Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
This is b-roll footage of a ShakeAlert earthquake early warning system seismic station. These seismic stations and sensors are deployed around California and are used to monitor earthquake activity.
Public Domain.