Quick Quake Briefing: ShakeAlert and the 2025 Earthquake Swarms in Southern California

The EERI Northern California Regional Chapter hosted a free webinar on the recent earthquake swarms in Southern California. Over the past year, Southern California has been experiencing a notable increase in seismic activity, with a surge in moderate earthquakes not seen in decades. Fortunately, the earthquake intensities are such that little to no damage has occurred to the built environment. During some of these earthquakes, many residents received warning notifications on their cell phones from the ShakeAlert earthquake early warning system. Susan E. Hough, PhD, Seismologist with the U.S. Geological Survey Seismic Hazards Program, presented on the seismology of the earthquake swarms, and Robert de Groot, PhD, Physical Scientist with the USGS, presented on ShakeAlert performance.