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Conditional spectrum computation incorporating multiple causal earthquakes and ground-motion prediction models

Bulletin of the Seismological Society of America

By:
, , , and
DOI: 10.1785/0120110293

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Abstract

The conditional spectrum (CS) is a target spectrum (with conditional mean and conditional standard deviation) that links seismic hazard information with ground-motion selection for nonlinear dynamic analysis. Probabilistic seismic hazard analysis (PSHA) estimates the ground-motion hazard by incorporating the aleatory uncertainties in all earthquake scenarios and resulting ground motions, as well as the epistemic uncertainties in ground-motion prediction models (GMPMs) and seismic source models. Typical CS calculations to date are produced for a single earthquake scenario using a single GMPM, but more precise use requires consideration of at least multiple causal earthquakes and multiple GMPMs that are often considered in a PSHA computation. This paper presents the mathematics underlying these more precise CS calculations. Despite requiring more effort to compute than approximate calculations using a single causal earthquake and GMPM, the proposed approach produces an exact output that has a theoretical basis. To demonstrate the results of this approach and compare the exact and approximate calculations, several example calculations are performed for real sites in the western United States. The results also provide some insights regarding the circumstances under which approximate results are likely to closely match more exact results. To facilitate these more precise calculations for real applications, the exact CS calculations can now be performed for real sites in the United States using new deaggregation features in the U.S. Geological Survey hazard mapping tools. Details regarding this implementation are discussed in this paper.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Conditional spectrum computation incorporating multiple causal earthquakes and ground-motion prediction models
Series title:
Bulletin of the Seismological Society of America
DOI:
10.1785/0120110293
Volume
103
Issue:
2A
Year Published:
2013
Language:
English
Publisher:
Seismological Society of America
Publisher location:
Stanford, CA
Description:
14 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Bulletin of the Seismological Society of America
First page:
1103
Last page:
1116