explosion · reviewed by a seismologist
M 1.7ml
Earthquake near Longview, WA
USGS: 8 km S of Toledo, Washington
93 km (58 mi) N of Portland, OR
- When
- 4:44 pm PDT on 18 September 2018 ()
- Where
- 27 km (17 mi) NNE of Longview, WA · earthquakes near Longview
- Magnitude
- M 1.7 (ml)
- Depth
- -0.8 km below the surface
- Felt
- no reports yet
- Nearest
- Cowlitz County, 22 km SSE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2936 days ago
A magnitude 1.7 earthquake was recorded 27 km (17 mi) NNE of Longview, WA, at 4:44 pm PDT on 18 September 2018 (23:44 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
Earthquakes near other towns within 30 km: Castle Rock, Winlock, West Side Highway, Longview Heights, Napavine, Kelso.
USGS catalogues this as explosion, not an earthquake.
How big was it?
This earthquake released about 11 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 1,400,000× the energy of this one
- Magna, Utah 2020 M 5.7 970,000× the energy of this one
- Around the size people start to feel M 3.0 86× the energy of this one
- This earthquake M 1.7 about 11 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 one earthquake of M5 or more within 50 km:
- 5.2 23 km S of Morton, Washington · 46 km E 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 46.3657, -122.8305. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Cowlitz County, WA | 22 km (14 mi) | SSE | earthquakes near Cowlitz County |
| Lewis County, WA | 42 km (26 mi) | NE | earthquakes near Lewis County |
| Wahkiakum County, WA | 46 km (29 mi) | W | earthquakes near Wahkiakum County |
| Columbia County, OR | 51 km (32 mi) | SSW | earthquakes near Columbia County |
| Thurston County, WA | 63 km (39 mi) | N | earthquakes near Thurston County |
| Clark County, WA | 71 km (44 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.
- 3.1 3 km NNE of Onalaska, Washington
- 1.6 14 km SSW of Morton, Washington
- 1.6 21 km SSE of Mossyrock, Washington
- 1.8 9 km S of Toledo, Washington
- 1.7 6 km ENE of Prescott, Oregon
- 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
- 1.6 6 km SSW of Morton, Washington
- 1.6 16 km ENE of Kalama, Washington
- 1.5 6 km SE of Onalaska, Washington
- 1.8 0 km SW of Kalama, Washington
- 1.8 23 km SSE 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.