End-users in California, Oregon, and Washington receive ShakeAlert-powered alerts only if certain thresholds for magnitude and shaking intensity are met, as identified below. The ShakeAlert system only issues a ShakeAlert Message if the earthquake is expected to produce weak or greater shaking that can potentially produce strong shaking. It is important to note that not all Technical Partner delivery methods have the same alerting thresholds and may not all activate for a given earthquake.
To learn more about earthquake magnitude and intensity and how these thresholds were selected, read the Magnitude, Intensity and ShakeAlert FAQ.