Wave of small earthquakes hits California just days after previous wave

Graeme Massie
·2 mins read
Swarm of four small earthquakes rattled northern California leaving residents worried a big one could be on its way. (iStock)
Swarm of four small earthquakes rattled northern California leaving residents worried a big one could be on its way. (iStock)

A wave of four small earthquakes rattled northern California leaving residents concerned a much larger one might be on its way.

The wave of earthquakes ranged from a 1.3 magnitude to a 3.3 magnitude and struck within an hour around the northern edge of the Calaveras Reservoir, near Milpitas.

The US Geological Survey says it was the second time in three days that multiple quakes hit the area.

Experts said a 2.7 hit at 8.16am, followed by a 3.0 and a 1.3 ten minutes later, before the 3.3 at 9.02am on Tuesday.

The reservoir is located less than 20 miles from where Tesla is based in Fremont, California, and sits on the Calaveras fault system.

The latest wave comes after a string of 20 quakes hit the same area in August.

“The Calaveras fault, in particular, has fairly frequent what we call “earthquake swarms”,” said Elizabeth Cochran, a seismologist with the US Geological Survey.

“These are sets of events that are relatively low magnitude, where you have lots of events happening over a period of days to weeks.”

Ms Cochran said the frequency was due to the ground’s “weak material almost like talcum powder”, which caused the fault to move slowly but consistently.

There were no reports of injuries or damage but following the earlier earthquakes on Sunday, but it left residents hoping they were not in store for a big quake in 2020.

“2020 has been rough already, so it’s going to be another curveball thrown at us,” said Santa Clara resident Jason Mayor.

The Bay Area is famously located along the extremely volatile “Ring of Fire”, which stretches around the Pacific Ocean.

Along much of the Ring the earth’s tectonic plates overlap and experts say that earthquakes happen when an underneath plate scrapes against or is pushed down by the plate above.