explosion · reviewed by a seismologist
M 1.7ml
Earthquake near Winlock, WA
USGS: 10 km NW of Winlock, Washington
55 km (34 mi) SSW of Olympia, WA · 130 km (81 mi) SSW of Seattle, WA
- When
- 2:07 pm PDT on 20 September 2016 ()
- Where
- 10 km (6 mi) NW of Winlock, WA · earthquakes near Winlock
- Magnitude
- M 1.7 (ml)
- Depth
- -0.2 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 558 days ago
A magnitude 1.7 earthquake was recorded 10 km (6 mi) NW of Winlock, WA, at 2:07 pm PDT on 20 September 2016 (21:07 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.
USGS catalogues this as explosion, not an earthquake.
How big was it?
This earthquake released about 9.3 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 1,600,000× 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 3.0 100× the energy of this one
- This earthquake M 1.7 about 9.3 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 46.5522, -123.0407. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Wahkiakum County, WA | 41 km (26 mi) | SW | earthquakes near Wahkiakum County |
| Thurston County, WA | 46 km (28 mi) | NNE | earthquakes near Thurston County |
| Cowlitz County, WA | 48 km (30 mi) | SE | earthquakes near Cowlitz County |
| Lewis County, WA | 51 km (32 mi) | E | earthquakes near Lewis County |
| Pacific County, WA | 57 km (35 mi) | W | earthquakes near Pacific County |
| Columbia County, OR | 68 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
55 earthquakes have been recorded within 50 km since this one.
- 3.1 3 km NNE of Onalaska, Washington
- 1.8 9 km S of Toledo, Washington
- 1.6 9 km SSE of Toledo, Washington
- 1.6 12 km SSE of Toledo, Washington
- 1.9 8 km NW of West Longview, Washington
- 1.6 4 km W of Mossyrock, Washington
- 1.7 3 km NW of West Longview, Washington
- 1.5 6 km SE of Onalaska, Washington
- 1.9 6 km NNW of West Longview, Washington
- 1.8 2 km SSW of Cathlamet, Washington
- 1.6 15 km SW of Ryderwood, Washington
- 1.7 3 km WSW of Cathlamet, Washington
- 1.8 18 km ESE of Castle Rock, Washington
- 1.8 8 km NNW of West Longview, Washington
- 1.5 25 km S of Mossyrock, 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.