The quakes come as California sees the effects of an atmospheric river that has caused flash flooding, rescues, and landslides.

Underwater earthquakes can trigger massive phytoplankton blooms, linking deep-sea seismic activity to ocean life and carbon cycling.

There were at least six separate earthquakes that measured above a magnitude of 2.5 in an earthquake swarm in the San Ramon area on Friday night. No damage was reported, but locals were somewhat rattled by the frequency.

A wave of at least nine earthquakes ranging up to a preliminary magnitude of 4.0 struck southeast of San Ramon about 8 p.m. Friday, the U.S. Geological Survey said.

"Over that vast time, the rough edges and bends in the fault have been ground down," first author Eric Lindsey, a geoscientist at the University of New Mexico, said in a statement. "Because it is so smooth and straight, the earthquake rupture could travel very efficiently across a huge distance."

Residents in Amherstburg felt an earthquake on New Year’s Day. Earthquakes Canada has confirmed that a ‘lightly felt’ earthquake hit Amherstburg at 11:19 a.m. Thursday. The division of Natural Resources Canada stated that the quake had a magnitude of 2.0 MwN and the epicentre was located five kilometres below the town.

Earthquakes Canada says it registered three earthquakes in the same region near the Yukon-Alaska border within minutes of each other.

It is not unheard of for the ground to shake in Broken Hill, but what is unusual is the number of earthquakes recorded by Geoscience Australia this year.

Areas of Perthshire and the western Highlands, southern parts of Wales, and Yorkshire and Lancashire saw the most seismic activity, British Geological Survey data shows.

The area around San Ramon has recorded 91 quakes stronger than magnitude 2 over November and December, through Tuesday morning. That tally is the highest on record for the area for a two-month period, according to a Chronicle analysis of U.S. Geological Survey data.