QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Humacao, PR

No earthquake was likely felt in Humacao in the 24 hours to 4:43 pm AST (20:43 UTC). The last one was M 4.1, 56 km (35 mi) ESE, at 5:44 am AST on 28 October 2026, estimated intensity II (weak) in town; 5 felt reports to USGS. Every earthquake near Humacao

This page: a magnitude 1.8 earthquake was recorded 47 km (29 mi) south-southeast of Humacao, PR, at 4:37 am AST on 1 October 2019 (08:37 UTC), 4.0 km deep.

USGS: 33 km SSE of Emajagua, Puerto Rico

82 km (51 mi) SSE of San Juan, PR

4:37 am AST, Oct 1, 2019 · · 4.0 km deep · released about 14 lb of TNT

Every earthquake near Humacao Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Maunabo Municipio 34 kmYabucoa Municipio 38 kmPatillas Municipio 40 kmArroyo Municipio 42 kmHumacao Municipio 44 kmGuayama Municipio 51 kmLas Piedras Municipio 52 kmSan Lorenzo Municipio 52 kmNaguabo Municipio 52 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
4:37 am AST on 1 October 2019 ()
Where
47 km (29 mi) south-southeast of Humacao, PR · earthquakes near Humacao
Magnitude
M 1.8 (md)
Depth
4.0 km below the surface
Felt
no reports yet
Nearest
Maunabo Municipio, 34 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2598 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 13 km (8 mi) from the epicentre. In Humacao, 47 km away, the estimate is intensity I (not felt). 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 14 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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 18,000 times the energy of this one.

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

  1. 5.3 68 km SSE of Emajagua, Puerto Rico · 38 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 17.7395, -65.7276. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Maunabo Municipio, PR 34 km (21 mi) NNW earthquakes near Maunabo Municipio
Yabucoa Municipio, PR 38 km (24 mi) NNW earthquakes near Yabucoa Municipio
Patillas Municipio, PR 40 km (25 mi) NW earthquakes near Patillas Municipio
Arroyo Municipio, PR 42 km (26 mi) NW earthquakes near Arroyo Municipio
Humacao Municipio, PR 44 km (28 mi) N earthquakes near Humacao Municipio
Guayama Municipio, PR 51 km (31 mi) WNW earthquakes near Guayama Municipio

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

Aftershocks so far

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

  1. 3.2 21 km S of Esperanza, Puerto Rico
  2. 3.5 10 km SSE of Esperanza, Puerto Rico
  3. 3.4 26 km SSW of Esperanza, Puerto Rico
  4. 2.9 1 km SW of Arroyo, Puerto Rico
  5. 2.8 19 km SSE of Esperanza, Puerto Rico
  6. 1.7 9 km SE of Emajagua, Puerto Rico
  7. 2.3 2 km W of Humacao, Puerto Rico
  8. 2.9 62 km SSE of Emajagua, Puerto Rico
  9. 2.7 22 km SE of Emajagua, Puerto Rico
  10. 2.7 18 km SSW of Esperanza, Puerto Rico
  11. 2.1 13 km WSW of Esperanza, Puerto Rico
  12. 3.0 29 km S of Esperanza, Puerto Rico
  13. 2.6 23 km SE of Emajagua, Puerto Rico
  14. 2.8 7 km SW of Esperanza, Puerto Rico
  15. 2.3 5 km SSE of El Negro, 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.