Campus Alert Archive
UC Berkeley

2:56 AM Magnitude 4.3: The Hayward Fault Quake With Its Epicenter Right Under UC Berkeley

CAearthquakeemergency notificationmedium confidence
Confirmed Threat

At 2:56 AM PDT on Monday, September 22, 2025, a magnitude 4.3 earthquake struck with its epicenter on Piedmont Avenue and Dwight Way — just blocks south of UC Berkeley's main campus. The quake, one of the 50 largest the Bay Area has experienced since the 1906 San Francisco earthquake, was felt across Northern California. UC Berkeley sent its first alert at 3:07 AM through its newly-launched Safety App — the first major test of the system rolled out at the start of the fall semester.

Alerts
1
Response
—
Killed
0
Injured
0
Institution
University of California, Berkeley
Public R1 · CA
~45,000 studentsRaveUC Berkeley Safety App
Confirmed Timeline

Alert Sequence

1 message in sequence

Some alert texts below are approximate reconstructions from news coverage, not confirmed verbatim transcripts. Reconstructed texts are shown in italic with a dashed border. Verified verbatim texts have a solid border and are marked accordingly.

INITIAL ALERTPush
Approximate reconstructionReconstructed from Berkeley Scanner reporting that confirmed UC Berkeley sent a Safety App alert at 3:07 AM PDT on September 22, 2025247 chars
UC Berkeley Safety Alert: A magnitude 4.3 earthquake occurred at 2:56 AM near campus. If you are inside, check for injuries and damage. Be prepared for aftershocks. Drop, Cover, and Hold On if shaking resumes. Monitor oem.berkeley.edu for updates.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

Sent at 3:07 AM PDT on September 22, 2025 — approximately 11 minutes after the 2:56 AM magnitude 4.3 earthquake
This was one of the first major real-world uses of UC Berkeley's new Safety App, rolled out for fall 2025 to replace public WarnMe email blasts
The Berkeley Scanner reported this alert as the central notification many students and staff received before sunrise; the Cal student paper documented widespread reactions including ceiling debris, fallen objects, and confused students texting in dorm group chats
Context

Background

UC Berkeley sits directly atop the Hayward Fault — one of the most dangerous faults in California, which the USGS has estimated has a 33% likelihood of producing a magnitude 6.7 or greater earthquake by 2043. The fault runs visibly through campus and directly beneath California Memorial Stadium. At 2:56 AM PDT on September 22, 2025, a magnitude 4.3 earthquake struck with its epicenter on Piedmont Avenue at Dwight Way — only blocks from the heart of campus. The quake was felt across the Bay Area and was among the 50 largest the region has experienced since the 1906 San Francisco earthquake. It triggered the California ShakeAlert early warning system, sending warnings to smartphones across Northern California seconds before shaking arrived. UC Berkeley issued its first emergency notification at 3:07 AM through the newly-launched UC Berkeley Safety App, which had been rolled out for fall 2025 as the university shifted from public WarnMe email blasts to a push-notification-first model. Seismologists from the UC Berkeley Seismology Lab warned that continuing stress accumulation on the Hayward Fault makes a much larger quake increasingly likely, though the September 22 event was not a definitive foreshock. A magnitude 3.0 aftershock struck almost exactly under UC Berkeley's Calvin Lab on October 16, 2025 — the morning of the annual Great Berkeley ShakeOut earthquake drill.
Analysis

Key Findings

The September 22, 2025 magnitude 4.3 quake had its epicenter just south of UC Berkeley campus on Piedmont Avenue at Dwight Way — making it among the closest recorded quakes to the campus core
UC Berkeley's first alert went out at 3:07 AM PDT — approximately 11 minutes after the 2:56 AM quake — through the newly-launched Safety App
This was one of the first major real-world tests of UC Berkeley's new push-notification-first alert system, rolled out for fall 2025 to replace public WarnMe emails
The Hayward Fault runs directly under UC Berkeley's Memorial Stadium and intersects the campus; USGS estimates a 33% likelihood of M6.7+ on the fault by 2043
A magnitude 3.0 aftershock struck almost exactly under UC Berkeley's Calvin Lab on October 16, 2025 — the morning of the Great Berkeley ShakeOut drill
Outcome
No injuries or significant structural damage reported. The Hayward Fault, which runs directly under UC Berkeley's Memorial Stadium and California Memorial Stadium, was identified by seismologists as the likely source. Multiple aftershocks followed in the days afterward, including a magnitude 3.0 aftershock on October 16, 2025.
Provenance

Sources

  1. News
    Update: Magnitude 4.3 earthquake jolts UC Berkeley - The Berkeley Scanner
    berkeleyscanner.com
  2. Official
    M 4.3 - 2 km ESE of Berkeley, CA - USGS
    earthquake.usgs.gov
  3. News
    Last Night's 4.3M Berkeley Earthquake Among 50 Largest Bay Area Has Experienced Since Great 1906 San Francisco Quake - Hoodline
    hoodline.com
  4. News
    UC Berkeley cuts public emails amid safety alert overhaul - The Berkeley Scanner
    berkeleyscanner.com
  5. Official
    UC Berkeley Seismology Lab
    earthquakes.berkeley.edu
  6. Student Paper
    3.0 magnitude aftershock hits UC Berkeley - The Daily Californian
    dailycal.org
Tags
earthquakepublic-r1californiahayward-faultshakealertsafety-apppredawnuc-systembay-areaseismic
Added May 2026Updated May 2026Via ingestion