QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6ml

26 km N of Mackay, Idaho

Yes. A magnitude 1.6 earthquake was recorded 26 km N of Mackay, Idaho, at 1:31 pm MDT on 18 May 2025 (19:31 UTC), 5.0 km deep.

· 5.0 km deep · released about 9 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Custer County 54 kmButte County 62 kmLemhi County 89 kmBlaine County 89 kmClark County 100 kmJefferson County 109 kmCamas County 119 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
Idaho today
every earthquake in Idaho in the last 24 hours
Magnitude
M 1.6 (ml)
Depth
5.0 km below the surface
Felt
no reports yet
Nearest
Custer County, 54 km WNW
Nearest mapped fault
Lost River fault, 16 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 541 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 11 km (7 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 9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
  3. Around the size people start to feel M 3.0 110× the energy of this one
  4. This earthquake M 1.6 about 9 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 5 earthquakes of M5 or more within 50 km:

  1. 6.9 The 1983 Borah Peak Earthquake, Idaho · 24 km WSW of this epicentre
  2. 5.6 18 km ESE of Challis, Idaho · 48 km NW of this epicentre
  3. 5.5 22 km E of Clayton, Idaho · 44 km WNW of this epicentre
  4. 5.4 29 km NW of Mackay, Idaho · 27 km WSW of this epicentre
  5. 5.4 23 km E of Clayton, Idaho · 42 km WNW 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 44.1545, -113.5900. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Custer County, ID 54 km (34 mi) WNW earthquakes near Custer County
Butte County, ID 62 km (38 mi) SSE earthquakes near Butte County
Lemhi County, ID 89 km (55 mi) NNW earthquakes near Lemhi County
Blaine County, ID 89 km (56 mi) SSW earthquakes near Blaine County
Clark County, ID 100 km (62 mi) E earthquakes near Clark County
Jefferson County, ID 109 km (68 mi) ESE earthquakes near Jefferson County

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

Aftershocks so far

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

  1. 1.7 25 km SSE of Challis, Idaho
  2. 2.3 26 km E of Clayton, Idaho
  3. 2.4 27 km E of Clayton, Idaho
  4. 2.3 28 km E of Clayton, Idaho
  5. 1.8 27 km E of Clayton, Idaho
  6. 2.3 27 km E of Clayton, Idaho
  7. 2.2 26 km E of Clayton, Idaho
  8. 2.4 26 km E of Clayton, Idaho
  9. 2.4 26 km E of Clayton, Idaho
  10. 2.1 26 km E of Clayton, Idaho
  11. 2.0 26 km E of Clayton, Idaho
  12. 3.2 25 km E of Clayton, Idaho
  13. 4.3 24 km E of Clayton, Idaho
  14. 1.7 15 km SE of Challis, Idaho

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.