Sunday around 6:44 a.m., a 3.8 magnitude earthquake shook the ground 31 miles outside of Chico — which was followed by a smaller 3.2 magnitude tremor south of Gilroy at 11:05 a.m. this morning.
According to the United States Geological Survey (USGS), a pair of notable earthquakes rattled parts of NorCal Sunday, each of the quakes happening before noon. Though comparatively small and quite common — earthquakes that register between 2.5 and 4.5 on the Richter scale number annually some 30,000 across the world — these like-magnitude earthquakes are capable of being felt tens of miles away and can cause slight damage.
When out in the field there arose such a clatter,— USGS Earthquakes (@USGS_Quakes) December 24, 2020
a seismometer captured what was the matter.
Seismometers record earthquakes and anything else that makes the ground shake, including large hoofed creatures.https://t.co/49GCp5scxH
Sunday's larger earthquake in NorCal was detected around 9 miles east of Willows, a small city an hour north of Sacramento. The USGS's "ShakeMap" shows "light" vibrations from the earthquake's epicenter radiated over fifty miles in each direction — making the tremor capable of being felt by Yuba City residents over fifty miles away.
The less sizable, more local quake originated 2 miles west of San Juan Bautista, 14 miles outside Gilroy; the tremor was only strong enough to produce "weak" vibrations that were noticeable about 30 miles in either direction of its epicenter.
Both earthquakes produced no damage but added to a year of increased geological activity in California — particularly along otherwise sleepy fault lines that have become more lively as of late.
Image: Example of seismometer printing. (Courtesy of Getty Images via kickers)