QuakeIndex

Earthquake · reviewed by a seismologist

M 5.2mww

189 km SSE of Unalaska, Alaska

Yes. A magnitude 5.2 earthquake was recorded 189 km SSE of Unalaska, Alaska at 18:11 UTC on 2019-08-03, 23 km deep. 1 person has reported feeling it to USGS.

· 23 km deep · released about 950 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 5.2 (mww)
Depth
23 km below the surface
Felt
1 report · strongest reported intensity II
Nearest mapped fault
Alaska-Aleutian subduction zone, 11 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 326 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 217 km (135 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 950 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.2 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 180× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 7.9× the energy of this one
  3. Magna, Utah 2020 M 5.7 5.6× the energy of this one
  4. This earthquake M 5.2 about 950 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2,000× 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 5 earthquakes of M5 or more within 50 km:

  1. 7.0 203 km SSE of Unalaska, Alaska · 16 km SE of this epicentre
  2. 6.5 183 km S of Unalaska, Alaska · 45 km W of this epicentre
  3. 6.0 221 km S of Unalaska, Alaska · 41 km SSW of this epicentre
  4. 5.5 198 km SSE of Unalaska, Alaska · 34 km E of this epicentre
  5. 5.3 193 km ESE of Nikolski, Alaska · 48 km WSW 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 52.2481, -165.6894. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 185 km SSE of Unalaska, Alaska
  2. 2.9 south of the Aleutian Islands
  3. 2.9 south of the Aleutian Islands
  4. 2.1 198 km SSE of Unalaska, Alaska
  5. 2.6 south of the Aleutian Islands
  6. 1.7 179 km SSE of Unalaska, Alaska
  7. 2.4 195 km SSE of Unalaska, Alaska
  8. 2.3 208 km S of Unalaska, Alaska
  9. 3.1 196 km SSE of Unalaska, Alaska
  10. 2.5 179 km SSE of Unalaska, Alaska
  11. 2.8 192 km SSE of Unalaska, Alaska
  12. 2.9 197 km SSE of Unalaska, Alaska
  13. 2.3 194 km SSE of Unalaska, Alaska
  14. 3.0 199 km S of Unalaska, Alaska
  15. 2.4 189 km S of Unalaska, Alaska

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.