Earthquake · reviewed by a seismologist
M 4.2md
91 km NNW of San Antonio, Puerto Rico
Yes. A magnitude 4.2 earthquake was recorded 91 km NNW of San Antonio, Puerto Rico, at 10:54 am AST on 27 August 2017 (14:54 UTC), 42 km deep.
- When
- Magnitude
- M 4.2 (md)
- Depth
- 42 km below the surface
- Felt
- no reports yet
- Nearest
- Aguadilla Municipio, 92 km S
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3270 days ago
Earthquake alerts for Isabela, 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 light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
At this magnitude and depth, people at rest would likely notice it out to about 103 km (64 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 28 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 6,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 270× the energy of this one
- Magna, Utah 2020 M 5.7 190× the energy of this one
- This earthquake M 4.2 about 28 tons of TNT
- Around the size people start to feel M 3.0 this one released 59× 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.1 on 2017-07-17.
Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:
- 7.7 45 km N of San Antonio, Puerto Rico · 47 km SSE of this epicentre
- 6.8 94 km NE of Punta Cana, Dominican Republic · 48 km WSW of this epicentre
- 6.0 93 km NNW of San Antonio, Puerto Rico · 2 km NNE of this epicentre
- 6.0 81 km N of Isabela, Puerto Rico · 39 km ESE of this epicentre
- 6.0 67 km NNW of San Antonio, Puerto Rico · 25 km S of this epicentre
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 19.2990, -67.2920. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Aguadilla Municipio, PR | 92 km (57 mi) | S | earthquakes near Aguadilla Municipio |
| Isabela Municipio, PR | 95 km (59 mi) | SSE | earthquakes near Isabela Municipio |
| Quebradillas Municipio, PR | 100 km (62 mi) | SSE | earthquakes near Quebradillas Municipio |
| Aguada Municipio, PR | 103 km (64 mi) | S | earthquakes near Aguada Municipio |
| Moca Municipio, PR | 105 km (65 mi) | SSE | earthquakes near Moca Municipio |
| Camuy Municipio, PR | 105 km (65 mi) | SSE | earthquakes near Camuy Municipio |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
46 earthquakes have been recorded within 50 km since this one.
- 3.0 67 km NNE of Isabela, Puerto Rico
- 3.0 68 km N of Isabela, Puerto Rico
- 3.0 66 km NNE of Isabela, Puerto Rico
- 3.1 84 km N of Isabela, Puerto Rico
- 3.0 65 km N of Isabela, Puerto Rico
- 3.1 53 km N of Isabela, Puerto Rico
- 2.9 98 km NNW of San Antonio, Puerto Rico
- 2.9 55 km NNW of San Antonio, Puerto Rico
- 2.8 50 km N of Isabela, Puerto Rico
- 2.9 48 km NNW of San Antonio, Puerto Rico
- 2.9 90 km N of Isabela, Puerto Rico
- 2.8 Mona Passage
- 3.2 42 km NNW of San Antonio, Puerto Rico
- 2.6 50 km NW of San Antonio, Puerto Rico
- 3.3 59 km NNW of San Antonio, Puerto Rico
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.