QuakeIndex

other event · reviewed by a seismologist

M 3.3mb_lg

8 km SE of Knoxville, Iowa

· 0.0 km deep · released about 1.3 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Marion County 9 kmMonroe County 30 kmLucas County 35 kmMahaska County 35 kmWarren County 44 kmJasper County 47 kmWapello County 59 kmAppanoose County 59 kmWayne County 63 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 3.3 (mb_lg)
Depth
0.0 km below the surface
Felt
no reports yet
Nearest
Marion County, 9 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 52 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

USGS catalogues this as other event, not an earthquake.

How big was it?

This earthquake released about 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 130,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
  3. Magna, Utah 2020 M 5.7 4,000× the energy of this one
  4. This earthquake M 3.3 about 1.3 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 2.8× 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.

Where

Epicentre 41.2624, -93.0489. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Marion County, IA 9 km (5 mi) SSE of here earthquakes near Marion County
Monroe County, IA 30 km (19 mi) NNW of here earthquakes near Monroe County
Lucas County, IA 35 km (22 mi) NE of here earthquakes near Lucas County
Mahaska County, IA 35 km (22 mi) WSW of here earthquakes near Mahaska County
Warren County, IA 44 km (27 mi) E of here earthquakes near Warren County
Jasper County, IA 47 km (29 mi) S of here earthquakes near Jasper County

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

Aftershocks so far

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

  1. 2.5 10 km WNW of Marysville, Iowa
  2. 3.0 5 km S of Knoxville, Iowa

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.