QuakeIndex

explosion · reviewed by a seismologist

M 1.8ml

Earthquake near Castle Rock, WA

No earthquake was likely felt in Castle Rock in the 24 hours to 1:17 pm PST (21:17 UTC). The last one was M 1.6, 11 km (7 mi) NE, at 4:32 pm PDT on 8 October 2026, estimated intensity II (weak) in town. Every earthquake near Castle Rock

No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.8 explosion was recorded 10 km (6 mi) northeast of Castle Rock, WA, at 11:42 am PST on 13 February 2023 (19:42 UTC), less than 1 km deep.

USGS: 9 km NE of Castle Rock, Washington

89 km (56 mi) N of Portland, OR

11:42 am PST, Feb 13, 2023 · · -0.3 km deep · released about 15 lb of TNT

Every earthquake near Castle Rock Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Cowlitz County 18 kmLewis County 43 kmWahkiakum County 47 kmColumbia County 48 kmThurston County 67 kmClark County 67 kmSkamania County 74 kmClatsop County 77 kmPacific County 79 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
11:42 am PST on 13 February 2023 ()
Where
10 km (6 mi) northeast of Castle Rock, WA · earthquakes near Castle Rock
Magnitude
M 1.8 (ml)
Depth
-0.3 km below the surface
Felt
no reports yet
Nearest
Cowlitz County, 18 km SSE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1369 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 13 km (8 mi) from the epicentre. In Castle Rock, 10 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: West Side Highway, Winlock, Longview Heights, Kelso, West Longview, Longview.

USGS catalogues this as explosion, not an earthquake.

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 5.7 730,000× the energy of this one
  3. Around the size people start to feel M 3.0 65× 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 lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.7 38 km NNE of Amboy, Washington · 50 km ESE of this epicentre
  2. 5.2 37 km NNE of Amboy, Washington · 49 km ESE of this epicentre
  3. 5.2 23 km S of Morton, Washington · 44 km E of this epicentre
  4. 5.1 38 km NNE of Amboy, Washington · 50 km ESE of this epicentre
  5. 5.1 38 km S of Morton, Washington · 50 km ESE 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 46.3327, -122.8095. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Cowlitz County, WA 18 km (11 mi) SSE earthquakes near Cowlitz County
Lewis County, WA 43 km (27 mi) NE earthquakes near Lewis County
Wahkiakum County, WA 47 km (29 mi) W earthquakes near Wahkiakum County
Columbia County, OR 48 km (30 mi) SSW earthquakes near Columbia County
Thurston County, WA 67 km (42 mi) N earthquakes near Thurston County
Clark County, WA 67 km (42 mi) SSE earthquakes near Clark 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. 2.1 20 km SSE of Mossyrock, Washington
  2. 2.0 11 km S of Morton, Washington
  3. 1.7 7 km E of Kalama, Washington
  4. 1.7 24 km N of Amboy, Washington
  5. 1.7 24 km N of Amboy, Washington
  6. 1.5 5 km WSW of Napavine, Washington
  7. 2.2 5 km SW of Napavine, Washington
  8. 1.6 6 km ENE of Mossyrock, Washington
  9. 1.6 11 km NE of Vernonia, Oregon
  10. 1.8 10 km NE of Castle Rock, Washington
  11. 1.6 2 km N of Onalaska, Washington
  12. 2.9 3 km N of Onalaska, Washington
  13. 1.8 4 km NW of Winlock, Washington
  14. 1.5 6 km ESE of East Cathlamet, Washington
  15. 2.0 5 km WSW of Napavine, 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.