QuakeIndex

Earthquake · reviewed by a seismologist

M 2.2md

Earthquake near Portola, CA

No earthquake was likely felt in Portola in the 24 hours to 3:42 am PST (11:42 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 2.2 earthquake was recorded 26 km (16 mi) southwest of Portola, CA, at 8:27 pm PDT on 2 August 2020 (03:27 UTC), less than 1 km deep. 1 person has reported feeling it to USGS.

USGS: 14km SW of Whitehawk, CA

69 km (43 mi) W of Reno, NV

8:27 pm PDT, Aug 2, 2020 · · 0.1 km deep · released about 69 lb of TNT

Every earthquake near Portola Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sierra County 12 kmNevada County 37 kmPlumas County 44 kmPlacer County 62 kmYuba County 71 kmButte County 82 kmCarson City 93 kmEl Dorado County 93 kmStorey County 98 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
8:27 pm PDT on 2 August 2020 ()
Where
26 km (16 mi) southwest of Portola, CA · earthquakes near Portola
Magnitude
M 2.2 (md)
Depth
0.1 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Sierra County, 12 km ESE
Nearest mapped fault
Mohawk Valley fault, 12 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 2292 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 19 km (12 mi) from the epicentre. In Portola, 26 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.

How big was it?

This earthquake released about 69 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.2 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 220,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 150,000× the energy of this one
  3. Around the size people start to feel M 3.0 14× the energy of this one
  4. This earthquake M 2.2 about 69 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 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 6 km WNW of Verdi, California · 49 km E of this epicentre
  2. 5.9 West of Downieville, California · 33 km WSW of this epicentre
  3. 5.9 9 km NW of Truckee, California · 42 km SE of this epicentre
  4. 5.6 5 km NE of Loyalton, California · 40 km ENE of this epicentre
  5. 5.3 11 km N of Soda Springs, California · 30 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 39.6197, -120.6470. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sierra County, CA 12 km (7 mi) ESE earthquakes near Sierra County
Nevada County, CA 37 km (23 mi) SSW earthquakes near Nevada County
Plumas County, CA 44 km (27 mi) NNW earthquakes near Plumas County
Placer County, CA 62 km (39 mi) S earthquakes near Placer County
Yuba County, CA 71 km (44 mi) WSW earthquakes near Yuba County
Butte County, CA 82 km (51 mi) W earthquakes near Butte 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. 2.4 1km NW of Lake Davis, CA
  2. 2.1 1km WNW of Lake Davis, CA
  3. 2.0 1km NW of Lake Davis, CA
  4. 2.8 0km N of Lake Davis, CA
  5. 2.2 1km WNW of Lake Davis, CA
  6. 2.8 0km ESE of Lake Davis, CA
  7. 3.0 0km NNW of Lake Davis, CA
  8. 2.4 0km NNW of Lake Davis, CA
  9. 2.5 0km NW of Lake Davis, CA
  10. 2.1 0km NE of Lake Davis, CA
  11. 2.2 1km WNW of Lake Davis, CA
  12. 2.2 0km WNW of Lake Davis, CA
  13. 2.4 12km NW of Truckee, CA
  14. 2.0 1km NW of Lake Davis, CA
  15. 1.5 15 km SSE of Sierraville, California

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.