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M1.3 Earthquake near Mammoth, United States — 07 September 2026

A micro earthquake of magnitude 1.3 was recorded near Mammoth, United States on , with an epicentre 26 km south-southwest of Mammoth, at a focal depth of 4.8 km. It ranked as the 4371st strongest of 7851 earthquakes recorded in the United States in the preceding 30 days.

1.3 Micro

Time (UTC): 2026-09-07 19:19:49

Time (your timezone): —

Magnitude: 1.3 (micro)

Focal depth: 4.8 km (shallow)

Epicentre: 44.7452, -110.7850

Location: 26 km SSW of Mammoth, Wyoming

Country: United States

USGS link to NOAA tsunami information: Not linked

Review status: Reviewed

Source: USGS event page

How strong was this earthquake?

Micro earthquakes are almost never felt at the surface and are recorded only by seismographs.

A magnitude 1.3 earthquake radiates roughly 1.2 kg of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 25, 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 11:56 local solar time at the epicentre, during the morning.

This event was shallower than 59% of the 154,586 earthquakes recorded in the United States in our catalogue and stronger than 48% of them.

Where was the epicentre?

The epicentre was located at 44.7452, -110.7850 — 26 km south-southwest of Mammoth. The closest other recorded event was a magnitude 1.8 earthquake 1 km north of here on 08 September 2026.

The nearest other settlements in our records are Big Sky (65 km northwest), Cooke City (71 km east-northeast), Cameron (76 km west) and Drummond (87 km south-southwest).

Why the 5 km depth matters

At 5 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, events this small are usually detected by instruments rather than people. 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 M1.3 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

27 further earthquakes have been recorded within about 150 km of the epicentre in the 1 day since this event, the largest of them magnitude 2.8.

0 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 3.9 event near Mammoth on 29 January 2025. This M1.3 event released about 10,116 times less energy than that event.

895 earthquakes have been recorded within 100 km of this epicentre in the past year, 38 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 1 earthquakes worldwide

Questions about this earthquake

How strong was the earthquake near Mammoth?

It measured magnitude 1.3 — a micro earthquake. A magnitude 1.3 earthquake radiates roughly 1.2 kg of TNT equivalent in seismic energy.

How deep was the earthquake near Mammoth?

The focus was 5 km below the surface, which counts as shallow.

Was the Mammoth earthquake felt at the surface?

At magnitude 1.3 and a focal depth of 5 km, shaking would have been concentrated near the epicentre.

When did the earthquake near Mammoth happen?

07 September 2026 at 19:19 UTC.

Was there a tsunami?

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

Have there been aftershocks?

27 further earthquakes have been recorded within about 150 km of the epicentre in the 1 day since this event, the largest of them magnitude 2.8.

How often do earthquakes happen near Mammoth?

0 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 3.9 event near Mammoth on 29 January 2025. This M1.3 event released about 10,116 times less energy than that event.