SAN FRANCISCO—The San Francisco Bay Area was hit with a 3.6 earthquake on Thursday, December 31 at 5:41 a.m. The earthquake reportedly struck around the San Andreas Fault, which is nine miles away from San Francisco.
San Franciscans described their experience on Twitter. “It woke me up. It sounded like a big explosion and the house jolted,” said one Twitter user. Others said they felt the earthquake in Larkspur, San Rafael, San Anselmo, and Novato.
A website called VolcanoDiscovery.com has a monitoring service that benefits the BBC, CNN, Discovery Channel, and National Geographic television channels. According to their reports, “Many users described the sensation as garbage trucks passing in front of their homes, often accompanied by a strong bump or a boom. Some thought it was an explosion, while others reported a single big jolt… Hundreds of beds shook and swayed this morning with many alarmed that something or somebody was jumping on their mattress.”
The United States Geological Survey (USGS) explained the “booms” are “actually some type of cultural noise, such as some type of explosion, a large vehicle going by, or sometimes a sonic boom, but there have been many reports of ‘booms’ that cannot be explained by man-made sources. No one knows for sure, but scientists speculate that these ‘booms’ are probably small shallow earthquakes that are too small to be recorded, but large enough to be felt by people nearby.”
The boom sounds tend to occur in the Northeastern U.S. and along the East Coast, the USGS indicated.
VolcanoDiscovery noted the earthquake that hit the San Francisco region on December 31 was not considered to be strong, because “the quake was located at a shallow depth of 8.9 miles. Shallow earthquakes are felt more strongly than deeper ones as they are closer to the surface.”
The San Francisco Bay Area has experienced four earthquakes with a magnitude of 3.0 or above and 17 earthquakes between 2.0-3.0 magnitude within the last 30 days, VolcanoDiscovery indicated.
“There were also 72 quakes below magnitude 2.0 which people don’t normally feel,” the Volcano Discovery website stated.
The San Francisco region experienced another earthquake, about three hours later at 8:17 a.m. on December 31, the USGS reported. This earthquake, according to the experts at VolcanoDiscovery, was a 0.8 earthquake about 1.5 miles northwest of Orinda, Contra Costa County.
The USGS published these tips on their website for people to know in case an earthquake occurs:
- If you are indoors — stay there! Get under a desk or table and hang on to it or move into a hallway or against an inside wall. Stay clear of windows, fireplaces, and heavy furniture or appliances. Get out of the kitchen, which is a dangerous place (things can fall on you). Don’t run downstairs or rush outside while the building is shaking or while there is a danger of falling and hurting yourself or being hit by falling glass or debris.
- If you are outside — get into the open, away from buildings, power lines, chimneys, and anything else that might fall on you.
- If you are driving — stop, but carefully. Move your car as far out of traffic as possible. Do not stop on or under a bridge or overpass or trees, light posts, power lines, or signs. Stay inside your car until the shaking stops. When you resume driving, watch for breaks in the pavement, fallen rocks, and bumps in the road at bridge approaches.