explosion · reviewed by a seismologist
M 1.8ml
Earthquake near Saint Helens, OR
No earthquake was likely felt in Saint Helens in the 24 hours to 6:18 am PST (14:18 UTC). The last one was M 3.0, 5 km (3 mi) WNW, at 7:25 am PDT on 22 October 2026, estimated intensity II (weak) in town; 113 felt reports to USGS. Every earthquake near Saint Helens
No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.8 explosion was recorded 2 km (1 mi) south of Saint Helens, OR, at 1:55 pm PDT on 18 May 2021 (20:55 UTC), less than 1 km deep.
USGS: 2 km S of Saint Helens, Oregon
36 km (23 mi) NNW of Portland, OR · 28 km (18 mi) NW of Vancouver, WA
- When
- 1:55 pm PDT on 18 May 2021 ()
- Where
- 2 km (1 mi) south of Saint Helens, OR · earthquakes near Saint Helens
- Magnitude
- M 1.8 (ml)
- Depth
- -0.3 km below the surface
- Felt
- no reports yet
- Nearest
- Columbia County, 24 km WNW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 614 days ago
Earthquake alerts for Saint Helens, OR
Get a notification in this browser when USGS records an earthquake near Saint Helens, OR. 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 13 km (8 mi) from the epicentre. In Saint Helens, 2 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: Warren, Columbia City, Ridgefield, Woodland, La Center, Scappoose.
USGS catalogues this as explosion, not an earthquake.
How big was it?
This earthquake released about 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 810,000× the energy of this one
- Around the size people start to feel M 3.0 72× the energy of this one
- This earthquake M 1.8 about 13 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 2 earthquakes of M5 or more within 50 km:
- 5.2 5 km E of Bridgeton, Oregon · 32 km SSE of this epicentre
- 5.0 3 km SW of Portland, Oregon · 39 km SSE 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 45.8452, -122.8102. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Columbia County, OR | 24 km (15 mi) | WNW | earthquakes near Columbia County |
| Clark County, WA | 26 km (16 mi) | ESE | earthquakes near Clark County |
| Washington County, OR | 39 km (24 mi) | SW | earthquakes near Washington County |
| Cowlitz County, WA | 40 km (25 mi) | NNE | earthquakes near Cowlitz County |
| Multnomah County, OR | 45 km (28 mi) | SE | earthquakes near Multnomah County |
| Wahkiakum County, WA | 69 km (43 mi) | NW | earthquakes near Wahkiakum County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
59 earthquakes have been recorded within 50 km since this one.
- 1.7 3 km E of Prescott, Oregon
- 1.6 3 km WSW of Yacolt, Washington
- 1.8 8 km S of Scappoose, Oregon
- 1.8 3 km WNW of Saint Helens, Oregon
- 1.7 4 km WSW of Yacolt, Washington
- 1.5 6 km ENE of Prescott, Oregon
- 1.7 7 km ENE of Prescott, Oregon
- 1.6 3 km E of Battle Ground, Washington
- 1.7 3 km NNE of La Center, Washington
- 1.7 Washington-Oregon border region
- 2.0 19 km N of Amboy, Washington
- 2.1 9 km ENE of Kalama, Washington
- 1.6 8 km SW of Aloha, Oregon
- 1.7 4 km ENE of Lewisville, Washington
- 1.6 3 km W of Yacolt, 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.