explosion · reviewed by a seismologist
M 1.6ml
Earthquake near Longview, WA
No earthquake was likely felt in Longview in the 24 hours to 11:25 am PST (19:25 UTC). The last one was M 3.0, 29 km (18 mi) SSE, at 7:25 am PDT on 22 October 2026, estimated intensity II (weak) in town; 113 felt reports to USGS. Every earthquake near Longview
No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.6 explosion was recorded 27 km (17 mi) north-northeast of Longview, WA, at 3:43 pm PDT on 4 August 2020 (22:43 UTC), less than 1 km deep.
USGS: 9 km SSE of Toledo, Washington
92 km (57 mi) N of Portland, OR
- When
- 3:43 pm PDT on 4 August 2020 ()
- Where
- 27 km (17 mi) north-northeast of Longview, WA · earthquakes near Longview
- Magnitude
- M 1.6 (ml)
- Depth
- -0.3 km below the surface
- Felt
- no reports yet
- Nearest
- Cowlitz County, 20 km SSE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2291 days ago
Earthquake alerts for Longview, WA
Get a notification in this browser when USGS records an earthquake near Longview, WA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 12 km (7 mi) from the epicentre. In Longview, 27 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: 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 9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,700,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
- Around the size people start to feel M 3.0 110× the energy of this one
- This earthquake M 1.6 about 9 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 11 earthquakes of M5 or more within 50 km; the five largest:
- 5.7 38 km NNE of Amboy, Washington · 50 km ESE of this epicentre
- 5.2 37 km NNE of Amboy, Washington · 49 km ESE of this epicentre
- 5.2 23 km S of Morton, Washington · 43 km E of this epicentre
- 5.1 38 km NNE of Amboy, Washington · 49 km ESE of this epicentre
- 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 46.3617, -122.7930. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Cowlitz County, WA | 20 km (13 mi) | SSE | earthquakes near Cowlitz County |
| Lewis County, WA | 40 km (25 mi) | NE | earthquakes near Lewis County |
| Wahkiakum County, WA | 49 km (30 mi) | W | earthquakes near Wahkiakum County |
| Columbia County, OR | 52 km (32 mi) | SSW | earthquakes near Columbia County |
| Thurston County, WA | 64 km (40 mi) | N | earthquakes near Thurston County |
| Clark County, WA | 70 km (43 mi) | SSE | earthquakes near Clark County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 2.0 21 km E of Castle Rock, Washington
- 1.7 3 km W of Winlock, Washington
- 1.5 4 km ESE of Chehalis, Washington
- 2.8 21 km E of Castle Rock, Washington
- 1.5 21 km E of Castle Rock, Washington
- 2.5 21 km E of Castle Rock, Washington
- 2.4 9 km SE of Mossyrock, Washington
- 1.5 28 km N of Amboy, Washington
- 1.6 6 km WSW of Napavine, Washington
- 1.7 22 km S of Morton, Washington
- 1.8 20 km SSW of Morton, Washington
- 1.7 16 km NNE of Amboy, Washington
- 1.7 26 km N of Amboy, Washington
- 1.6 4 km NW of Winlock, Washington
- 1.8 2 km N of West Longview, 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.