QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1md

Earthquake near Arroyo, PR

No earthquake was likely felt in Arroyo in the 24 hours to 12:56 pm AST (16:56 UTC). The last one was M 3.3, 39 km (24 mi) WSW, at 8:40 am AST on 1 November 2026, estimated intensity II (weak) in town. Every earthquake near Arroyo

This page: a magnitude 2.1 earthquake was recorded 5 km (3 mi) east-southeast of Arroyo, PR, at 11:08 am AST on 12 May 2018 (15:08 UTC), 14 km deep.

USGS: 4 km ESE of Arroyo, Puerto Rico

51 km (32 mi) S of San Juan, PR · 32 km (20 mi) S of Caguas, PR

11:08 am AST, May 12, 2018 · · 14 km deep · released about 38 lb of TNT

Every earthquake near Arroyo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Arroyo Municipio 4 kmPatillas Municipio 7 kmGuayama Municipio 13 kmMaunabo Municipio 15 kmYabucoa Municipio 22 kmCayey Municipio 22 kmSan Lorenzo Municipio 23 kmSalinas Municipio 25 kmCidra Municipio 30 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
11:08 am AST on 12 May 2018 ()
Where
5 km (3 mi) east-southeast of Arroyo, PR · earthquakes near Arroyo
Magnitude
M 2.1 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Arroyo Municipio, 4 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3105 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 9 km (6 mi) from the epicentre. In Arroyo, 5 km away, the estimate is intensity II (weak). 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.

Earthquakes near other towns within 30 km: Palmas, Lamboglia, Buena Vista, Patillas, Corazón, Yaurel.

How big was it?

This earthquake released about 38 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 390,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 280,000× the energy of this one
  3. Around the size people start to feel M 3.0 25× the energy of this one
  4. This earthquake M 2.1 about 38 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 4.6 on 2016-12-05 — about 6,200 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.1 3 km W of Aguas Buenas, Puerto Rico · 37 km NNW 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 17.9431, -66.0235. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Arroyo Municipio, PR 4 km (2 mi) NNW earthquakes near Arroyo Municipio
Patillas Municipio, PR 7 km (5 mi) NNE earthquakes near Patillas Municipio
Guayama Municipio, PR 13 km (8 mi) WNW earthquakes near Guayama Municipio
Maunabo Municipio, PR 15 km (9 mi) ENE earthquakes near Maunabo Municipio
Yabucoa Municipio, PR 22 km (13 mi) NE earthquakes near Yabucoa Municipio
Cayey Municipio, PR 22 km (14 mi) NW earthquakes near Cayey Municipio

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

Aftershocks so far

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

  1. 2.0 1 km N of Bayamon, Puerto Rico
  2. 1.7 8 km NNE of Emajagua, Puerto Rico
  3. 2.7 8 km S of Palo Seco, Puerto Rico
  4. 1.7 10 km S of Emajagua, Puerto Rico
  5. 3.0 11 km S of Emajagua, Puerto Rico
  6. 2.4 9 km SSE of Punta Santiago, Puerto Rico
  7. 1.6 0 km W of Jobos, Puerto Rico
  8. 2.3 9 km S of Jauca, Puerto Rico
  9. 2.1 12 km S of Jobos, Puerto Rico
  10. 1.9 1 km NE of Jauca, Puerto Rico
  11. 2.2 2 km NE of Jauca, Puerto Rico
  12. 1.7 0 km NNE of Las Ollas, Puerto Rico
  13. 2.0 3 km SW of Guaynabo, Puerto Rico
  14. 2.4 2 km SW of Sumidero, Puerto Rico
  15. 2.1 7 km SSW of Lamboglia, 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

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