A 4.7-magnitude earthquake struck near the Utah-Wyoming border Thursday morning and shook buildings in Salt Lake City, according to the US Geological Survey (USGS). No earthquake damage was reported.
The epicenter of the earthquake was located about 25 miles south of Evanston, Wyoming, at a depth of 13.4 miles. Nearly 1,600 people reported feeling the tremor, Newsweek reported.
It happened just two days after a 4.9 magnitude earthquake hit Indio, California. Tremors were felt throughout Southern California, including San Diego, Palm Springs, Temecula and Riverside.
The earthquake struck the area shortly before 9:00 PM EDT on Monday at a shallow depth of 3 kilometers. The epicenter was located approximately 12 miles (19 km) north-northeast of India, California.
The earthquake was initially reported as a magnitude 5.1 event, but was later downgraded to 4.9, according to the USGS.
California lies in one of the most active seismic zones in the world. The state is crossed by more than 500 known active faults, including the famous San Andreas Fault system. This fault has produced large earthquakes in the past and continues to pose a risk of future seismic activity.
Do small earthquakes happen often in California?
Although the recent Petrolia earthquake was small, California experiences frequent seismic activity in both northern and southern regions. These range from very small tremors that go unnoticed to mild events with magnitudes close to 4.0 or greater.
Clusters or swarms of small earthquakes were reported in parts of northern California, including the San Ramon and Bay Area. These are dozens of smaller earthquakes occurring within a short period of time. Such swarms do not usually indicate that a major earthquake is imminent, but are common in areas with complex fault systems.
Low-level earthquakes like the 2.3 event near Petrolia help scientists observe how faults behave and how stress builds up underground. Seismologists study these smaller tremors to map fault lines, understand underground structures, and improve earthquake monitoring.
How do early warning systems help?
California uses early warning systems like ShakeAlert and statewide preparedness programs that rely on dense networks of seismic sensors. These systems detect earthquakes as they begin and can send alerts seconds before stronger tremors reach an area.
Early warning systems do not predict earthquakes. Instead, they detect seismic activity in real time and send alerts to phones and critical infrastructure. Those extra few seconds can allow people to “DROP, COVER and HOLD,” a safety procedure recommended by emergency planners to reduce the risk of injury during an earthquake.
