San Franciscans and other Bay Area locals were shaken awake by an unusually powerful (and nearby) earthquake late Monday night that occurred along a particularly dangerous fault line.
Insomniacs and those still on a high from this year’s Portola festival were rattled into alertness Monday, September 22nd, at nearly 3 a.m. after a 4-plus magnitude struck just miles away.
Good morning Bay Area CA! Did you feel the M4.6 quake about 1 mile southeast of Berkeley at 2:56 am? The #ShakeAlert system was activated. See: https://t.co/qyeN0fNvQa @CAGeoSurvey @Cal_OES @USGS_Quakes @BerkeleySeismo @CaltechSeismo pic.twitter.com/WBRsHju694
— USGS ShakeAlert (@USGS_ShakeAlert) September 22, 2025
The United States Geological Survey (USGS) initially recorded the 4.6 magnitude tremor, which sent “light” to “moderate” shakes across the San Francisco Bay Area and was later downgraded to a 4.4 magnitude rating, was one of the nearest epicentered large quakes the region has experienced over the past two years.
USGS recorded the epicenter at Berkeley at a depth of around five miles below the Earth’s surface. Initial reports indicate that vibrations were felt as far away as Santa Rosa, although the shaking was almost unpredictable.
Thankfully, the National Oceanic and Atmospheric Association (NOAA) delivered no tsunami threats or warnings, and the earthquake’s strength, though jolting, likely produced no significant damage.
The earthquake’s epicenter was recorded right along the Hayward Fault Line — one of the three major fault lines in Northern California that are expected to produce the next “big one” by 2050. The Hayward Fault is universally considered the most at-risk; geologists hypothesize that a strong earthquake along the Hayward Fault could be damaging, and the Hayward Fault could potentially become larger if it happens within close proximity of the Rogers Creek Fault.
No aftershocks from the tremor have been recorded by USGS as of publication, but there’s a 35% of an over 3.0 magnitude aftershock happening sometime within the week.
