QuakeIndex

Earthquake · reviewed by a seismologist

M 4.4mb

134 km N of Brenas, Puerto Rico

Yes. A magnitude 4.4 earthquake was recorded 134 km N of Brenas, Puerto Rico, at 5:45 am AST on 23 October 2016 (09:45 UTC), 48 km deep.

· 48 km deep · released about 60 tons 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 4.4 (mb)
Depth
48 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 3583 days ago

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 121 km (75 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 60 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,800× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 130× the energy of this one
  3. Magna, Utah 2020 M 5.7 89× the energy of this one
  4. This earthquake M 4.4 about 60 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 130× 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. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 5.4 106 km N of Brenas, Puerto Rico · 29 km SSW of this epicentre
  2. 5.0 113 km N of Brenas, Puerto Rico · 21 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 19.6776, -66.2967. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.8 92 km N of San Juan, Puerto Rico
  2. 3.1 91 km N of Brenas, Puerto Rico
  3. 3.0 116 km N of San Juan, Puerto Rico
  4. 3.0 86 km N of Brenas, Puerto Rico
  5. 3.1 162 km N of San Juan, Puerto Rico
  6. 3.1 102 km N of San Juan, Puerto Rico
  7. 3.2 113 km N of Brenas, Puerto Rico
  8. 2.6 104 km N of Brenas, Puerto Rico
  9. 3.3 105 km N of Brenas, Puerto Rico
  10. 3.8 131 km N of Brenas, Puerto Rico
  11. 3.3 114 km N of San Juan, Puerto Rico
  12. 3.4 128 km N of San Juan, Puerto Rico
  13. 3.2 98 km N of San Juan, Puerto Rico
  14. 3.3 Puerto Rico region
  15. 3.4 93 km N of San Juan, 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.