QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Earthquake near Portola, CA

No earthquake was likely felt in Portola in the 24 hours to 1:05 pm PST (21:05 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 1.5 earthquake was recorded 3 km (2 mi) east of Portola, CA, at 5:43 pm PDT on 30 September 2025 (00:43 UTC), 4.8 km deep.

USGS: 2 km E of Portola, California

58 km (36 mi) WNW of Reno, NV

5:43 pm PDT, Sep 30, 2025 · · 4.8 km deep · released about 5.4 lb of TNT

Every earthquake near Portola Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sierra County 27 kmPlumas County 39 kmNevada County 64 kmPlacer County 87 kmStorey County 88 kmCarson City 94 kmYuba County 98 kmButte County 101 kmLassen County 102 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
5:43 pm PDT on 30 September 2025 ()
Where
3 km (2 mi) east of Portola, CA · earthquakes near Portola
Magnitude
M 1.5 (ml)
Depth
4.8 km below the surface
Felt
no reports yet
Nearest
Sierra County, 27 km SSW
Nearest mapped fault
Mohawk Valley fault, 15 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 407 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 9 km (6 mi) from the epicentre. In Portola, 3 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.

Likely felt in: Portola 3 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 53,000 times the energy of this one.

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 · 42 km SE of this epicentre
  2. 5.9 9 km NW of Truckee, California · 48 km SSE of this epicentre
  3. 5.6 6 km NNE of Doyle, California · 44 km NE of this epicentre
  4. 5.6 5 km NE of Loyalton, California · 23 km ESE of this epicentre
  5. 5.3 11 km N of Soda Springs, California · 42 km S 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 39.8086, -120.4358. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sierra County, CA 27 km (17 mi) SSW earthquakes near Sierra County
Plumas County, CA 39 km (24 mi) WNW earthquakes near Plumas County
Nevada County, CA 64 km (40 mi) SSW earthquakes near Nevada County
Placer County, CA 87 km (54 mi) SSW earthquakes near Placer County
Storey County, NV 88 km (55 mi) ESE earthquakes near Storey County
Carson City, NV 94 km (58 mi) SE earthquakes near Carson City

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

Aftershocks so far

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

  1. 2.2 9 km S of Johnsville, CA
  2. 2.1 7 km NE of Lake Davis, CA
  3. 2.3 9 km NW of Verdi-Mogul, NV
  4. 2.4 4 km NW of Cold Springs, NV
  5. 2.6 8 km NE of Lake Davis, CA
  6. 2.2 15 km SE of Honey Lake, CA
  7. 2.3 8 km NE of Lake Davis, CA
  8. 2.2 8 km NE of Lake Davis, CA
  9. 2.0 5 km SSW of Cromberg, CA
  10. 3.0 4 km WSW of Johnsville, CA
  11. 2.4 5 km NW of Johnsville, CA
  12. 2.1 8 km NE of Lake Davis, CA
  13. 2.2 8 km NE of Lake Davis, CA
  14. 2.1 19 km N of Chilcoot-Vinton, CA
  15. 2.1 16 km SE of Whitehawk, 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.