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M3.5 Earthquake near Cayey, Puerto Rico — 28 December 2024

A minor earthquake of magnitude 3.5 was recorded near Cayey, Puerto Rico on , with an epicentre 4 km east-southeast of G. L. Garcia, at a focal depth of 24.0 km. It ranked as the 3rd strongest of 45 earthquakes recorded in Puerto Rico in the preceding 30 days.

3.5 Minor

Time (UTC): 2024-12-28 04:03:08

Time (your timezone): —

Magnitude: 3.5 (minor)

Focal depth: 24.0 km (shallow)

Epicentre: 18.1098, -66.0656

Location: 4 km ESE of G. L. Garcia, 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 3.5 earthquake radiates roughly 2.3 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 188, 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 18.1098, -66.0656 — 4 km east-southeast of G. L. Garcia. The closest other recorded event was a magnitude 2.1 earthquake 13 km west-southwest of here on 30 July 2026.

Why the 24 km depth matters

At 24 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 M3.5 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

44 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.

83 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 M3.5 event released about 1,799 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 December 2024 worldwide record, and of earthquakes in Puerto Rico during December 2024. 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 is a magnitude 3.5 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 3.5 earthquake radiates roughly 2.3 tons of TNT equivalent in seismic energy.

How deep was the earthquake near Cayey?

At 24 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 M3.5 earthquake near Cayey felt?

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.

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 M3.5 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?

44 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 Cayey?

83 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 M3.5 event released about 1,799 times less energy than that event.