Hayward Fault: Earthquake Risk, History & Live Activity
The Hayward Fault is a right-lateral strike-slip fault running about 74 kilometres along the east side of San Francisco Bay, through Oakland, Hayward, and Fremont. It is part of the wider San Andreas system, taking up a share of Pacific-North American plate motion at a slip rate of roughly 9 millimetres a year. Unusually, it creeps slowly at the surface between larger earthquakes.
How likely is a large earthquake?
UCERF3 (USGS, 2015) gives the San Francisco Bay region a 72 percent chance of a magnitude 6.7 or larger earthquake by 2043. The Hayward Fault is the single most likely source within that total; USGS studies have assigned the Hayward and Rodgers Creek system roughly a one-in-three chance of a major earthquake over a 30-year window, which is why it is often described as one of the most dangerous urban faults in the United States.
The concern is exposure as much as probability. The fault runs directly beneath densely built East Bay cities and beneath the water, gas, and transport lines that serve millions of people. Because part of the fault creeps, some strain is released steadily, but paleoseismic trenching shows that creep has not prevented large earthquakes in the past.
Live seismic activity near this fault
Counts include M2.5+ events — the smallest size USGS reports consistently worldwide.
| Magnitude | Time (UTC) | Depth | Location |
|---|---|---|---|
| M2.5 | Jul 29, 02:40 UTC | 4 km | 8 km ESE of Cloverdale, CA |
| M4.3 | Jul 29, 02:40 UTC | 6 km | 8 km ESE of Cloverdale, CA |
| M2.7 | Jul 27, 15:29 UTC | 1 km | 3 km ENE of The Geysers, CA |
| M2.8 | Jul 27, 15:29 UTC | 1 km | 3 km ENE of The Geysers, CA |
| M3.0 | Jul 27, 08:13 UTC | 5 km | 12 km ESE of Gilroy, CA |
| M2.5 | Jul 27, 06:29 UTC | 3 km | 3 km NW of The Geysers, CA |
| M2.5 | Jul 25, 11:31 UTC | 6 km | 3 km E of St. Helena, CA |
| M2.5 | Jul 24, 22:38 UTC | 5 km | 11 km ESE of Gilroy, CA |
| M2.7 | Jul 23, 00:52 UTC | 4 km | 2 km NNE of San Leandro, CA |
History
The Hayward Fault's defining historical event is the 1868 earthquake, and trenching has extended its record back several centuries.
- 1868 Hayward (M6.8) — one of the most destructive California earthquakes of the 1800s, felt from Napa to Santa Cruz.
- Early 1700s (paleoseismic, estimated M6.5 to 7) — the rupture immediately before 1868, dated from trench studies of offset soil layers.
- Older paleo-ruptures — the southern fault records roughly a dozen large earthquakes over the past 1,900 years, clustering near a mean interval of about 150 years.
Frequently asked questions
Is the Hayward Fault overdue?
The Hayward Fault last produced a major earthquake in 1868, and its average interval between large events is roughly 150 years, so the elapsed time now matches the long-term average. Scientists therefore describe it as being within, or slightly past, its typical recurrence window. That is a statement about averages from trenching, not a prediction of timing; the fault could rupture soon or stay quiet for years.
What would a big Hayward earthquake do?
The USGS HayWired scenario modelled a magnitude 7.0 on the Hayward Fault and estimated strong shaking across the East Bay, hundreds of thousands of people displaced, and prolonged disruption to water and transport because so many lifelines cross the fault. Its location beneath dense cities, rather than its magnitude alone, drives the projected impact.
Nearby regions
Live counts from the USGS earthquake feeds within 150 km of the fault. Magnitudes and depths are automated readings and may be revised. Not for emergency use.