133 km N of San Juan, 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 29 km (18 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 10 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 16,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 730× the energy of this one
3. Magna, Utah 2020 M 5.7 520× the energy of this one
4. This earthquake M 3.9 about 10 tons of TNT
5. Around the size people start to feel M 3.0 this one released 22× more

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 4.4 on 2016-10-23 — about 5.8 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

1. 5.1 92 km N of Suárez, Puerto Rico · 47 km SSE of this epicentre Aug 14, 2009
2. 5.0 113 km N of Brenas, Puerto Rico · 50 km WSW of this epicentre Nov 23, 2008

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 19.6561, -65.8823. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.8 127 km N of San Juan, Puerto Rico 11:55 UTC
2. 3.4 104 km N of San Juan, Puerto Rico 05:34 UTC
3. 3.9 144 km N of San Juan, Puerto Rico 22:46 UTC
4. 3.4 125 km N of San Juan, Puerto Rico 05:17 UTC
5. 3.8 158 km N of San Juan, Puerto Rico 23:52 UTC
6. 3.6 121 km N of Suárez, Puerto Rico 11:03 UTC
7. 3.6 136 km N of Suárez, Puerto Rico 05:47 UTC
8. 3.4 122 km NNE of Vieques, Puerto Rico 18:16 UTC
9. 3.7 126 km NNE of Vieques, Puerto Rico 04:30 UTC
10. 3.8 140 km NNE of Suárez, Puerto Rico 08:14 UTC
11. 3.6 Puerto Rico region 17:49 UTC
12. 3.8 138 km NNE of Suárez, Puerto Rico 06:09 UTC
13. 3.9 141 km N of Suárez, Puerto Rico 23:52 UTC
14. 4.2 123 km N of Suárez, Puerto Rico 18:43 UTC
15. 3.7 135 km N of Suárez, Puerto Rico 16:31 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:32 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.