77 km NNW of San Antonio, Puerto Rico

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 6 km (4 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

How big was it?

This earthquake released about 700 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
2. Magna, Utah 2020 M 5.7 15,000× the energy of this one
3. Around the size people start to feel M 3.0 1.4× the energy of this one
4. This earthquake M 2.9 about 700 lb of TNT

Energy from the Gutenberg–Richter relation (log₁₀E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

For this area

The largest earthquake within 50 km since 2016 was M 6.0 on 2019-09-24 — about 43,000 times the energy of this one.

Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:

1. 7.7 45 km N of San Antonio, Puerto Rico · 33 km SSE of this epicentre Jul 29, 1943
2. 6.8 94 km NE of Punta Cana, Dominican Republic · 49 km W of this epicentre Jul 27, 1917
3. 6.4 61 km N of Hatillo, Puerto Rico · 49 km ESE of this epicentre Jan 13, 2014
4. 6.0 93 km NNW of San Antonio, Puerto Rico · 15 km NNW of this epicentre Jul 27, 1917
5. 6.0 81 km N of Isabela, Puerto Rico · 35 km E of this epicentre Jul 30, 1943

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 19.1801, -67.2506. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

56 earthquakes have been recorded within 50 km since this one.

1. 2.9 69 km N of Isabela, Puerto Rico 03:44 UTC
2. 2.9 72 km N of San Antonio, Puerto Rico 03:33 UTC
3. 2.7 50 km NNW of San Antonio, Puerto Rico 02:13 UTC
4. 2.6 70 km NNW of San Antonio, Puerto Rico 01:28 UTC
5. 2.8 66 km NNW of San Antonio, Puerto Rico 00:18 UTC
6. 3.0 90 km NNW of San Antonio, Puerto Rico 00:14 UTC
7. 3.3 49 km N of San Antonio, Puerto Rico 00:11 UTC
8. 3.0 74 km NNW of San Antonio, Puerto Rico 00:04 UTC
9. 2.7 62 km N of Isabela, Puerto Rico 23:47 UTC
10. 3.0 87 km NNW of San Antonio, Puerto Rico 22:13 UTC
11. 3.2 70 km NNW of San Antonio, Puerto Rico 21:19 UTC
12. 3.1 92 km NNW of San Antonio, Puerto Rico 17:43 UTC
13. 3.2 75 km N of San Antonio, Puerto Rico 15:16 UTC
14. 2.7 58 km N of San Antonio, Puerto Rico 13:08 UTC
15. 2.8 61 km N of Isabela, Puerto Rico 11:31 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:21 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

• The official USGS event page — the source of record for every value above
• Did you feel it? Report it to USGS — reports go to USGS, not to us
• ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.