Title: Peak Ground Displacement Saturates Exactly When Expected: Implications for Earthquake Early Warning

Abstract

The scaling of rupture properties with magnitude is of critical importance to earthquake early warning (EEW) systems that rely on source characterization using limited snapshots of waveform data. ShakeAlert, a prototype EEW system that is being developed for the western United States, provides real-time estimates of earthquake magnitude based on P-wave peak ground displacements calculated at stations triggered by the event. The algorithms used in ShakeAlert assume that the displacement measurements at each station are statistically independent and that there exists a linear and time-independent relation between log peak ground displacement and earthquake magnitude. Here we challenge this basic assumption using the largest dataset assembled for this purpose to date: a comprehensive database of more than 140,000 vertical-component waveforms from M4.5–M9 earthquakes occurring near Japan from 1997 through 2018 and recorded by the K-NET and KiK-net strong-motion networks. By analyzing the time-evolution of P-wave peak ground displacements for these earthquakes, we show that there is a break, or saturation, in the magnitude-displacement scaling that depends on the length of the measurement time window. We demonstrate that the magnitude at which this saturation occurs is well-explained by a simple and non-deterministic model of earthquake rupture growth. We then utilize the predictionsmore » of this saturation model to develop a Bayesian framework for estimating posterior uncertainties in real-time magnitude estimates.« less

Authors:

Trugman, Daniel T.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9296-4223"
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Page, Morgan T.  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-9321-2990"
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Minson, Sarah E.  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-5869-3477"
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Cochran, Elizabeth S.  ^[2]

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• Search DOE PAGES for ORCID "0000-0003-2485-4484"
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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. US Geological Survey, Pasadena, CA (United States)
3. US Geological Survey, Menlo Park, CA (United States)

Publication Date:

2019-04-16

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1508560

Alternate Identifier(s):

OSTI ID: 1510164

Report Number(s):

LA-UR-18-30809
Journal ID: ISSN 2169-9313

Grant/Contract Number:  

89233218CNA000001; 20180700PRD1

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Solid Earth

Additional Journal Information:

Journal Volume: 124; Journal Issue: 5; Journal ID: ISSN 2169-9313

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Earthquake Early Warning; Rupture Determinism; Earthquake scaling; Bayesian estimation