M3.3 earthquake 3 km ESE of Larkfield-Wikiup, California, United States

Name: M3.3 earthquake 3 km ESE of Larkfield-Wikiup, California, United States
Start: 2026-09-03T17:33:27.320Z
End: 2026-09-03T17:33:27.320Z
Location: 3 km ESE of Larkfield-Wikiup, California, United States

A magnitude 3.3 earthquake struck 3 km ESE of Larkfield-Wikiup, California, United States at 10:33 local time (17:33 UTC) on 3 Sept 2026, at a depth of 9 km, according to USGS.

1843 reports to USGS “Did You Feel It?”

Data: USGS · updated 2026-09-10 19:53 UTC · reviewed

Magnitude: 3.3minor
moment magnitude (mw)
Depth: 8.8 km
Status: Reviewed
Origin time: 2026-09-03 17:33:27 UTC; Local: 3 Sept 2026, 10:33:27 (America/Los Angeles)
Epicentre: 38.501° N, 122.715° W

Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map

Nearby places

Distance and estimated shaking at nearby places
Place	Distance	Est. shaking
Larkfield-WikiupCalifornia, United States · pop. 8,884	3 km	IVLight
Santa RosaCalifornia, United States · pop. 178,127	7 km	IIIWeak
WindsorCalifornia, United States · pop. 27,464	11 km	IIIWeak
Rohnert ParkCalifornia, United States · pop. 42,407	18 km	IIIWeak
Agua CalienteCalifornia, United States · pop. 27,090	28 km	IIWeak
San FranciscoCalifornia, United States · pop. 827,526	85 km	INot felt
OaklandCalifornia, United States · pop. 419,267	87 km	INot felt
SacramentoCalifornia, United States · pop. 524,943	107 km	INot felt

Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more. Likely felt out to about 21 km.

Every agency's solution

Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · NC, which has been reviewed by an analyst.

Agency	Magnitude	Depth	Epicentre	Time offset	Status
USGS · NCheadlineNorthern California Seismic System via U.S. Geological Survey	3.3 mw	8.8 km	38.50° N, 122.72° W	–	Reviewed

How big was it?

Often felt by people at rest close to the epicentre, rarely causes damage.

It released roughly the energy of 1.5 t of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 9 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

Compare M3.3 with M2.3

M3.3 releases about 36× the energy of M2.3, and its waves are about 11× taller on a seismogram. Energy: 1.5 t of TNT vs 43 kg of TNT.

Each square is the energy of one M2.3. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

12 later earthquakes within 30 km; the largest was M2.6 12 days ago. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M3.3

12 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).

Did you feel it?

Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.

Reports close 14 days after an earthquake.

Reports on SeismoAtlas

No reports yet.

USGS “Did You Feel It?” has 1843 reports: add yours at USGS.

Event id nc75429272. First recorded here 28 Sept 2026, 17:32:13 UTC. Solutions: USGS · NC (usgs:nc75429272). Cite as: SeismoAtlas, “M3.3 earthquake 3 km ESE of Larkfield-Wikiup, California, United States”, https://seismoatlas.com/earthquake/nc75429272-m3-3-earthquake-3-km-ese-of-larkfield-wikiup-california-united-states, data from USGS.

JSON: /api/v1/events/nc75429272. SeismoAtlas is not an official warning service.

Time after mainshock (hours)	Magnitude	Depth (km)
296.12	2.6	10
440.77	1.5	5
454.72	1.1	2
465.22	1.2	0
472.51	1.0	7
494.95	1.7	6
515.12	0.7	2
530.75	1.2	2
542.94	1.1	2
548.37	1.1	2
564.62	1.2	2
591.34	1.4	5