On Monday morning, around 30 minor earthquakes erupted in a swarm near the Geysers geothermal field south of Clear Lake. The day before, seven quakes rattled Sonoma County, including a 4.0 quake. The recent uptick isn't out of the ordinary, according to U.S. Geological Survey seismologist Susan Hough.

A magnitude 4.0 earthquake Sunday afternoon three miles from Santa Rosa was followed a few minutes later by magnitude 3.1 and 3.4 temblors.

Two small earthquakes were recorded near Concrete on Monday morning, according to the U.S. Geological Survey. The first earthquake, measured at magnitude 2.6, was recorded at 7:06 a.m. about 4 kilometers west-southwest of Concrete. The USGS reported the quake occurred at a depth of about 5.5 kilometers beneath the surface.

Aftershocks have been recorded for both earthquakes. On Dec. 8, Japanese authorities warned an even more powerful earthquake could strike within the next week and called on residents from the northernmost island of Hokkaido down to Chiba prefecture, east of Tokyo, to be on high alert.

A swarm of at least six earthquakes reaching up to magnitude 2.9 rattled San Ramon near San Francisco, the U.S. Geological Survey reports.

Japan’s Meteorological Agency said a powerful earthquake hit off the Japanese northern coast Monday, triggering a tsunami alert.

Several earthquakes, the largest measured at magnitude-3.3, were reported Thursday morning in Ventura County. The earthquakes were centered near Fillmore, about 25 miles northeast of Ventura. Shaking was reported in Fillmore, Moorpark, Ventura and Santa Paula.

A shake alert went out over the U.S. Geological Survey's early warning system on Dec. 4, warning that a 5.9 earthquake near Carson City in western Nevada could produce heavy shaking in the region. But moments later, the survey announced the alert, which was sent to people as far west as San Francisco, was a false alarm.

The federal government and earthquake experts blamed a technical glitch for the alert that sent warnings hundreds of miles away last week.

California's seismic risk is increasing with supershear earthquakes, which are faster and more destructive than typical earthquakes.

Glacial earthquakes are a special type of earthquake generated in cold, icy regions. First discovered in the Northern Hemisphere more than 20 years ago, these quakes occur when huge chunks of ice fall from glaciers into the sea.

New research demonstrates that ML can also predict metre-scale laboratory earthquakes, suggesting that, when scaled, similar approaches could offer early warning times from weeks to decades for large natural quakes.