QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

78 km SE of Igiugig, Alaska

Yes. A magnitude 2.1 earthquake was recorded 78 km SE of Igiugig, Alaska at 12:24 UTC on 2018-09-05, 145 km deep.

· 145 km deep · released about 43 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake and Peninsula Borough 104 kmBristol Bay Borough 108 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 2.1 (ml)
Depth
145 km below the surface
Felt
no reports yet
Nearest
Lake and Peninsula Borough, 104 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1185 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. This earthquake M 2.1 about 43 lb of TNT

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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 52 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.0 Event 36 Novarupta-Mount Katmai area, Alaska Peninsula · 50 km S of this epicentre
  2. 6.8 Event 37 Novarupta-Mount Katmai area, Alaska Peninsula · 50 km S of this epicentre
  3. 6.6 Event 39 Novarupta-Mount Katmai area, Alaska Peninsula · 50 km S of this epicentre
  4. 6.6 74 km S of Kokhanok, Alaska · 24 km E of this epicentre
  5. 6.5 Event 21 Novarupta-Mount Katmai area, Alaska Peninsula · 50 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 58.7448, -155.1151. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake and Peninsula Borough, AK 104 km (64 mi) SW earthquakes near Lake and Peninsula Borough
Bristol Bay Borough, AK 108 km (67 mi) W earthquakes near Bristol Bay Borough
Kodiak Island Borough, AK 135 km (84 mi) SSE earthquakes near Kodiak Island 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. 2.3 84 km SSE of Igiugig, Alaska
  2. 1.6 101 km NNW of Karluk, Alaska
  3. 1.9 59 km S of Kokhanok, Alaska
  4. 3.4 76 km S of Kokhanok, Alaska
  5. 1.6 94 km ESE of King Salmon, Alaska
  6. 1.9 82 km E of King Salmon, Alaska
  7. 1.8 91 km NNW of Karluk, Alaska
  8. 1.7 88 km S of Kokhanok, Alaska
  9. 2.1 70 km S of Kokhanok, Alaska
  10. 1.9 84 km E of King Salmon, Alaska
  11. 1.9 83 km SSW of Kokhanok, Alaska
  12. 1.7 98 km N of Karluk, Alaska
  13. 1.5 97 km E of King Salmon, Alaska
  14. 2.0 96 km NNW of Karluk, Alaska
  15. 2.8 65 km ESE of King Salmon, 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.