A series of earthquakes struck the Bay Area city of San Ramon on February 2nd, beginning with a magnitude 3.8 quake approximately 2.4 miles southeast of the city, according to the U.S. Geological Survey.
Earthquake Sequence in San Ramon
The initial quake, reported at a depth of about 6 miles, was followed by three more earthquakes within the next half hour, registering magnitudes of 3.3, 2.5, and 2.5. The largest quake in the sequence reached a magnitude of 4.2 at around 7:01 a.m., also at a depth of nearly 6 miles. The USGS recorded approximately 15 additional quakes before 8:45 a.m., ranging in magnitude from 2.5 to 3.8.
California Earthquake History
The San Francisco Bay Area has a long history of seismic activity. The largest recorded earthquake in California history was the Great 1906 San Francisco Earthquake, which registered a magnitude of 7.7, according to the U.S. Geological Survey. The quake occurred at approximately 5:12 a.m. on April 18th.
According to the California Department of Conservation, the largest earthquakes in California since 1800 include a magnitude 7.9 quake in Fort Tejon (1857), the 7.8 magnitude 1906 San Francisco earthquake, and a 7.4 magnitude quake in Owens Valley (1872).
What to Do During an Earthquake
Experts recommend the “drop, cover, and hold on” method during an earthquake to protect against falling debris and being crushed. This involves dropping to the ground, covering the head and neck, and seeking shelter under a sturdy table or desk if available.
If driving during an earthquake, the California Highway Patrol advises slowing down and pulling over to a safe location. Remain in the vehicle with your seatbelt fastened, engine off, and parking brake set until the shaking stops. Afterward, check for damage and injuries before resuming travel cautiously, avoiding damaged roads, bridges, and ramps.
Understanding Earthquake Science
The Earth is composed of four layers: the inner core, outer core, mantle, and crust. The crust and the upper part of the mantle form the lithosphere, which is fragmented into moving tectonic plates. As these plates interact – bumping and colliding – stress builds up along their edges, creating faults. When the friction along these faults exceeds the strength of the rocks, energy is released in the form of seismic waves, causing an earthquake.
Future Seismic Activity
Currently, it is not possible to predict earthquakes. However, the USGS can calculate the probability of a significant earthquake occurring in a specific area within a given timeframe. These forecasts are similar to climate and weather predictions, not precise predictions of when an earthquake will happen. A USGS map indicates that much of California has a greater than 95% chance of experiencing a damaging earthquake in the next 100 years.
Addressing Common Misconceptions
Contrary to popular belief, California will not “fall into the ocean” due to earthquakes. The Seismology Laboratory at Berkeley clarified that earthquakes in California cause horizontal motion, not the creation of sinkholes or landmasses breaking off into the sea. While the coastline will continue to shift over millions of years, the state is not at risk of suddenly sinking into the Pacific.
Frequently Asked Questions
What was the magnitude of the largest earthquake in the San Ramon sequence?
The highest magnitude quake in the sequence hit the area at around 7:01 a.m., registering at 4.2, according to the U.S. Geological Survey.
What is the largest earthquake ever recorded in California?
The largest recorded earthquake in California history was the Great 1906 San Francisco Earthquake, which registered a magnitude of 7.7, according to the U.S. Geological Survey.
Is it possible to predict when the next earthquake will occur in California?
It is not currently possible to predict an earthquake, though USGS scientists can calculate the probability that a significant earthquake will occur in a specific area within a certain number of years, according to the USGS.
What are your thoughts on earthquake preparedness in California, and what steps do you think individuals and communities should take to mitigate risk?
Worth a look