Earthquake.now

M3.4 Earthquake near Brentwood, United States — 12 September 2026

A minor earthquake of magnitude 3.4 was recorded near Brentwood, United States on , with an epicentre 9 km southwest of Brentwood, at a focal depth of 17.9 km. It ranked as the 240th strongest of 7785 earthquakes recorded in the United States in the preceding 30 days.

3.4 Minor

Time (UTC): 2026-09-12 07:25:55

Time (your timezone): —

Magnitude: 3.4 (minor)

Focal depth: 17.9 km (shallow)

Epicentre: 37.8728, -121.8000

Location: 9 km SW of Brentwood, CA

Country: United States

USGS link to NOAA tsunami information: Not linked

Review status: Reviewed

Source: USGS event page

How strong was this earthquake?

Minor earthquakes in this range are felt by people close to the epicentre as a brief jolt or rattle, but they very rarely cause any damage.

A magnitude 3.4 earthquake radiates roughly 1.7 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 192, which is below the USGS threshold of more than 600 for its significant-earthquake list. The ranking combines magnitude with available Did You Feel It responses and PAGER alert level; it is not a direct measurement of damage.

What the magnitude scale actually measures →

When it happened locally

That is about 23:18 local solar time at the epicentre, late at night.

This event was deeper than 84% of the 155,363 earthquakes recorded in the United States in our catalogue and stronger than 98% of them.

Where was the epicentre?

The epicentre was located at 37.8728, -121.8000 — 9 km southwest of Brentwood. The closest other recorded event was a magnitude 1.5 earthquake 24 km southwest of here on 11 September 2026.

The nearest other settlements in our records are Alamo (24 km west-southwest), Albany (44 km west), Alameda (47 km west-southwest) and American Canyon (56 km west-northwest).

Why the 18 km depth matters

At 18 km this was a shallow earthquake. Shallow events release their energy close to the surface, so for a given magnitude they produce noticeably stronger shaking — and more damage — than deeper ones. Roughly three quarters of all earthquakes worldwide occur at shallow depths.

This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size may be noticed locally, especially close to the epicentre. Its shallow focus makes stronger surface shaking more likely than for a deeper event of the same magnitude.

Read more on how focal depth changes what you feel →

What does the tsunami information flag mean?

The USGS record does not carry a link to NOAA tsunami information. That field is not an all-clear and does not state whether a tsunami occurred. In this case, a damaging tsunami would be less likely because at M3.4 it falls below the magnitude 6.5 threshold that generally applies before a submarine earthquake displaces enough water to generate a damaging tsunami; it occurred inland rather than beneath the sea floor. For an active coastal alert, use tsunami.gov or your local warning authority.

How earthquakes generate tsunamis, and what the alert levels mean →

Aftershocks and local seismic history

1 further earthquakes have been recorded within about 150 km of the epicentre since this event was recorded, the largest of them magnitude 0.7.

21 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.6 event near Redwood Valley on 24 June 2026. This M3.4 event released about 2,213 times less energy than that event.

1704 earthquakes have been recorded within 100 km of this epicentre in the past year, 110 of them in the past 30 days.

How long aftershock sequences last, and how large they get →

Where this event sits in the record

This earthquake is part of the September 2026 worldwide record, and of earthquakes in the United States during September 2026. Browse the full monthly archive to compare periods.

Nearest recorded earthquakes to this epicentre

Other recent earthquakes in the United States

All recorded earthquakes in the United States →

Other magnitude 3 earthquakes worldwide

All magnitude 3 earthquakes →

Questions about this earthquake

How strong was the earthquake near Brentwood?

It measured magnitude 3.4 — a minor earthquake. A magnitude 3.4 earthquake radiates roughly 1.7 tons of TNT equivalent in seismic energy.

How deep was the earthquake near Brentwood?

The focus was 18 km below the surface, which counts as shallow.

Was the Brentwood earthquake felt at the surface?

At magnitude 3.4 and a focal depth of 18 km, shaking would have been concentrated near the epicentre.

When did the earthquake near Brentwood happen?

12 September 2026 at 07:25 UTC.

Was there a tsunami?

No. The USGS record carries no tsunami-information link for this event.

Have there been aftershocks?

1 further earthquakes have been recorded within about 150 km of the epicentre since this event was recorded, the largest of them magnitude 0.7.

How often do earthquakes happen near Brentwood?

21 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.6 event near Redwood Valley on 24 June 2026. This M3.4 event released about 2,213 times less energy than that event.