QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

Earthquake near Mirrormont, WA

No earthquake was likely felt in Mirrormont in the 24 hours to 6:05 am PST (14:05 UTC). The last one was M 2.6, 14 km (9 mi) ESE, at 6:09 pm PDT on 14 October 2026, estimated intensity II (weak) in town; 46 felt reports to USGS. Every earthquake near Mirrormont

This page: a magnitude 1.8 earthquake was recorded 4 km (2 mi) northeast of Mirrormont, WA, at 4:20 pm PDT on 29 September 2019 (23:20 UTC), 23 km deep.

USGS: 3 km NE of Mirrormont, Washington

14 km (9 mi) SSE of Sammamish, WA · 33 km (21 mi) ESE of Seattle, WA

4:20 pm PDT, Sep 29, 2019 · · 23 km deep · released about 14 lb of TNT

Every earthquake near Mirrormont Felt it? Tell USGS Check my area
10 km30 km60 km120 km N King County 9 kmPierce County 50 kmKitsap County 55 kmSnohomish County 65 kmThurston County 90 kmIsland County 92 kmMason County 92 kmKittitas County 105 kmLewis County 105 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
4:20 pm PDT on 29 September 2019 ()
Where
4 km (2 mi) northeast of Mirrormont, WA · earthquakes near Mirrormont
Magnitude
M 1.8 (ml)
Depth
23 km below the surface
Felt
no reports yet
Nearest
King County, 9 km E
Nearest mapped fault
Seattle fault, 4 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 611 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Mirrormont, 4 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: Hobart, Issaquah, Klahanie, Fall City, Maple Heights-Lake Desire, Snoqualmie.

How big was it?

This earthquake released about 14 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.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 790,000× the energy of this one
  3. Around the size people start to feel M 3.0 70× the energy of this one
  4. This earthquake M 1.8 about 14 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 4.6 on 2019-07-12 — about 16,000 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 6.7 1 km ENE of Dash Point, Washington · 38 km WSW of this epicentre
  2. 5.4 8 km NNE of Lake Marcel-Stillwater, Washington · 32 km NNE of this epicentre
  3. 5.2 9 km NE of Lake Marcel-Stillwater, Washington · 31 km NNE of this epicentre
  4. 5.0 3 km WSW of Des Moines, Washington · 32 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 47.4830, -121.9595. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
King County, WA 9 km (6 mi) E earthquakes near King County
Pierce County, WA 50 km (31 mi) SSW earthquakes near Pierce County
Kitsap County, WA 55 km (34 mi) WNW earthquakes near Kitsap County
Snohomish County, WA 65 km (41 mi) NNE earthquakes near Snohomish County
Thurston County, WA 90 km (56 mi) SW earthquakes near Thurston County
Island County, WA 92 km (57 mi) NW earthquakes near Island 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. 1.8 3 km N of Cathcart, Washington
  2. 1.7 1 km SSE of Riverton, Washington
  3. 1.6 2 km E of Snoqualmie, Washington
  4. 2.4 2 km NE of Mirrormont, Washington
  5. 1.9 2 km SW of Sultan, Washington
  6. 1.9 7 km ENE of Fall City, Washington
  7. 1.8 2 km NE of Mirrormont, Washington
  8. 1.6 3 km NW of Snoqualmie Pass, Washington
  9. 1.5 2 km SSW of Carnation, Washington
  10. 2.0 3 km SE of Southworth, Washington
  11. 1.8 1 km S of Snoqualmie, Washington
  12. 1.8 2 km S of Monroe, Washington
  13. 2.0 2 km SE of Duvall, Washington
  14. 1.8 2 km ENE of Maple Valley, Washington
  15. 1.6 4 km E of Cathcart, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.