QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9md

Mona Passage

Yes. A magnitude 3.9 earthquake was recorded in Mona Passage, 16 km (10 mi) SE of Mayagüez, PR, at 11:13 am AST on 22 January 2023 (15:13 UTC), 18 km deep. 37 people have reported feeling it to USGS.

16 km (10 mi) SE of Mayagüez, PR · 107 km (66 mi) WSW of San Juan, PR

· 18 km deep · released about 12 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Germán Municipio 1 kmSabana Grande Municipio 9 kmHormigueros Municipio 10 kmMaricao Municipio 12 kmLajas Municipio 14 kmLas Marías Municipio 14 kmYauco Municipio 18 kmCabo Rojo Municipio 20 kmGuánica Municipio 21 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
Magnitude
M 3.9 (md)
Depth
18 km below the surface
Felt
37 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
Nearest
San Germán Municipio, 1 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1310 days ago

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 90 km (56 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.

Likely felt in: San Germán 3 km, intensity III · Mayagüez 16 km, intensity III · Puerto Real 17 km, intensity III · Yauco 20 km, intensity III · Pole Ojea 22 km, intensity III · San Sebastián 26 km, intensity III · Lares 26 km, intensity III · Guayanilla 27 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 12 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 14,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 640× the energy of this one
  3. Magna, Utah 2020 M 5.7 450× the energy of this one
  4. This earthquake M 3.9 about 12 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 25× 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 in our catalogue was M 6.4 on 2020-01-07 — about 5,100 times the energy of this one.

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 18.1068, -67.0268. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Germán Municipio, PR 1 km (1 mi) W earthquakes near San Germán Municipio
Sabana Grande Municipio, PR 9 km (5 mi) ESE earthquakes near Sabana Grande Municipio
Hormigueros Municipio, PR 10 km (6 mi) WNW earthquakes near Hormigueros Municipio
Maricao Municipio, PR 12 km (8 mi) NE earthquakes near Maricao Municipio
Lajas Municipio, PR 14 km (9 mi) S earthquakes near Lajas Municipio
Las Marías Municipio, PR 14 km (9 mi) NNE earthquakes near Las Marías Municipio

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

Aftershocks so far

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

  1. 2.5 7 km SW of Guánica, Puerto Rico
  2. 2.3 3 km SSW of Indios, Puerto Rico
  3. 2.4 7 km SSW of Tallaboa, Puerto Rico
  4. 2.6 6 km SSW of Indios, Puerto Rico
  5. 1.9 7 km SSE of Maria Antonia, Puerto Rico
  6. 2.0 3 km SW of Indios, Puerto Rico
  7. 2.7 2 km SSE of Boquerón, Puerto Rico
  8. 2.8 Puerto Rico region
  9. 2.2 6 km S of Guánica, Puerto Rico
  10. 2.6 0 km S of Maricao, Puerto Rico
  11. 2.6 7 km SSE of Maria Antonia, Puerto Rico
  12. 2.2 2 km ESE of Magas Arriba, Puerto Rico
  13. 2.4 Puerto Rico region
  14. 2.2 2 km SE of Palomas, Puerto Rico
  15. 1.9 Puerto Rico region

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

On USGS

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