ◽

Vol 36 (3) ◽

pp. 1271-1297

Author(s):

Kenneth W. Campbell

Keyword(s):

Ground Motion ◽

Subduction Zones ◽

Ground Motions ◽

Seismic Source ◽

Scaling Relations ◽

Megathrust Earthquakes ◽

Source Dimensions ◽

Magnitude Scaling ◽

Aspect Ratios ◽

Source Scaling

In this article, I propose a method for estimating the magnitude [Formula: see text] at which subduction megathrust earthquakes are expected to exhibit a break in magnitude scaling of both seismic source dimensions and earthquake ground motions. The methodology is demonstrated by applying it to 79 global subduction zones defined in the literature, including Cascadia. Breakpoint magnitude is estimated from seismogenic interface widths, empirical source scaling relations, and aspect ratios of physically unbounded earthquake ruptures and their uncertainties. The concept stems from the well-established observation that source-dimension and ground motion scaling decreases for shallow continental (primarily strike-slip) earthquakes when rupture exceeds the seismogenic width of the fault. Although a scaling break for megathrust earthquakes is difficult to observe empirically, all of the instrumentally recorded historical [Formula: see text] mega-earthquakes have occurred on subduction zones with [Formula: see text] (8.1–8.9), consistent with an observed break in source scaling relations derived from these same events. The breakpoint magnitudes derived in this study can be used to constrain the magnitude at which the scaling of ground motion is expected to decrease in subduction ground motion prediction equations.

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Ground-Motion Attenuation from the 1995 Kobe Earthquake Based on Simulations Using the Hybrid Green's Function Method

Bulletin of the Seismological Society of America ◽

10.1785/0120010163 ◽

2002 ◽

Vol 92 (3) ◽

pp. 1025-1031 ◽

Cited By ~ 9

Author(s):

A. Pitarka

Keyword(s):

Green’S Function ◽

Ground Motion ◽

Green's Function ◽

Function Method ◽

Green’S Function Method ◽

Kobe Earthquake ◽

Ground Motion Attenuation

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A Monte Carlo approach to seismic hazard analysis

Bulletin of the Seismological Society of America ◽

10.1785/bssa0890040854 ◽

1999 ◽

Vol 89 (4) ◽

pp. 854-866 ◽

Cited By ~ 4

Author(s):

John E. Ebel ◽

Alan L. Kafka

Keyword(s):

Monte Carlo ◽

Seismic Hazard ◽

Ground Motion ◽

Epicentral Distance ◽

Ground Motions ◽

Source Parameters ◽

Parametric Models ◽

Earthquake Catalog ◽

Attenuation Relations ◽

Ground Motion Attenuation

Abstract We have developed a Monte Carlo methodology for the estimation of seismic hazard at a site or across an area. This method uses a multitudinous resampling of an earthquake catalog, perhaps supplemented by parametric models, to construct synthetic earthquake catalogs and then to find earthquake ground motions from which the hazard values are found. Large earthquakes extrapolated from a Gutenberg-Richter recurrence relation and characteristic earthquakes can be included in the analysis. For the ground motion attenuation with distance, the method can use either a set of observed ground motion observations from which estimates are randomly selected, a table of ground motion values as a function of epicentral distance and magnitude, or a parametric ground motion attenuation relation. The method has been tested for sites in New England using an earthquake catalog for the northeastern United States and southeastern Canada, and it yields reasonable ground motions at standard seismic hazard values. This is true both when published ground motion attenuation relations and when a dataset of observed peak acceleration observations are used to compute the ground motion attenuation with distance. The hazard values depend to some extent on the duration of the synthetic catalog and the specific ground motion attenuation used, and the uncertainty in the ground motions increases with decreasing hazard probability. The program gives peak accelerations that are comparable to those of the 1996 U.S. national seismic hazard maps. The method can be adapted to compute seismic hazard for cases where there are temporal or spatial variations in earthquake occurrence rates or source parameters.

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