Earthquake Education Center
Understanding earthquakes is the first step to being prepared. Learn the science, know the risks, and be ready for the Bay Area's seismic reality.
For Kids: What is an Earthquake?
The Earth isn't one solid piece — it's more like a cracked eggshell! The outer layer is made up of giant pieces called tectonic plates that fit together like a puzzle. These plates are always moving, very slowly.
When two plates push against each other, they can get stuck. Pressure builds up, like when you push two magnets together. Eventually, the plates slip past each other suddenly — and that's an earthquake!
Fun Facts
- Earth has about 500,000 detectable earthquakes every year. Only 100,000 can be felt.
- Some animals can sense earthquakes before humans feel them.
- The largest earthquake ever recorded was a 9.5 in Chile in 1960.
- Earthquakes happen under the ocean too — they can cause tsunamis!
The 3 Steps: Drop, Cover, Hold On
Source: ShakeOut.orgDROP
Get down on your hands and knees. This protects you from falling and lets you crawl to shelter.
COVER
Get under a sturdy desk or table. Cover your head and neck with your arms if no shelter is nearby.
HOLD ON
Stay under cover and hold on until the shaking stops. Be prepared to move with your shelter.
Download official graphics for your home, school, or workplace:
Understanding Magnitude
The Richter magnitude scale is logarithmic — each whole number increase represents 10× more ground motion and about 31× more energy released. A magnitude 5.0 earthquake releases 31 times more energy than a 4.0, and nearly 1,000 times more than a 3.0.
Rarely felt by people. Recorded only by seismometers. About 1,300 happen daily worldwide.
Often felt, but rarely causes damage. Similar to a large truck passing nearby.
Noticeable shaking indoors. Windows rattle, objects on shelves may fall.
Can cause damage to weak buildings. Felt widely over large areas.
Destructive in areas up to 100 miles. Can topple poorly constructed buildings.
Causes serious damage over large areas. The 1989 Loma Prieta earthquake was 6.9.
Can cause serious damage in areas several hundred miles across.
Bay Area Fault Lines
The San Francisco Bay Area sits on one of the most seismically active regions in the United States. Several major fault systems run through our region, each capable of producing significant earthquakes.
San Andreas Fault
The most famous fault in California. Runs 800 miles from the Salton Sea to Cape Mendocino. The 1906 San Francisco earthquake (M7.9) caused over 3,000 deaths.
Hayward Fault
Runs through the East Bay, directly beneath UC Berkeley, Oakland, and Fremont. Scientists consider it the most dangerous fault in the Bay Area due to urban density.
Calaveras Fault
Eastern fault zone running through San Ramon, Dublin, Fremont, and into Silicon Valley. Known for frequent earthquake swarms.
Rodgers Creek Fault
Northern extension of the Hayward Fault, through Sonoma and Napa wine country. Ruptured during the 2014 South Napa earthquake.
Explore the Full Interactive Map
View detailed fault traces, slip rates, and earthquake history from USGS.
What is an Earthquake Swarm?
An earthquake swarm is a series of many small earthquakes occurring in a localized area over days to weeks, without a clear mainshock-aftershock pattern. Unlike typical earthquake sequences where one large quake triggers smaller aftershocks, swarms involve numerous similar-sized events.
The San Ramon/Dublin area frequently experiences earthquake swarms along the Calaveras Fault. These swarms are caused by fluids moving through fault zones, reducing friction and allowing small slips to occur.
Are swarms dangerous?
Most swarms consist of small earthquakes (M2-3) and pose no direct danger. Scientists monitor them because in rare cases, they can precede larger earthquakes. However, the vast majority of Bay Area swarms end without producing damaging events.
How scientists detect swarms
- 1.Multiple small earthquakes within a tight geographic area
- 2.No clear "mainshock" — events are similar in size
- 3.Activity elevated above normal background rate
- 4.Usually concentrated within 72 hours
Emergency Preparedness
The Bay Area will experience a major earthquake. The question isn't if, but when. Being prepared can save your life and make recovery much easier.
Essential Emergency Kit
Get prepared with quality emergency supplies from our trusted partners.
During an Earthquake
If you're indoors:
- • Drop, Cover, and Hold On
- • Stay away from windows and heavy objects
- • Stay inside until shaking stops
- • DO NOT run outside or to doorways
If you're outdoors:
- • Move to a clear area away from buildings
- • Avoid power lines and trees
- • Drop to the ground if you can't move
If you're driving:
- • Pull over safely to the side
- • Avoid bridges, overpasses, and power lines
- • Stay in your car until shaking stops
ShakeAlert: Early Warning System
ShakeAlert is the earthquake early warning system for the West Coast. It can give you seconds to tens of seconds of warning before shaking reaches your location.
While it can't predict earthquakes, it detects them as they begin and sends alerts faster than seismic waves travel. Those few seconds can be crucial for taking cover or stopping machinery.
How much warning will I get?
Warning time depends on your distance from the earthquake epicenter and how quickly the system can process and deliver the alert.
Official Resources
Official earthquake monitoring and data
Research and monitoring for Northern California
Federal emergency preparedness guide
Early warning system for the West Coast
State geological hazard information
San Francisco emergency preparedness