QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6md

Earthquake near Portola, CA

No earthquake was likely felt in Portola in the 24 hours to 7:08 pm PST (03:08 UTC). The last one was M 2.7, 8 km (5 mi) N, at 8:16 am PST on 10 November 2026, estimated intensity III (weak) in town; 9 felt reports to USGS. Every earthquake near Portola

This page: a magnitude 2.6 earthquake was recorded 7 km (4 mi) north of Portola, CA, at 5:27 pm PDT on 27 May 2021 (00:27 UTC), 3.0 km deep. 3 people have reported feeling it to USGS.

USGS: 0km W of Lake Davis, CA

64 km (40 mi) WNW of Reno, NV

5:27 pm PDT, May 27, 2021 · · 3.0 km deep · released about 260 lb of TNT

Every earthquake near Portola Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Plumas County 33 kmSierra County 33 kmNevada County 68 kmPlacer County 92 kmStorey County 95 kmLassen County 95 kmButte County 99 kmYuba County 100 kmCarson City 101 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
5:27 pm PDT on 27 May 2021 ()
Where
7 km (4 mi) north of Portola, CA · earthquakes near Portola
Magnitude
M 2.6 (md)
Depth
3.0 km below the surface
Felt
3 reports · strongest reported intensity III
Nearest
Plumas County, 33 km WNW
Nearest mapped fault
Mohawk Valley fault, 16 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 1923 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 24 km (15 mi) from the epicentre. In Portola, 7 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: Portola 7 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 260 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 59,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 42,000× the energy of this one
  3. Around the size people start to feel M 3.0 3.7× the energy of this one
  4. This earthquake M 2.6 about 260 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 4.7 on 2021-05-07 — about 1,100 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. 6.0 6 km WNW of Verdi, California · 49 km SE of this epicentre
  2. 5.6 6 km NNE of Doyle, California · 42 km NE of this epicentre
  3. 5.6 5 km NE of Loyalton, California · 29 km SE of this epicentre
  4. 5.3 11 km N of Soda Springs, California · 49 km S of this epicentre
  5. 5.3 4 km S of Doyle, California · 34 km ENE 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 39.8693, -120.4778. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Plumas County, CA 33 km (20 mi) WNW earthquakes near Plumas County
Sierra County, CA 33 km (20 mi) S earthquakes near Sierra County
Nevada County, CA 68 km (42 mi) SSW earthquakes near Nevada County
Placer County, CA 92 km (57 mi) SSW earthquakes near Placer County
Storey County, NV 95 km (59 mi) ESE earthquakes near Storey County
Lassen County, CA 95 km (59 mi) N earthquakes near Lassen County

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

Aftershocks so far

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

  1. 1.6 1 km NNE of Paxton, California
  2. 1.5 1 km WNW of Keddie, California
  3. 1.7 1 km W of Keddie, California
  4. 1.6 0 km E of Paxton, California
  5. 2.8 3km N of Greenhorn, CA
  6. 1.6 5 km NNW of Plumas Eureka (historical), California
  7. 1.5 1 km SW of Spring Garden, California
  8. 2.2 4km NE of Lake Davis, CA
  9. 3.1 10km ESE of Loyalton, CA
  10. 1.5 4 km N of Greenhorn, California
  11. 2.8 15km WSW of Loyalton, CA
  12. 1.7 4 km WNW of Sierra City, California
  13. 1.5 3 km WNW of Sierra City, California
  14. 2.2 16km WSW of Loyalton, CA
  15. 2.1 17km SSW of Loyalton, 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.