KQED's Forum How Freaked Out Should We Be About All These Small Earthquakes?
Dec 15, 2025
In this enlightening discussion, Richard Allen, director of the Berkeley Seismological Laboratory, and Annemarie Baltay, a research geophysicist from the USGS, tackle the recent surge of small earthquakes in the Bay Area. They clarify that these swarms don't signify an impending big quake and explain how earthquake swarms differ from mainshock-aftershock sequences. They delve into the complex fault systems like Calaveras and San Andreas, the unpredictability of quakes, and the advancements in early warning systems, urging residents to stay prepared.
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Swarms Often Come And Go
- Earthquake swarms are common and typically flare up for days to weeks before fading away.
- Richard Allen says San Ramon’s swarm is not unusual based on past decades of similar events.
Probabilities Over Decades, Not Timetables
- The USGS gives long-term probabilities rather than exact predictions, e.g., a ~72% chance of M6.7+ in the Bay Area by 2043.
- Annemarie Baltay explains these outlooks show where risk concentrates but not precise timing.
Faults Radiate Useful Signals
- Hayward and Calaveras faults emit measurable signals like creep and repeating quakes that give scientists useful data.
- Richard Allen says these signals could help improve understanding of where we are in the earthquake cycle.