QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

2 km NNE of Portola, California

· 6.4 km deep · released about 11 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sierra County 29 kmPlumas County 36 kmNevada County 65 kmPlacer County 88 kmStorey County 91 kmCarson City 97 kmYuba County 98 kmLassen County 99 kmButte County 99 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
Magnitude
M 1.7 (ml)
Depth
6.4 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Sierra County, 29 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 738 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 11 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 89× the energy of this one
  4. This earthquake M 1.7 about 11 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.

Where

Epicentre 39.8312, -120.4596. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Sierra County, CA 29 km (18 mi) N of here earthquakes near Sierra County
Plumas County, CA 36 km (22 mi) ESE of here earthquakes near Plumas County
Nevada County, CA 65 km (40 mi) NNE of here earthquakes near Nevada County
Placer County, CA 88 km (55 mi) NNE of here earthquakes near Placer County
Storey County, NV 91 km (57 mi) WNW of here earthquakes near Storey County
Carson City, NV 97 km (60 mi) NW of here earthquakes near Carson City

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

Aftershocks so far

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

  1. 2.5 8 km NE of Lake Davis, CA
  2. 1.9 8 km NE of Lake Davis, CA
  3. 2.0 19 km S of Johnsville, CA
  4. 1.9 8 km N of Spring Garden, CA
  5. 2.2 13 km NE of Lake Davis, CA
  6. 2.4 6 km SW of Cold Springs, NV
  7. 2.4 5 km NW of Johnsville, CA
  8. 2.1 5 km SSW of Cromberg, CA
  9. 2.5 21 km NE of Lake Davis, CA
  10. 2.4 12 km SSW of Johnsville, CA
  11. 2.1 17 km SE of Honey Lake, CA
  12. 2.5 18 km S of Loyalton, CA
  13. 2.7 9 km WNW of Lake Davis, CA
  14. 1.8 11 km N of Lake Davis, CA
  15. 2.1 2 km SSW of Plumas Eureka, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.7 on 2021-05-07 — it released about 27,000 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.