QuakeIndex

Earthquake · reviewed by a seismologist

M 4.9mb

112 km SSW of Sand Point, Alaska

Yes. A magnitude 4.9 earthquake was recorded 112 km SSW of Sand Point, Alaska, at 7:29 pm AKDT on 13 April 2018 (03:29 UTC), 34 km deep.

· 34 km deep · released about 340 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 4.9 (mb)
Depth
34 km below the surface
Felt
no reports yet
Nearest
Aleutians East Borough, 124 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1187 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 178 km (111 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 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 500× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 22× the energy of this one
  3. Magna, Utah 2020 M 5.7 16× the energy of this one
  4. This earthquake M 4.9 about 340 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 710× 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. The previous largest was M 4.6 on 2016-11-23.

Before 2016, the USGS record lists 28 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 90 km SE of King Cove, Alaska · 34 km NW of this epicentre
  2. 6.4 101 km SSW of Sand Point, Alaska · 21 km NW of this epicentre
  3. 6.4 109 km SSE of King Cove, Alaska · 39 km WSW of this epicentre
  4. 6.4 85 km ESE of King Cove, Alaska · 41 km NNW of this epicentre
  5. 6.2 141 km SSE of King Cove, Alaska · 43 km SSW 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 54.3449, -160.8569. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Aleutians East Borough, AK 124 km (77 mi) NW earthquakes near Aleutians East Borough

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

Aftershocks so far

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

  1. 2.3 119 km SSW of Sand Point, Alaska
  2. 3.8 99 km S of Sand Point, Alaska
  3. 3.1 98 km S of Sand Point, Alaska
  4. 3.1 102 km SSW of Sand Point, Alaska
  5. 2.1 Alaska Peninsula
  6. 1.9 103 km SSW of Sand Point, Alaska
  7. 2.1 91 km SSW of Sand Point, Alaska
  8. 1.8 99 km S of Sand Point, Alaska
  9. 3.8 99 km SSW of Sand Point, Alaska
  10. 3.9 94 km S of Sand Point, Alaska
  11. 5.3 102 km S of Sand Point, Alaska
  12. 2.1 109 km SSW of Sand Point, Alaska
  13. 3.5 101 km SSW of Sand Point, Alaska
  14. 2.1 114 km S of Sand Point, Alaska
  15. 2.4 101 km S of Sand Point, 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.