QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

Earthquake near Graham, WA

No earthquake was likely felt in Graham in the 24 hours to 9:02 pm PST (05:02 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

This page: a magnitude 1.7 earthquake was recorded 45 km (28 mi) southeast of Graham, WA, at 10:40 am PDT on 20 October 2023 (17:40 UTC), 3.2 km deep.

USGS: Washington

10:40 am PDT, Oct 20, 2023 · · 3.2 km deep · released about 11 lb of TNT

10 km30 km60 km120 km N Pierce County 39 kmLewis County 42 kmThurston County 75 kmSkamania County 81 kmKing County 82 kmCowlitz County 87 kmYakima County 94 kmKittitas County 101 kmKitsap County 114 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
10:40 am PDT on 20 October 2023 ()
Where
45 km (28 mi) southeast of Graham, WA · earthquakes near Graham
Magnitude
M 1.7 (ml)
Depth
3.2 km below the surface
Felt
no reports yet
Nearest
Pierce County, 39 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1119 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 12 km (7 mi) from the epicentre. In Graham, 45 km away, the estimate is intensity I (not felt). 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.

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.

  1. Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 970,000× the energy of this one
  3. Around the size people start to feel M 3.0 86× the energy of this one
  4. 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.0 23 km ESE of Packwood, Washington · 45 km SE 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 46.7548, -121.8848. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Pierce County, WA 39 km (24 mi) NNW earthquakes near Pierce County
Lewis County, WA 42 km (26 mi) WSW earthquakes near Lewis County
Thurston County, WA 75 km (46 mi) WNW earthquakes near Thurston County
Skamania County, WA 81 km (51 mi) S earthquakes near Skamania County
King County, WA 82 km (51 mi) N earthquakes near King County
Cowlitz County, WA 87 km (54 mi) SW earthquakes near Cowlitz County

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

Aftershocks so far

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

  1. 1.9 23 km ENE of Ashford, Washington
  2. 1.6 22 km SSE of Packwood, Washington
  3. 1.8 13 km NE of Ashford, Washington
  4. 1.6 6 km ENE of Kapowsin, Washington
  5. 1.8 15 km SW of Packwood, Washington
  6. 1.7 7 km S of Crocker, Washington
  7. 1.7 2 km SE of Kapowsin, Washington
  8. 1.6 12 km ESE of Enumclaw, Washington
  9. 2.2 13 km NNE of Ashford, Washington
  10. 1.5 1 km SSE of Kapowsin, Washington
  11. 1.9 5 km E of Enumclaw, Washington
  12. 1.6 1 km WNW of Kapowsin, Washington
  13. 1.6 24 km NNE of Packwood, Washington
  14. 1.9 6 km E of Mossyrock, Washington
  15. 1.5 2 km ESE of Buckley, 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.