A Caltech Library Service

Earthquake Early Warning ShakeAlert 2.0: Public Rollout

Kohler, Monica D. and Smith, Deborah E. and Andrews, Jennifer and Chung, Angela I. and Hartog, Renate and Henson, Ivan and Given, Douglas D. and de Groot, Robert and Guiwits, Stephen (2020) Earthquake Early Warning ShakeAlert 2.0: Public Rollout. Seismological Research Letters, 91 (3). pp. 1763-1775. ISSN 0895-0695. doi:10.1785/0220190245.

[img] PDF - Accepted Version
See Usage Policy.

[img] PDF (Supplementary data) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


The ShakeAlert earthquake early warning system is designed to automatically identify and characterize the initiation and rupture evolution of large earthquakes, estimate the intensity of ground shaking that will result, and deliver alerts to people and systems that may experience shaking, prior to the occurrence of shaking at their location. It is configured to issue alerts to locations within the West Coast of the United States. In 2018, ShakeAlert 2.0 went live in a regional public test in the first phase of a general public rollout. The ShakeAlert system is now providing alerts to more than 60 institutional partners in the three states of the western United States where most of the nation’s earthquake risk is concentrated: California, Oregon, and Washington. The ShakeAlert 2.0 product for public alerting is a message containing a polygon enclosing a region predicted to experience modified Mercalli intensity (MMI) threshold levels that depend on the delivery method. Wireless Emergency Alerts are delivered for M 5+ earthquakes with expected shaking of MMI≥IV⁠. For cell phone apps, the thresholds are M 4.5+ and MMI≥III⁠. A polygon format alert is the easiest description for selective rebroadcasting mechanisms (e.g., cell towers) and is a requirement for some mass notification systems such as the Federal Emergency Management Agency’s Integrated Public Alert and Warning System. ShakeAlert 2.0 was tested using historic waveform data consisting of 60 M 3.5+ and 25 M 5.0+ earthquakes, in addition to other anomalous waveforms such as calibration signals. For the historic event test, the average M 5+ false alert and missed event rates for ShakeAlert 2.0 are 8% and 16%. The M 3.5+ false alert and missed event rates are 10% and 36.7%. Real‐time performance metrics are also presented to assess how the system behaves in regions that are well‐instrumented, sparsely instrumented, and for offshore earthquakes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Andrews, Jennifer0000-0002-5679-5565
Additional Information:© 2020 Seismological Society of America. Manuscript received 4 September 2019; Published online 8 April. Funding for ShakeAlert has been provided primarily by the U.S. Geological Survey (USGS), California Governor's Office of Emergency Services (Cal OES), the State of Oregon, and the Gordon and Betty Moore Foundation. The authors are grateful for the useful and comprehensive reviews of this article provided by Sarah Minson and Debi Kilb. Credit goes to Elijah Marchese for creating Figure S4. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Data and Resources: All historic event test data used here can be found at Some plots were made using the Generic Mapping Tools v.4.2.1 (; Wessel and Smith, 1998). Open‐source Neural Autonomic Transport System (NATS) messaging system software can be downloaded from The ShakeMap scenario data are available from The Hayward scenario data can be found at The San Andreas scenario data are from The Cascadia scenario data are from The other relevant data are from and All websites were last accessed in March 2020. Supplemental material contains four figures and a detailed description of ground‐motion assessment tests.
Group:Seismological Laboratory
Funding AgencyGrant Number
California Office of Emergency ServicesUNSPECIFIED
State of OregonUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20200506-122500671
Persistent URL:
Official Citation:Monica D. Kohler, Deborah E. Smith, Jennifer Andrews, Angela I. Chung, Renate Hartog, Ivan Henson, Douglas D. Given, Robert de Groot, Stephen Guiwits; Earthquake Early Warning ShakeAlert 2.0: Public Rollout. Seismological Research Letters ; 91 (3): 1763–1775. doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103034
Deposited By: Tony Diaz
Deposited On:06 May 2020 19:36
Last Modified:16 Nov 2021 18:17

Repository Staff Only: item control page