CONTRA COSTA COUNTY, CA — the U.S. Geological Survey reported that a 2.7 magnitude quake rattled close to San Ramon Saturday evening.

The tremor, which struck the area at 8:21 p.m., was centered roughly 2 miles east-southeast of San Ramon. It occurred at a depth of 4 miles. Seismologists first reported it as a 2.8 event, but later downgraded it to 2.7.

Did you feel it?

Those who experienced the earthquake are encouraged to report it via the USGS Felt Report form. So far, the agency has collected 68 online responses from individuals indicating that they felt the quake. Weak to light shaking has been recorded and residents reported experiencing the tremor in a couple of cities, including Danville and San Ramon, according to the USGS DYFI report.

Did you capture the effect?

We welcome your images illustrating how the quake affected your area. Share them with us at sacbee.com/customer-service/submit-photo.

Earthquakes last week

Over the last week, five quakes of magnitude 2.5 or greater have been detected in the region. The strongest, a 3.0 magnitude quake, was registered in the same region prior to this quake.

The five largest nearby quakes from last week:

• 3.0, east-southeast of San Ramon on Jan. 10
• 2.9, east-southeast of San Ramon on Jan. 9
• 2.8, east-southeast of San Ramon on Jan. 9
• 2.6, east-southeast of San Ramon on Jan. 9
• 2.5, west-northwest of Bayview-Montalvin on Jan. 5

What to know about earthquakes

Magnitude measures the energy released at the source of the earthquake, the U. S. Geological Survey says. It replaces the old Richter scale. Quakes between 2.5 and 5.4 magnitude are often felt but rarely cause much damage, according to Michigan Tech. Earthquakes below 2.5 magnitude are seldom felt by most people.

Earthquakes’ sudden, rapid shaking can cause fires, tsunamis, landslides or avalanches. They can happen anywhere, but are most common in Alaska, California, Hawaii, Oregon, Puerto Rico and Washington, according to the Department of Homeland Security.

It is estimated that there are 500,000 detectable earthquakes in the world each year. 100,000 of those can be felt, and 100 of them cause damage.

What to do during an earthquake

If an earthquake strikes, it’s best to protect yourself right away. Here are tips from experts:

If you’re in a car: Pull over and stop. Set your parking brake.

If you’re in bed: Turn face-down and cover your head with a pillow.

If you’re outdoors: Stay away from buildings. Don’t go inside.

If you’re inside: Stay and don’t run outdoors. Stay away from doorways.

The best way to protect yourself during an earthquake is to drop, cover and hold on, officials say. “Wherever you are, drop down to your hands and knees and hold onto something sturdy,” officials say. “If you’re using a wheelchair or walker with a seat, make sure your wheels are locked and remain seated until the shaking stops.” Be sure to cover your head and neck with your arms, and crawl under a sturdy table if possible. If no shelter is available, crawl to an interior wall away from windows. Once under a table, officials say you should hold on with one hand and be ready to move with it.

“There can be serious hazards after an earthquake, such as damage to the building, leaking gas and water lines, or downed power lines,” officials say. “Expect aftershocks to follow the main shock of an earthquake. Be ready to Drop, Cover, and Hold On if you feel an aftershock.”

Source: The U.S. Geological Survey