QuakeIndex

explosion · reviewed by a seismologist

M 1.5ml

Earthquake near Amboy, WA

No earthquake was likely felt in Amboy in the 24 hours to 5:28 am PST (13:28 UTC). The last one was M 1.6, 11 km (7 mi) S, at 4:25 pm PDT on 19 October 2026, estimated intensity II (weak) in town. Every earthquake near Amboy

No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.5 explosion was recorded 23 km (14 mi) north-northeast of Amboy, WA, at 1:40 pm PST on 14 December 2018 (21:40 UTC), less than 1 km deep.

USGS: 22 km NNE of Amboy, Washington

67 km (42 mi) NNE of Portland, OR · 55 km (34 mi) NNE of Vancouver, WA

1:40 pm PST, Dec 14, 2018 · · -1.2 km deep · released about 5.6 lb of TNT

10 km30 km60 km120 km N Cowlitz County 29 kmSkamania County 30 kmClark County 38 kmLewis County 54 kmColumbia County 61 kmMultnomah County 61 kmHood River County 83 kmWashington County 85 kmWahkiakum County 87 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
1:40 pm PST on 14 December 2018 ()
Where
23 km (14 mi) north-northeast of Amboy, WA · earthquakes near Amboy
Magnitude
M 1.5 (ml)
Depth
-1.2 km below the surface
Felt
no reports yet
Nearest
Cowlitz County, 29 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2886 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 10 km (6 mi) from the epicentre. In Amboy, 23 km away, the estimate is intensity II (weak). 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.

Earthquakes near other towns within 30 km: Yacolt.

USGS catalogues this as explosion, not an earthquake.

How big was it?

This earthquake released about 5.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.6 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 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.7 38 km NNE of Amboy, Washington · 16 km NE of this epicentre
  2. 5.2 37 km NNE of Amboy, Washington · 16 km NE of this epicentre
  3. 5.2 23 km S of Morton, Washington · 29 km NNE of this epicentre
  4. 5.1 28 km ENE of Amboy, Washington · 18 km ESE of this epicentre
  5. 5.1 Washington · 19 km NE 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 46.0973, -122.3302. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cowlitz County, WA 29 km (18 mi) WNW earthquakes near Cowlitz County
Skamania County, WA 30 km (19 mi) ESE earthquakes near Skamania County
Clark County, WA 38 km (24 mi) SSW earthquakes near Clark County
Lewis County, WA 54 km (33 mi) N earthquakes near Lewis County
Columbia County, OR 61 km (38 mi) WSW earthquakes near Columbia County
Multnomah County, OR 61 km (38 mi) S earthquakes near Multnomah 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 4 km NE of Amboy, Washington
  2. 1.5 2 km W of Yacolt, Washington
  3. 2.5 16 km NE of Kalama, Washington
  4. 1.7 1 km NE of Lewisville, Washington
  5. 1.8 2 km NE of Deer Island, Oregon
  6. 1.6 3 km WSW of Yacolt, Washington
  7. 1.6 14 km SSW of Morton, Washington
  8. 1.6 21 km SSE of Mossyrock, Washington
  9. 1.5 3 km SW of Yacolt, Washington
  10. 1.8 9 km S of Toledo, Washington
  11. 1.7 6 km ENE of Prescott, Oregon
  12. 1.6 9 km SSE of Toledo, Washington
  13. 1.6 12 km SSE of Toledo, Washington
  14. 1.7 13 km ESE of Yacolt, Washington
  15. 1.8 20 km NNW of Carson, Washington

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.