QuakeIndex

Earthquake · reviewed by a seismologist

M 5.1mww

48 km NW of Ninilchik, Alaska

Yes. A magnitude 5.1 earthquake was recorded 48 km NW of Ninilchik, Alaska, at 8:18 pm AKST on 20 January 2022 (05:18 UTC), 115 km deep. 911 people have reported feeling it to USGS.

· 115 km deep · released about 670 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kenai Peninsula Borough 6 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
Magnitude
M 5.1 (mww)
Depth
115 km below the surface
Felt
911 reports · strongest reported intensity V
Measured shaking
intensity IV (ShakeMap)
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Kenai Peninsula Borough, 6 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1042 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 170 km (106 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 670 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.1 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 250× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 11× the energy of this one
  3. Magna, Utah 2020 M 5.7 7.9× the energy of this one
  4. This earthquake M 5.1 about 670 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 1,400× 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 4.9 on 2017-08-11.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 75 km WNW of Ninilchik, Alaska · 33 km W of this epicentre
  2. 6.2 16 km WNW of Happy Valley, Alaska · 40 km SSE of this epicentre
  3. 6.2 70 km E of Port Alsworth, Alaska · 43 km WSW of this epicentre
  4. 6.1 73 km WNW of Ninilchik, Alaska · 26 km WNW of this epicentre
  5. 5.9 66 km ENE of Pedro Bay, Alaska · 49 km SW 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 60.3163, -152.3603. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kenai Peninsula Borough, AK 6 km (4 mi) NNE earthquakes near Kenai Peninsula Borough

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

Aftershocks so far

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

  1. 2.6 38 km W of Salamatof, Alaska
  2. 1.6 45 km NW of Ninilchik, Alaska
  3. 1.7 59 km WNW of Anchor Point, Alaska
  4. 1.5 39 km NW of Ninilchik, Alaska
  5. 1.5 41 km NW of Ninilchik, Alaska
  6. 1.5 52 km WNW of Ninilchik, Alaska
  7. 2.3 22 km NNW of Ninilchik, Alaska
  8. 1.6 68 km W of Salamatof, Alaska
  9. 2.1 67 km W of Salamatof, Alaska
  10. 1.7 58 km WNW of Ninilchik, Alaska
  11. 2.5 70 km WNW of Ninilchik, Alaska
  12. 1.7 31 km WNW of Cohoe, Alaska
  13. 1.9 35 km WNW of Anchor Point, Alaska
  14. 2.2 61 km W of Happy Valley, Alaska
  15. 2.3 56 km NW of Ninilchik, 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.