QuakeIndex

Earthquake · reviewed by a seismologist

M 2.0md

Earthquake near Portola, CA

No earthquake was likely felt in Portola in the 24 hours to 6:03 am PST (14:03 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 2.0 earthquake was recorded 15 km (9 mi) southwest of Portola, CA, at 6:09 pm PDT on 31 March 2021 (01:09 UTC), 9.4 km deep.

USGS: 3km WSW of Whitehawk, CA

65 km (40 mi) WNW of Reno, NV

6:09 pm PDT, Mar 31, 2021 · · 9.4 km deep · released about 35 lb of TNT

Every earthquake near Portola Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sierra County 16 kmPlumas County 38 kmNevada County 49 kmPlacer County 73 kmYuba County 82 kmButte County 88 kmCarson City 94 kmStorey County 95 kmEl Dorado County 103 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
6:09 pm PDT on 31 March 2021 ()
Where
15 km (9 mi) southwest of Portola, CA · earthquakes near Portola
Magnitude
M 2.0 (md)
Depth
9.4 km below the surface
Felt
no reports yet
Nearest
Sierra County, 16 km SSE
Nearest mapped fault
Mohawk Valley 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 2047 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 13 km (8 mi) from the epicentre. In Portola, 15 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 35 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 440,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 310,000× the energy of this one
  3. Around the size people start to feel M 3.0 28× the energy of this one
  4. This earthquake M 2.0 about 35 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 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 6 km WNW of Verdi, California · 46 km ESE of this epicentre
  2. 5.9 West of Downieville, California · 43 km WSW of this epicentre
  3. 5.9 9 km NW of Truckee, California · 44 km SE of this epicentre
  4. 5.6 5 km NE of Loyalton, California · 32 km E of this epicentre
  5. 5.3 11 km N of Soda Springs, California · 35 km SSE 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 39.7095, -120.5783. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sierra County, CA 16 km (10 mi) SSE earthquakes near Sierra County
Plumas County, CA 38 km (23 mi) NNW earthquakes near Plumas County
Nevada County, CA 49 km (30 mi) SSW earthquakes near Nevada County
Placer County, CA 73 km (45 mi) S earthquakes near Placer County
Yuba County, CA 82 km (51 mi) SW earthquakes near Yuba County
Butte County, CA 88 km (55 mi) W earthquakes near Butte County

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

Aftershocks so far

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

  1. 1.5 3 km WNW of Sierra City, California
  2. 2.2 9km E of Little Grass Valley, CA
  3. 1.5 1 km ESE of C-Road, California
  4. 2.0 14km SSW of Loyalton, CA
  5. 1.5 3 km SSE of Greenhorn, California
  6. 2.2 3km WSW of Cromberg, CA
  7. 2.7 5km ENE of East Quincy, CA
  8. 2.1 6km SW of Cromberg, CA
  9. 3.1 14km SSW of Loyalton, CA
  10. 2.1 4km SE of Taylorsville, CA
  11. 2.8 11km NNE of Lake Davis, CA
  12. 1.7 35km WNW of Truckee, CA
  13. 2.1 7km N of Greenhorn, CA
  14. 2.1 1km WNW of Lake Davis, CA
  15. 2.0 19km SW 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.