4.4 magnitude earthquake in Sonoma County
On April 11, 2023, a moderate 4.4 magnitude earthquake struck 28 miles north of Santa Rosa, Sonoma County, California, at 10:39 pm local time. The quake was recorded at a shallow depth of 1.2 miles below the surface. Although many people in the area likely felt the shaking, it was not expected to cause significant damage beyond objects falling from shelves or broken windows.
ShakeAlert Earthquake Early Warning System
Many Sonoma County residents were alerted by the ShakeAlert Earthquake Early Warning System just before the earthquake was felt. ShakeAlert is not an earthquake prediction tool; rather, it detects significant earthquakes quickly enough to send alerts to people before the shaking arrives. This system can provide valuable seconds to tens of seconds of warning time, allowing residents to take protective actions such as moving away from dangerous machines, seeking cover under a desk, or slowing down vehicles.
Impact on nearby communities
The earthquake was felt in several nearby communities, with light shaking experienced in Cobb, which is located 5 miles from the epicenter. Weak shaking may have been felt in Cloverdale, Clearlake, Russian River, Windsor, Santa Rosa, Ukiah, and Rohnert Park. Very weak shaking might have been experienced in Petaluma, which is located 43 miles from the epicenter.
Seismic activity in California
This recent earthquake serves as a reminder that California, and the Bay Area in particular, is located in a seismically active region. The area is home to several major fault lines, including the San Andreas Fault, which is capable of producing large earthquakes of magnitude 7.0 or greater. Other major fault lines in the region include the Hayward Fault and the Calaveras Fault, both of which are also capable of producing large earthquakes.
Given the earthquake risks in the region, it is essential for residents to be prepared for seismic events. Preparation includes having an emergency plan, creating an emergency kit, and knowing what actions to take during and after an earthquake. The ShakeAlert Earthquake Early Warning System plays a vital role in providing residents with crucial warning time to take necessary precautions, potentially reducing damage and casualties during an earthquake.