Earthquake.now

M0.4 Earthquake near Holtville, United States — 28 August 2026

A micro earthquake of magnitude 0.4 was recorded near Holtville, United States on , with an epicentre 45 km northeast of Holtville, at a focal depth of -0.2 km. It ranked as the 7095th strongest of 7761 earthquakes recorded in the United States in the preceding 30 days.

0.4 Micro

Time (UTC): 2026-08-28 17:36:43

Time (your timezone): —

Magnitude: 0.4 (micro)

Focal depth: -0.2 km (shallow)

Epicentre: 33.0522, -114.9980

Location: 45 km NE of Holtville, CA

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 0.4 earthquake radiates roughly 0.06 kg of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 2, 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 →

Where was the epicentre?

The epicentre was located at 33.0522, -114.9980 — 45 km northeast of Holtville. The closest other recorded event was a magnitude 1.3 earthquake 1 km northeast of here on 26 August 2026.

Why the -0 km depth matters

At -0 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 M0.4 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 in the 3 hours since this event, the largest of them magnitude 0.7.

22 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 6.0 event near San Diego Country Estates on 14 April 2025. This M0.4 event released about 251.2 million times less energy than that event.

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

Where this event sits in the record

This earthquake is part of the August 2026 worldwide record, and of earthquakes in the United States during August 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 0 earthquakes worldwide

Questions about this earthquake

How strong is a magnitude 0.4 earthquake?

Micro earthquakes are almost never felt at the surface and are recorded only by seismographs. A magnitude 0.4 earthquake radiates roughly 0.06 kg of TNT equivalent in seismic energy.

How deep was the earthquake near Holtville?

At -0 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.

Was the M0.4 earthquake near Holtville felt?

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.

What does the USGS tsunami field mean for this event?

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 M0.4 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.

Have there been aftershocks?

1 further earthquakes have been recorded within about 150 km of the epicentre in the 3 hours since this event, the largest of them magnitude 0.7.

How often do earthquakes happen near Holtville?

22 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 6.0 event near San Diego Country Estates on 14 April 2025. This M0.4 event released about 251.2 million times less energy than that event.