QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Alamosa, CO

USGS: 23 km N of Blanca, Colorado

10:22 am MDT, Apr 27, 2019 · · 5.0 km deep · released about 15 lb of TNT

Every earthquake near Alamosa Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alamosa County 28 kmCostilla County 42 kmHuerfano County 47 kmCuster County 51 kmConejos County 78 kmSaguache County 78 kmRio Grande County 87 kmFremont County 90 kmPueblo County 105 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
10:22 am MDT on 27 April 2019 ()
Where
39 km (24 mi) ENE of Alamosa, CO · earthquakes near Alamosa
Magnitude
M 1.8 (ml)
Depth
5.0 km below the surface
Felt
no reports yet
Nearest
Alamosa County, 28 km WSW
Nearest mapped fault
Northern Sangre de Cristo fault, 5 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 2638 days ago

A magnitude 1.8 earthquake was recorded 39 km (24 mi) ENE of Alamosa, CO, at 10:22 am MDT on 27 April 2019 (16:22 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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 since 1900 lists no earthquake of M5 or more within 50 km.

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 37.6483, -105.4902. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alamosa County, CO 28 km (17 mi) WSW earthquakes near Alamosa County
Costilla County, CO 42 km (26 mi) S earthquakes near Costilla County
Huerfano County, CO 47 km (29 mi) E earthquakes near Huerfano County
Custer County, CO 51 km (32 mi) NNE earthquakes near Custer County
Conejos County, CO 78 km (48 mi) SW earthquakes near Conejos County
Saguache County, CO 78 km (48 mi) WNW earthquakes near Saguache County

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. 1.6 6 km W of La Veta, Colorado
  2. 1.6 5 km WSW of La Veta, Colorado
  3. 1.6 3 km WNW of La Veta, Colorado
  4. 1.8 3 km W of La Veta, Colorado
  5. 1.5 3 km WNW of La Veta, Colorado
  6. 1.5 5 km NNW of La Veta, Colorado
  7. 2.1 3 km WNW of La Veta, Colorado
  8. 1.5 3 km W of La Veta, Colorado
  9. 2.4 2 km WNW of La Veta, Colorado
  10. 1.7 4 km W of La Veta, Colorado
  11. 1.5 20 km N of Blanca, Colorado
  12. 1.7 Colorado
  13. 1.5 26 km N of Fort Garland, Colorado
  14. 1.5 22 km N of Blanca, Colorado
  15. 2.1 23 km N of Blanca, Colorado

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.