QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Chico, WA

No earthquake was likely felt in Chico in the 24 hours to 4:05 am PST (12:05 UTC). The last one was M 4.2, 23 km (15 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 Chico

This page: a magnitude 1.9 earthquake was recorded 7 km (4 mi) west-southwest of Chico, WA, at 5:22 am PDT on 30 April 2018 (12:22 UTC), 26 km deep.

USGS: 6 km WSW of Chico, Washington

33 km (21 mi) W of Seattle, WA

5:22 am PDT, Apr 30, 2018 · · 26 km deep · released about 19 lb of TNT

Every earthquake near Chico Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kitsap County 12 kmMason County 39 kmJefferson County 60 kmIsland County 64 kmThurston County 72 kmKing County 72 kmPierce County 76 kmSnohomish County 93 kmGrays Harbor County 94 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
5:22 am PDT on 30 April 2018 ()
Where
7 km (4 mi) west-southwest of Chico, WA · earthquakes near Chico
Magnitude
M 1.9 (ml)
Depth
26 km below the surface
Felt
no reports yet
Nearest
Kitsap County, 12 km ENE
Nearest mapped fault
Seattle fault, under 1 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 3119 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 Chico, 7 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: Erlands Point-Kitsap Lake, Seabeck, Rocky Point, Silverdale, Navy Yard City, Tracyton.

How big was it?

This earthquake released about 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 790,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 560,000× the energy of this one
  3. Around the size people start to feel M 3.0 50× the energy of this one
  4. This earthquake M 1.9 about 19 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 2,100 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.8 The 2001 Nisqually, Washington Earthquake · 49 km S of this epicentre
  2. 6.7 1 km ENE of Dash Point, Washington · 41 km SE of this epicentre
  3. 6.1 Puget Sound region, Washington · 20 km S of this epicentre
  4. 5.8 Puget Sound area, Washington · 35 km SSW of this epicentre
  5. 5.3 Eastern Olympic Peninsula, Washington · 29 km NNW 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 47.5842, -122.7895. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kitsap County, WA 12 km (8 mi) ENE earthquakes near Kitsap County
Mason County, WA 39 km (24 mi) SW earthquakes near Mason County
Jefferson County, WA 60 km (38 mi) WNW earthquakes near Jefferson County
Island County, WA 64 km (40 mi) N earthquakes near Island County
Thurston County, WA 72 km (45 mi) S earthquakes near Thurston County
King County, WA 72 km (45 mi) E earthquakes near King County

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

Aftershocks so far

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

  1. 2.3 0 km ESE of Riverton, Washington
  2. 1.9 0 km SE of Normandy Park, Washington
  3. 1.8 1 km NE of Normandy Park, Washington
  4. 1.6 0 km E of Normandy Park, Washington
  5. 2.3 1 km NNE of Enetai, Washington
  6. 2.8 8 km SW of Skokomish, Washington
  7. 1.6 3 km W of Federal Way, Washington
  8. 1.8 1 km E of Browns Point, Washington
  9. 1.8 7 km ESE of Quilcene, Washington
  10. 1.7 6 km W of Lofall, Washington
  11. 1.9 3 km SSE of Port Ludlow, Washington
  12. 2.1 10 km NNE of Quilcene, Washington
  13. 1.7 3 km E of Home, Washington
  14. 2.1 5 km SW of Clinton, Washington
  15. 2.2 1 km SE of Bethel, 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.