QuakeIndex

explosion · reviewed by a seismologist

M 1.5ml

Earthquake near Winlock, WA

No earthquake was likely felt in Winlock in the 24 hours to 3:29 pm PST (23:29 UTC). The last one was M 1.7, 3 km (2 mi) NNE, at 1:54 pm PDT on 2 October 2026, estimated intensity II (weak) in town. Every earthquake near Winlock

No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.5 explosion was recorded 6 km (4 mi) northwest of Winlock, WA, at 1:16 pm PDT on 20 July 2026 (20:16 UTC), less than 1 km deep.

USGS: 6 km NW of Winlock, Washington

58 km (36 mi) S of Olympia, WA · 131 km (81 mi) SSW of Seattle, WA

1:16 pm PDT, Jul 20, 2026 · · -0.4 km deep · released about 5.7 lb of TNT

10 km30 km60 km120 km N Wahkiakum County 41 kmCowlitz County 44 kmThurston County 47 kmLewis County 48 kmPacific County 60 kmColumbia County 65 kmClatsop County 78 kmPierce County 87 kmGrays Harbor County 90 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
1:16 pm PDT on 20 July 2026 ()
Where
6 km (4 mi) northwest of Winlock, WA · earthquakes near Winlock
Magnitude
M 1.5 (ml)
Depth
-0.4 km below the surface
Felt
no reports yet
Nearest
Wahkiakum County, 41 km SW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 98 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 Winlock, 6 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: Napavine, Chehalis, Centralia, Fords Prairie, Castle Rock, Grand Mound.

USGS catalogues this as explosion, not an earthquake.

How big was it?

This earthquake released about 5.7 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 2,600,000× 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 5.7 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 46.5268, -123.0043. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Wahkiakum County, WA 41 km (26 mi) SW earthquakes near Wahkiakum County
Cowlitz County, WA 44 km (28 mi) SE earthquakes near Cowlitz County
Thurston County, WA 47 km (29 mi) NNE earthquakes near Thurston County
Lewis County, WA 48 km (30 mi) E earthquakes near Lewis County
Pacific County, WA 60 km (37 mi) W earthquakes near Pacific County
Columbia County, OR 65 km (41 mi) S earthquakes near Columbia County

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

Aftershocks so far

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

  1. 1.8 3 km SW of Winlock, Washington
  2. 1.4 13 km E of Skamokawa Valley, Washington
  3. 0.7 5 km SSE of Mossyrock, Washington
  4. 1.0 2 km NNE of Mossyrock, Washington
  5. 1.1 10 km NE of Castle Rock, Washington
  6. 1.4 15 km WSW of Tumwater, Washington
  7. 0.7 21 km ESE of Castle Rock, Washington
  8. 1.1 20 km E of Castle Rock, Washington
  9. 1.4 10 km S of Toledo, Washington
  10. 1.5 6 km WSW of Napavine, Washington
  11. 0.3 22 km ESE of Castle Rock, Washington
  12. 0.6 20 km ESE of Castle Rock, Washington
  13. 0.5 20 km ESE of Castle Rock, Washington
  14. 1.1 10 km SSE of Toledo, Washington
  15. 0.1 22 km ESE of Castle Rock, 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.