ShakeAlert® Version 3: Expected Performance in Large Earthquakes

ABSTRACT The ShakeAlert earthquake early warning (EEW) system partners along with U.S. Geological Survey (USGS) licensed operators deliver EEW alerts to the public and trigger automated systems when a significant earthquake is expected to impact California, Oregon, or Washington. ShakeAlert’s primary goal is to provide usable warning times before the arrival of damaging shaking. EEW is most likely to achieve this goal in large-magnitude earthquakes. In recent years, ShakeAlert has gone through a series of upgrades to its underlying scientific algorithms aimed at improved performance during large earthquakes. Version 3 of this software recently went live in the production system and includes improvements to all algorithms. The main seismic algorithms that detect an earthquake and characterize its location, magnitude, and fault rupture orientation are faster than older versions. Other key changes include: using real-time geodetic data to characterize the magnitude growth in large earthquakes; the introduction of an alert pause procedure to compromise between speed near the epicenter and improved accuracy at larger distances; and the inclusion of a nonergodic site-response model in the ground-motion predictions. ShakeAlert has achieved its primary goal of usable warning times before strong shaking at some locations in real-time operations in recent M 6 earthquakes. Using offline tests, we demonstrate usable warning times are possible for many sites with peak shaking values of modified Mercalli intensity (MMI) 7–8 in M 7+ earthquakes and also for many MMI 8–9 sites in M 8+ earthquakes. ShakeAlert partners use a variety of MMI and magnitude thresholds in deciding when to alert their users within bounds set by the USGS. Our study shows that there is room to raise the magnitude thresholds up to about M 5.5 without adversely affecting performance in large earthquakes. The ground-motion criteria are more complex owing to a significant drop-off in warning times between the MMI 4 and 5 levels of predicted shaking. However, widely used ShakeAlert products, such as the MMI 3 and 4 contour products, can provide sufficiently long warning times before strong shaking in moderate-to-great earthquakes to enable a range of protective actions.

Authors

Institutions

Publication Details

Journal
Bulletin of the Seismological Society of America
Published
2025-02-06
DOI
https://doi.org/10.1785/0120240189
Citations
12
Primary Topic
Seismic Performance and Analysis
Type
article
Field-Weighted Citation Impact
11.44
Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

ShakeAlert® Version 3: Expected Performance in Large Earthquakes

J. K. Saunders, V. M. Santillan, Mario Aranha, Walter Szeliga et al.
12 citations
Bulletin of the Seismological Society of America
Seismic Performance and Analysis
11.44
article

ShakeAlert® Version 3: Expected Performance in Large Earthquakes

J. K. Saunders, V. M. Santillan, Mario Aranha, Walter Szeliga, D. E. Smith, Steve Guiwits, G. P. Biasi, Grace A. Parker, Jennifer R. Andrews, I. H. Henson, T. I. Melbourne, Renate Hartog, Minh Huynh, Thomas H. Heaton, Maren Böse, Allen Husker, Harold Tobin, Carl W. Ulberg, J. J. McGuire, Julian Bunn, Angela Lux, Douglas D. Given, Valerie Thomas, Sumant Jha, J. R. Murray, R. M. Allen, Craig W. Scrivner, A. Baltay, M. H. Murray, C. Felizardo, V. C. Kress, Brendan W. Crowell, Robert M. de Groot, Sara K. McBride, Anthony Good
article en
12 citations

Abstract

ABSTRACT The ShakeAlert earthquake early warning (EEW) system partners along with U.S. Geological Survey (USGS) licensed operators deliver EEW alerts to the public and trigger automated systems when a significant earthquake is expected to impact California, Oregon, or Washington. ShakeAlert’s primary goal is to provide usable warning times before the arrival of damaging shaking. EEW is most likely to achieve this goal in large-magnitude earthquakes. In recent years, ShakeAlert has gone through a series of upgrades to its underlying scientific algorithms aimed at improved performance during large earthquakes. Version 3 of this software recently went live in the production system and includes improvements to all algorithms. The main seismic algorithms that detect an earthquake and characterize its location, magnitude, and fault rupture orientation are faster than older versions. Other key changes include: using real-time geodetic data to characterize the magnitude growth in large earthquakes; the introduction of an alert pause procedure to compromise between speed near the epicenter and improved accuracy at larger distances; and the inclusion of a nonergodic site-response model in the ground-motion predictions. ShakeAlert has achieved its primary goal of usable warning times before strong shaking at some locations in real-time operations in recent M 6 earthquakes. Using offline tests, we demonstrate usable warning times are possible for many sites with peak shaking values of modified Mercalli intensity (MMI) 7–8 in M 7+ earthquakes and also for many MMI 8–9 sites in M 8+ earthquakes. ShakeAlert partners use a variety of MMI and magnitude thresholds in deciding when to alert their users within bounds set by the USGS. Our study shows that there is room to raise the magnitude thresholds up to about M 5.5 without adversely affecting performance in large earthquakes. The ground-motion criteria are more complex owing to a significant drop-off in warning times between the MMI 4 and 5 levels of predicted shaking. However, widely used ShakeAlert products, such as the MMI 3 and 4 contour products, can provide sufficiently long warning times before strong shaking in moderate-to-great earthquakes to enable a range of protective actions.

Bulletin of the Seismological Society of AmericaVol. 115(2)
GNS Science (NZ), California Institute of Technology (US), United States Geological Survey (US), Universities Space Research Association (US), Central Washington University (US), ETH Zurich (CH), Earth and Space Research (US), University of California, Berkeley (US)
Openalex Percentile: Top 1%
Seismic Performance and Analysis
11.44
DOISourceOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.