explosion · reviewed by a seismologist
M 1.7ml
Earthquake near Lofall, WA
No earthquake was likely felt in Lofall in the 24 hours to 11:57 pm PST (07:57 UTC). The last one was M 4.2, 46 km (29 mi) S, at 2:05 pm PDT on 29 September 2026, estimated intensity III (weak) in town; 9,329 felt reports to USGS. Every earthquake near Lofall
No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.7 explosion was recorded 6 km (4 mi) north-northwest of Lofall, WA, at 10:54 am PDT on 20 July 2021 (17:54 UTC), less than 1 km deep.
USGS: 6 km NNW of Lofall, Washington
37 km (23 mi) NW of Seattle, WA · 28 km (18 mi) WNW of Shoreline, WA
- When
- 10:54 am PDT on 20 July 2021 ()
- Where
- 6 km (4 mi) north-northwest of Lofall, WA · earthquakes near Lofall
- Magnitude
- M 1.7 (ml)
- Depth
- -0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Kitsap County, 25 km S
- Nearest mapped fault
- Southern Whidbey Island fault, 16 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1941 days ago
Earthquake alerts for Lofall, WA
Get a notification in this browser when USGS records an earthquake near Lofall, 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 Lofall, 6 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: Port Ludlow, Hansville, Poulsbo, Bangor Trident Base, Kingston, Indianola.
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
The largest earthquake within 50 km since 2016 was M 4.1 on 2017-02-23 — about 3,700 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.3 Eastern Olympic Peninsula, Washington · 24 km WSW 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 47.8643, -122.6910. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Kitsap County, WA | 25 km (16 mi) | S | earthquakes near Kitsap County |
| Island County, WA | 33 km (20 mi) | N | earthquakes near Island County |
| Jefferson County, WA | 63 km (39 mi) | W | earthquakes near Jefferson County |
| Mason County, WA | 68 km (42 mi) | SSW | earthquakes near Mason County |
| Snohomish County, WA | 72 km (45 mi) | ENE | earthquakes near Snohomish County |
| King County, WA | 76 km (48 mi) | ESE | earthquakes near King 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.
- 1.6 5 km SW of Port Ludlow, Washington
- 1.8 6 km NNW of Kingston, Washington
- 1.5 8 km ESE of Blyn, Washington
- 1.5 6 km WSW of Erlands Point-Kitsap Lake, Washington
- 1.8 3 km W of Hansville, Washington
- 2.4 3 km W of Hansville, Washington
- 1.8 2 km WNW of Gorst, Washington
- 2.4 0 km ENE of Enetai, Washington
- 2.6 4 km WNW of Quilcene, Washington
- 1.8 6 km SSW of Port Ludlow, Washington
- 2.3 3 km SSW of Silvana, Washington
- 1.5 5 km N of Belfair, Washington
- 2.4 4 km ENE of Camano, Washington
- 1.7 5 km SW of Seattle, Washington
- 1.6 Olympic Peninsula, 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.