QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5md

Earthquake near Larkfield-Wikiup, CA

No earthquake was likely felt in Larkfield-Wikiup in the 24 hours to 5:10 am PST (13:10 UTC). The last one was M 1.9, 8 km (5 mi) ESE, at 2:01 pm PDT on 23 October 2026, estimated intensity II (weak) in town. Every earthquake near Larkfield-Wikiup

This page: a magnitude 2.5 earthquake was recorded 3 km (2 mi) east-southeast of Larkfield-Wikiup, CA, at 11:11 am PDT on 27 August 2021 (18:11 UTC), 6.6 km deep. 122 people have reported feeling it to USGS.

USGS: 3km ESE of Larkfield-Wikiup, CA

6 km (4 mi) NNW of Santa Rosa, CA

11:11 am PDT, Aug 27, 2021 · · 6.6 km deep · released about 140 lb of TNT

Every earthquake near Larkfield-Wikiup Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sonoma County 18 kmNapa County 35 kmMarin County 50 kmLake County 68 kmSolano County 73 kmYolo County 74 kmColusa County 86 kmSan Francisco County 90 kmContra Costa County 93 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
11:11 am PDT on 27 August 2021 ()
Where
3 km (2 mi) east-southeast of Larkfield-Wikiup, CA · earthquakes near Larkfield-Wikiup
Magnitude
M 2.5 (md)
Depth
6.6 km below the surface
Felt
122 reports · strongest reported intensity III
Nearest
Sonoma County, 18 km W
Nearest mapped fault
Rodgers Creek 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 1832 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 21 km (13 mi) from the epicentre. In Larkfield-Wikiup, 3 km away, the estimate is intensity III (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.

Likely felt in: Santa Rosa 7 km, intensity III · Windsor 10 km, intensity II · Calistoga 15 km, intensity II · Healdsburg 18 km, intensity II · Rohnert Park 18 km, intensity II · Kenwood 18 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 140 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 110,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 75,000× the energy of this one
  3. Around the size people start to feel M 3.0 6.7× the energy of this one
  4. This earthquake M 2.5 about 140 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 5.0 on 2016-12-14 — about 6,900 times the energy of this one.

Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:

  1. 6.0 The 2014 South Napa, California Earthquake · 48 km SE of this epicentre
  2. 5.3 3 km E of Bloomfield, California · 22 km SSW of this epicentre
  3. 5.3 Northern California · 22 km SSW 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 38.5003, -122.7237. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sonoma County, CA 18 km (11 mi) W earthquakes near Sonoma County
Napa County, CA 35 km (22 mi) E earthquakes near Napa County
Marin County, CA 50 km (31 mi) S earthquakes near Marin County
Lake County, CA 68 km (42 mi) N earthquakes near Lake County
Solano County, CA 73 km (45 mi) ESE earthquakes near Solano County
Yolo County, CA 74 km (46 mi) ENE earthquakes near Yolo County

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

Aftershocks so far

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

  1. 1.6 3km SE of The Geysers, CA
  2. 1.6 3km SW of Anderson Springs, CA
  3. 1.7 3km NNW of The Geysers, CA
  4. 1.7 6km NW of The Geysers, CA
  5. 1.7 6km NW of The Geysers, CA
  6. 1.7 3km SW of Anderson Springs, CA
  7. 2.6 3km NW of The Geysers, CA
  8. 1.6 10km NE of Healdsburg, CA
  9. 1.8 3km SE of Larkfield-Wikiup, CA
  10. 1.5 0km WNW of The Geysers, CA
  11. 2.0 9km WNW of The Geysers, CA
  12. 1.5 5km NW of The Geysers, CA
  13. 1.6 2km NW of Anderson Springs, CA
  14. 2.4 5km WNW of The Geysers, CA
  15. 1.8 3km ENE of The Geysers, CA

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.