Earthquake · reviewed by a seismologist
M 3.4md
Mona Passage
Yes. A magnitude 3.4 earthquake was recorded in Mona Passage, 31 km (20 mi) W of Mayagüez, PR, at 3:41 am AST on 9 April 2023 (07:41 UTC), 7.1 km deep.
31 km (20 mi) W of Mayagüez, PR · 146 km (91 mi) W of San Juan, PR
- When
- Magnitude
- M 3.4 (md)
- Depth
- 7.1 km below the surface
- Felt
- no reports yet
- Nearest
- Rincón Municipio, 23 km ENE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1312 days ago
Earthquake alerts for Stella, PR
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 57 km (35 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: Rincón 23 km, intensity II · Aguada 31 km, intensity II · Puerto Real 31 km, intensity II · Mayagüez 32 km, intensity II · Aguadilla 37 km, intensity II · Pole Ojea 39 km, intensity II · San Germán 45 km, intensity II · Rafael Hernandez 47 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 89,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
- Magna, Utah 2020 M 5.7 2,800× the energy of this one
- This earthquake M 3.4 about 1.9 tons of TNT
- Around the size people start to feel M 3.0 this one released 4× 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 4.5 on 2021-07-18 — about 39 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 18.2275, -67.4377. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Rincón Municipio, PR | 23 km (14 mi) | ENE | earthquakes near Rincón Municipio |
| Aguada Municipio, PR | 31 km (19 mi) | ENE | earthquakes near Aguada Municipio |
| Añasco Municipio, PR | 33 km (21 mi) | ENE | earthquakes near Añasco Municipio |
| Hormigueros Municipio, PR | 35 km (22 mi) | ESE | earthquakes near Hormigueros Municipio |
| Cabo Rojo Municipio, PR | 37 km (23 mi) | SE | earthquakes near Cabo Rojo Municipio |
| Moca Municipio, PR | 41 km (26 mi) | ENE | earthquakes near Moca Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
3 earthquakes have been recorded within 50 km since this one.
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
- 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.