explosion · reviewed by a seismologist
M 1.7ml
Earthquake near Winlock, WA
USGS: 6 km NNW of Winlock, Washington
56 km (35 mi) S of Olympia, WA · 129 km (80 mi) SSW of Seattle, WA
- When
- 6:09 pm PDT on 2 April 2018 ()
- Where
- 6 km (4 mi) NNW of Winlock, WA · earthquakes near Winlock
- Magnitude
- M 1.7 (ml)
- Depth
- -0.3 km below the surface
- Felt
- no reports yet
- Nearest
- Wahkiakum County, 44 km SW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3104 days ago
A magnitude 1.7 earthquake was recorded 6 km (4 mi) NNW of Winlock, WA, at 6:09 pm PDT on 2 April 2018 (01:09 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
Earthquakes near other towns within 30 km: Napavine, Chehalis, Centralia, Fords Prairie, Grand Mound, Castle Rock.
USGS catalogues this as explosion, not an earthquake.
How big was it?
This earthquake released about 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 95× the energy of this one
- This earthquake M 1.7 about 10 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 46.5398, -122.9725. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Wahkiakum County, WA | 44 km (27 mi) | SW | earthquakes near Wahkiakum County |
| Cowlitz County, WA | 44 km (28 mi) | SSE | earthquakes near Cowlitz County |
| Thurston County, WA | 45 km (28 mi) | NNE | earthquakes near Thurston County |
| Lewis County, WA | 46 km (28 mi) | E | earthquakes near Lewis County |
| Pacific County, WA | 62 km (39 mi) | W | earthquakes near Pacific County |
| Columbia County, OR | 67 km (42 mi) | S | earthquakes near Columbia County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
51 earthquakes have been recorded within 50 km since this one.
- 1.7 21 km E of Castle Rock, Washington
- 2.1 29 km E of Castle Rock, Washington
- 1.6 21 km E of Castle Rock, Washington
- 1.9 10 km SSE of Toledo, Washington
- 1.7 20 km SE of Toledo, Washington
- 1.6 12 km NW of West Longview, Washington
- 1.6 11 km SSW of Pe Ell, Washington
- 1.7 3 km NW of West Longview, Washington
- 1.6 4 km W of West Longview, Washington
- 1.8 9 km NW of West Longview, Washington
- 1.8 4 km NW of West Longview, Washington
- 2.9 1 km WSW of Onalaska, Washington
- 2.1 10 km WSW of Chehalis, Washington
- 1.5 3 km ENE of East Cathlamet, Washington
- 3.1 3 km NNE of Onalaska, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.