A 4.5 magnitude earthquake that stuck in an area of the San Andreas fault system in Riverside County early Tuesday isn’t likely to be a precursor to a larger quake, but seismologists can’t be certain, a USGS official said Tuesday.
The temblor hit at 4:49 a.m. about 7 miles north of Cabazon with a preliminary depth of 8.5 miles, according to the USGS event page.
The epicenter was north of the 10 Freeway near the northern edge of the Morongo Indian Reservation.
The quake was initially reported as a 4.6 but was later downgraded to a 4.5.
About 50 aftershocks had been recorded as of 9:30 a.m., including a 3.2 magnitude aftershock that occurred about two minutes after the initial quake, Caltech staff seismologist Jennifer Andrews said at a news conference.
“This isn’t unusual for this area,” she added.
The quake struck near a complex part of the San Andreas fault, just east of the 5.9 magnitude North Palm Springs quake in 1986, Dr. Lucy Jones tweeted.
Historically, the area around Mt. San Gorgonio is the only part of southern San Andreas fault that produces smaller quakes. But the main San Andreas is not clearly defined here. At the surface, it disappears, covered by the Banning thrust fault.
— Dr. Lucy Jones (@DrLucyJones) May 8, 2018
USGS research seismologist Robert Graves said it was likely that the quake did not change the “state of stress” significantly enough to cause a larger earthquake.
“But we don’t know for sure,” Graves said.
The chances of a larger quake will be about 1 to 2 percent higher over the next week, Graves said.
No damage from the quake was reported, but many residents around Southern California experienced the temblor. The quake was felt by people as far away as Santa Clarita and San Diego, according to the U.S. Geological Survey.
A Banning resident named Grace who called into KTLA described lamps swinging from her ceiling and said her book case moved about an inch at her home.
“It’s scary. It did catch us by surprise. … It was a very good rumble,” Grace said.
In Yucaipa, Sherry Elsey said she felt a “violent thrust” and several items fell in her house.
In Los Angeles County, there were no reports of damage or injuries, county Fire Department Supervisor Rangel said.
Cabazon is located about 90 miles east of Los Angeles.
With all of the recent earthquake and volcanic activity in Hawaii, Graves was asked if the earthquake near Cabazon could be related.
“You could make an argument that it’s related in the grand scheme of things in terms of the global plate tectonics … but there’s no direct correlation between the activity that’s going on in Hawaii right now and today’s earthquake,” Graves said.
Graves hopes the quake will serve as a reminder for residents to prepare for a larger earthquake in the future.
“I would say with each day that passes that we don’t have a major earthquake, we’re one day closer to having a major earthquake,” Graves said.
