QuakeIndex

Earthquake · reviewed by a seismologist

M 3.1md

138 km N of Charlotte Amalie, U.S. Virgin Islands

Yes. A magnitude 3.1 earthquake was recorded 138 km N of Charlotte Amalie, U.S. Virgin Islands, at 10:38 am AST on 1 August 2019 (14:38 UTC), 140 km deep.

· 140 km deep · released about 1,400 lb of TNT

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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 3.1 (md)
Depth
140 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2580 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 it was probably too small to be felt, even directly above it. 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 1,400 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 240,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 7,700× the energy of this one
  4. This earthquake M 3.1 about 1,400 lb of TNT
  5. Around the size people start to feel M 3.0 this one released 1.5× 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 since 2016 was M 4.9 on 2018-11-14 — about 480 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 112 km N of Charlotte Amalie, U.S. Virgin Islands · 30 km SE of this epicentre
  2. 5.6 112 km N of Charlotte Amalie, U.S. Virgin Islands · 33 km SE of this epicentre
  3. 5.1 107 km N of Charlotte Amalie, U.S. Virgin Islands · 33 km SSE of this epicentre
  4. 5.1 122 km NNE of Vieques, Puerto Rico · 30 km SW of this epicentre
  5. 5.0 122 km N of Charlotte Amalie, U.S. Virgin Islands · 23 km SE 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 19.5791, -65.0926. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.3 119 km N of Charlotte Amalie, U.S. Virgin Islands
  2. 3.2 124 km N of Charlotte Amalie, U.S. Virgin Islands
  3. 2.7 Puerto Rico region
  4. 3.0 120 km NNE of Vieques, Puerto Rico
  5. 3.5 146 km N of Charlotte Amalie, U.S. Virgin Islands
  6. 3.4 111 km N of Charlotte Amalie, U.S. Virgin Islands
  7. 3.6 136 km N of Cruz Bay, U.S. Virgin Islands
  8. 2.6 123 km N of Charlotte Amalie, U.S. Virgin Islands
  9. 3.0 122 km N of Charlotte Amalie, U.S. Virgin Islands
  10. 3.2 126 km N of Cruz Bay, U.S. Virgin Islands
  11. 3.2 145 km N of Cruz Bay, U.S. Virgin Islands
  12. 2.9 112 km N of Cruz Bay, U.S. Virgin Islands
  13. 3.3 135 km N of Charlotte Amalie, U.S. Virgin Islands
  14. 2.9 126 km N of Cruz Bay, U.S. Virgin Islands
  15. 3.4 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.