California was rattled by three earthquakes on Monday, April 20, with the largest quake measuring magnitude 4.7.
That earthquake was followed by two smaller quakes that measured magnitude 3.2 and 2.5. While the shaking was light, no structural damage or injuries have been reported so far.
The magnitude 4.7 earthquake struck about 52 kilometers west of Petrolia At about 3:41 a.m. on Monday. The quake originated at a depth of 13.6 kilometers.
According to the U.S. Geological Survey (USGS), the quake registered at Level III intensity, indicating light shaking. Additionally, only nine people submitted “felt reports” on the USGS website.
According to ShakeAlert, warnings were issued within seconds of the quake’s origin, with initial magnitude estimates between 3.6 and 3.8.
Cities exposed to the quake include Ferndale, Rio Dell, Fortuna, Hydesville, Pine Hills, Humboldt Hill, Eureka, Arcata, Ukiah, and McKinleyville. No damage was reported in these locations, according to the USGS.
More earthquakes than usual, known as aftershocks, are expected near the magnitude 4.7 mainshock.
So far, the USGS has mentioned that five aftershocks have been recorded, ranging from magnitude 3.6 to 2.3.
According to the forecast shared by the USGS, there is a probability of two or more aftershocks with a magnitude of 3 or higher within the coming week, with a combined chance of this happening to be around 16%.
The odds of aftershocks being magnitude 4 or above are only 2%, and for a harmful aftershock at 5 or higher is less than 1%. There are no chances of large quakes of 6 or 7 magnitudes occurring.
Meanwhile, the magnitude 3.2 earthquake occurred southeast of Johannesburg. The other measuring at magnitude 2.5 happened south-southwest of Maricopa.
Both were relatively weak and shallow and did not cause any significant vibrations to be felt, according to the USGS.
What Causes So Many Earthquakes in California?
The reason for earthquakes in California can be found in movements within the San Andreas Fault zone.
It causes the Pacific plate and the North American plate to pass each other, causing frequent earthquakes throughout California.
Safety Precautions
People living in the area are encouraged to practice necessary precautionary measures when an earthquake occurs.
Those who are inside their houses are advised to stay put, seek shelter from strong structures, cover themselves from head to toe, and stay away from windows and other heavy structures.
If people are outdoors, they need to relocate to safe areas. Those driving are instructed to park safely and wait out until the earthquake subsides.
