QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Amboy, WA

No earthquake was likely felt in Amboy in the 24 hours to 3:01 am PST (11:01 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

This page: a magnitude 1.8 earthquake was recorded 25 km (15 mi) north of Amboy, WA, at 3:34 pm PDT on 20 March 2020 (22:34 UTC), 16 km deep.

USGS: 24 km N of Amboy, Washington

68 km (42 mi) NNE of Portland, OR · 56 km (35 mi) N of Vancouver, WA

3:34 pm PDT, Mar 20, 2020 · · 16 km deep · released about 13 lb of TNT

Every earthquake near Amboy Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cowlitz County 17 kmClark County 40 kmSkamania County 42 kmLewis County 50 kmColumbia County 51 kmMultnomah County 65 kmWahkiakum County 75 kmWashington County 80 kmThurston County 93 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
3:34 pm PDT on 20 March 2020 ()
Where
25 km (15 mi) north of Amboy, WA · earthquakes near Amboy
Magnitude
M 1.8 (ml)
Depth
16 km below the surface
Felt
no reports yet
Nearest
Cowlitz County, 17 km WNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 616 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. In Amboy, 25 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.

How big was it?

This earthquake released about 13 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 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. This earthquake M 1.8 about 13 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 · 24 km ENE of this epicentre
  2. 5.2 37 km NNE of Amboy, Washington · 23 km ENE of this epicentre
  3. 5.2 23 km S of Morton, Washington · 30 km NE of this epicentre
  4. 5.1 28 km ENE of Amboy, Washington · 30 km ESE of this epicentre
  5. 5.1 Washington · 26 km ENE 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 46.1323, -122.4742. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cowlitz County, WA 17 km (11 mi) WNW earthquakes near Cowlitz County
Clark County, WA 40 km (25 mi) S earthquakes near Clark County
Skamania County, WA 42 km (26 mi) ESE earthquakes near Skamania County
Lewis County, WA 50 km (31 mi) N earthquakes near Lewis County
Columbia County, OR 51 km (32 mi) WSW earthquakes near Columbia County
Multnomah County, OR 65 km (40 mi) S earthquakes near Multnomah County

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

Aftershocks so far

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

  1. 1.8 2 km N of West Longview, Washington
  2. 1.6 18 km SSE of Mossyrock, Washington
  3. 1.7 3 km SSW of Yacolt, Washington
  4. 1.9 3 km NNW of West Longview, Washington
  5. 1.7 3 km NNE of Deer Island, Oregon
  6. 1.8 1 km ENE of Prescott, Oregon
  7. 1.5 5 km ENE of Lewisville, Washington
  8. 1.6 5 km ESE of Mossyrock, Washington
  9. 1.7 21 km E of Castle Rock, Washington
  10. 1.6 10 km SSE of Toledo, Washington
  11. 1.6 21 km E of Castle Rock, Washington
  12. 1.7 21 km E of Castle Rock, Washington
  13. 2.1 29 km E of Castle Rock, Washington
  14. 1.6 21 km E of Castle Rock, Washington
  15. 1.8 2 km S of Saint Helens, Oregon

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.