How large an earthquake can Hayward Fault produce?

The maximum magnitude potential compiled for Hayward Fault is M7.2. That figure comes from the length and width of the fault area that could rupture at once, calibrated against its historical and paleoseismic record. It is an upper bound on what the structure can do, not a forecast of the next event.

Is Hayward Fault overdue for an earthquake?

No fault is ever 'overdue' in the way the phrase suggests. Recurrence intervals are averages over a handful of past ruptures, not a schedule: the interval between two events on the same fault routinely varies by a factor of two or more. The elapsed time shown on this page is exactly that — how long it has been — and not a probability that a rupture is imminent.

How is the seismicity on this page selected?

Every earthquake listed sits within 25 km of the mapped trace of Hayward Fault, measured as the distance to the nearest fault segment rather than to a bounding box. Events on a neighbouring structure therefore do not appear here, even when they are geographically close. The slip rate of 9 mm/yr and the rupture history are compiled from the published literature.

All fault systems

Right-lateral strike-slip

Hayward Fault

San Francisco Bay Area, United States

Plate boundary: Pacific ↔ North American

Length: 119 km
Mₘₐₓ potential: M7.2
Slip rate: 9 mm/yr
Recurrence interval: ~150 years

Time elapsed since the last known rupture

105%

158 years have passed against an average interval of about 150 years. Recurrence on a real fault is not a clock — this is elapsed time, not a probability of rupture.

Locking depth

8–12 km

The depth range over which the fault is locked and accumulating elastic strain. Below it the rock creeps aseismically; above it, strain is released in earthquakes.

Historical rupture sequence

1868M6.8Hayward

Live seismicity within 25 km of the trace (last 30 days)

Loading seismicity along this fault trace…

Frequently Asked Questions (FAQ)

Verified scientific, operational, and emergency protocols

Hayward Fault is a right-lateral strike-slip system running roughly 119 km through San Francisco Bay Area, United States. The kinematics describe how the two sides move relative to each other, which governs both the shaking a rupture produces and whether it can displace the sea floor.