What “Did You Feel It?” Data Can Tell Us About Earthquake Early Warning Performance
Description:
We examine responses to the U.S. Geological Survey’s “Did You Feel It?” (DYFI) survey and Earthquake Early Warning (EEW) companion questionnaire to assess the performance of the ShakeAlert EEW system for the West Coast of the United States. ShakeAlert rapidly detects and characterizes earthquakes and develops the EEW alert information, but it is up to official alert delivery partners to issue these alerts to people and other system users. As such, it is often unknown how many people were alerted and when. We examine the DYFI reports for several recent earthquakes with ShakeAlert-powered alerts that resulted in substantial responses to the DYFI EEW questionnaire, including the 2024 M7.0 offshore Cape Mendocino earthquake. We find that instances of magnitude overestimation by ShakeAlert relative to catalog source values do not necessarily indicate that there was significant over-alerting relative to the observed ground motions, and that comparisons to reported intensities from DYFI provide a better assessment of ShakeAlert’s ground-motion prediction accuracy. Perceived warning times from the DYFI EEW questionnaire show that estimating maximum-expected warning times using the S-wave arrival is a reasonable assumption when discussing public EEW performance, except in higher-intensity areas where P-waves should be widely perceived. We also find many reports of shorter warning times, late alerts, and missed alerts in locations where longer warning times are expected based on the alert publication times from the ShakeAlert system; this suggests that alert delivery latencies may be substantial and highly variable. Overall, we find that the DYFI survey provides useful EEW efficacy information and can be used to inform our choices for how to convey the performance of the ShakeAlert system.
Session: Adventures in Social Seismology: Ethical Engagement, Earthquake Early Warnings, Operational Forecasts, and Beyond [Poster]
Type: Poster
Date: 4/15/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Jessie
Student Presenter: No
Invited Presentation:
Poster Number: 128
Authors
Jessie Saunders Presenting Author Corresponding Author jsaunder@caltech.edu California Institute of Technology |
David Wald wald@usgs.gov U.S. Geological Survey |
Sara M McBride skmcbride@usgs.gov U.S. Geological Survey |
Vincent Quitoriano vinceq@contractor.usgs.gov U.S. Geological Survey |
|
|
|
|
|
What “Did You Feel It?” Data Can Tell Us About Earthquake Early Warning Performance
Category
Adventures in Social Seismology: Ethical Engagement, Earthquake Early Warnings, Operational Forecasts, and Beyond