QuakeIndex

explosion · reviewed by a seismologist

M 2.1ml

Earthquake near Graham, WA

No earthquake was likely felt in Graham in the 24 hours to 8:47 pm PST (04:47 UTC). The last one was M 1.6, 5 km (3 mi) SE, at 11:47 am PST on 9 November 2026, estimated intensity II (weak) in town. Every earthquake near Graham

No: USGS classifies this as a explosion, not an earthquake. A magnitude 2.1 explosion was recorded in Graham, WA, at 11:04 am PDT on 27 August 2019 (18:04 UTC), less than 1 km deep. 1 person has reported feeling it to USGS.

USGS: Puget Sound region, Washington

63 km (39 mi) S of Seattle, WA · 22 km (14 mi) ESE of Lakewood, WA

11:04 am PDT, Aug 27, 2019 · · -0.8 km deep · released about 49 lb of TNT

Every earthquake near Graham Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Pierce County 10 kmThurston County 44 kmLewis County 53 kmKing County 59 kmKitsap County 71 kmMason County 75 kmCowlitz County 100 kmGrays Harbor County 117 kmSkamania County 117 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
11:04 am PDT on 27 August 2019 ()
Where
in Graham, WA · earthquakes near Graham
Magnitude
M 2.1 (ml)
Depth
-0.8 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Pierce County, 10 km E
Nearest mapped fault
Tacoma fault, 21 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 2634 days ago

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 18 km (11 mi) from the epicentre. 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.

Likely felt in: Graham in town, intensity III · South Hill 10 km, intensity II · Puyallup 15 km, intensity II · Bonney Lake 15 km, intensity II · Parkland 16 km, intensity II. Estimated for each town centre; each link is that town's own record.

USGS catalogues this as explosion, not an earthquake.

How big was it?

This earthquake released about 49 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 310,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 220,000× the energy of this one
  3. Around the size people start to feel M 3.0 19× the energy of this one
  4. This earthquake M 2.1 about 49 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 4 earthquakes of M5 or more within 50 km:

  1. 6.8 The 2001 Nisqually, Washington Earthquake · 35 km WNW of this epicentre
  2. 6.7 4 km WNW of Roy, Washington · 24 km W of this epicentre
  3. 6.7 1 km ENE of Dash Point, Washington · 32 km NNW of this epicentre
  4. 5.0 3 km WSW of Des Moines, Washington · 37 km N 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 47.0552, -122.2830. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Pierce County, WA 10 km (6 mi) E earthquakes near Pierce County
Thurston County, WA 44 km (27 mi) WSW earthquakes near Thurston County
Lewis County, WA 53 km (33 mi) S earthquakes near Lewis County
King County, WA 59 km (37 mi) NE earthquakes near King County
Kitsap County, WA 71 km (44 mi) NNW earthquakes near Kitsap County
Mason County, WA 75 km (47 mi) WNW earthquakes near Mason County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

45 earthquakes have been recorded within 50 km since this one.

  1. 1.6 1 km NE of Artondale, Washington
  2. 1.5 22 km ENE of Ashford, Washington
  3. 1.7 12 km W of Greenwater, Washington
  4. 2.3 4 km NNW of Lakeland North, Washington
  5. 2.7 2 km S of Ravensdale, Washington
  6. 1.7 3 km WNW of Wauna, Washington
  7. 1.8 23 km ENE of Ashford, Washington
  8. 1.8 10 km ESE of Enumclaw, Washington
  9. 2.1 1 km SW of Home, Washington
  10. 2.4 1 km SSW of Home, Washington
  11. 1.6 2 km WSW of Home, Washington
  12. 2.7 3 km S of Home, Washington
  13. 1.7 13 km W of Greenwater, Washington
  14. 1.8 8 km E of Ashford, Washington
  15. 1.7 1 km SSE of Riverton, 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.