Earthquake.now

M3.3 Earthquake near San Juan, Puerto Rico — 21 April 2026

A minor earthquake of magnitude 3.3 was recorded near San Juan, Puerto Rico on , with an epicentre 107 km north of San Juan, at a focal depth of 29.6 km. It ranked as the 12th strongest of 157 earthquakes recorded in Puerto Rico in the preceding 30 days.

3.3 Minor

Time (UTC): 2026-04-21 18:02:39

Time (your timezone): —

Magnitude: 3.3 (minor)

Focal depth: 29.6 km (shallow)

Epicentre: 19.4312, -66.0048

Location: 107 km N of San Juan, Puerto Rico

Country: Puerto Rico

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 3.3 earthquake radiates roughly 1.5 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 172, 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 13:38 local solar time at the epicentre, around midday.

This event was deeper than 85% of the 4,023 earthquakes recorded in Puerto Rico in our catalogue and stronger than 91% of them.

Where was the epicentre?

The epicentre was located at 19.4312, -66.0048 — 107 km north of San Juan. The closest other recorded event was a magnitude 3.1 earthquake 62 km southwest of here on 08 October 2026.

The nearest other settlements in our records are Brenas (111 km south-southwest), Cataño (112 km south), Candelaria Arenas (116 km south-southwest) and Campanilla (117 km south-southwest).

Why the 30 km depth matters

At 30 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 M3.3 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

45 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 3.7.

86 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 Cruz Bay on 04 May 2025. This M3.3 event released about 2,723 times less energy than that event.

347 earthquakes have been recorded within 100 km of this epicentre in the past year, 32 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 April 2026 worldwide record, and of earthquakes in Puerto Rico during April 2026. Browse the full monthly archive to compare periods.

Nearest recorded earthquakes to this epicentre

Other recent earthquakes in Puerto Rico

All recorded earthquakes in Puerto Rico →

Other magnitude 3 earthquakes worldwide

All magnitude 3 earthquakes →

Questions about this earthquake

How strong was the earthquake near San Juan?

It measured magnitude 3.3 — a minor earthquake. A magnitude 3.3 earthquake radiates roughly 1.5 tons of TNT equivalent in seismic energy.

How deep was the earthquake near San Juan?

The focus was 30 km below the surface, which counts as shallow.

Was the San Juan earthquake felt at the surface?

At magnitude 3.3 and a focal depth of 30 km, shaking would have been concentrated near the epicentre.

When did the earthquake near San Juan happen?

21 April 2026 at 18:02 UTC.

Was there a tsunami?

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

Have there been aftershocks?

45 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 3.7.

How often do earthquakes happen near San Juan?

86 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 Cruz Bay on 04 May 2025. This M3.3 event released about 2,723 times less energy than that event.