Hybrid broadband ground-motion simulation validation of small magnitude active shallow crustal earthquakes in New Zealand

Earthquake Spectra
By: , and 

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Abstract

This article presents a comprehensive validation of the hybrid broadband ground-motion simulation approach (via the commonly used Graves and Pitarka method) in a New Zealand context with small magnitude point source ruptures using an extensive set of 5218 ground motions recorded at 212 sites from 479 active shallow crustal earthquakes across the country. Modifications to the simulation method inferred from a previous New Zealand validation are implemented, and the improvements are explicitly quantified. Empirical ground-motion models are also considered to provide a benchmark for simulation prediction accuracy and precision. Examination of intensity measure residuals identifies that the simulation method modifications lead to reduced model prediction bias and within-event variability and provides evidence toward the use of spatially varying coefficient models for simulation parameters, such as the high-frequency Brune stress parameter. Additional biases identified include, among others, underprediction of significant durations at soft soil sites and overprediction of short-period pseudo-spectral accelerations at stiff alluvial gravel and rock sites due to low-estimated 30 m time-averaged shear-wave velocity values.

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Publication type Article
Publication Subtype Journal Article
Title Hybrid broadband ground-motion simulation validation of small magnitude active shallow crustal earthquakes in New Zealand
Series title Earthquake Spectra
DOI 10.1177/87552930221109297
Volume 38
Issue 4
Year Published 2022
Language English
Publisher SAGE publishing
Contributing office(s) Earthquake Science Center
Description 32 p.
First page 2548
Last page 2579
Country New Zealand
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