Earthquake · reviewed by a seismologist
M 1.6ml
Earthquake near Portola, CA
No earthquake was likely felt in Portola in the 24 hours to 4:34 pm PST (00:34 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 1.6 earthquake was recorded 15 km (10 mi) northwest of Portola, CA, at 12:03 pm PDT on 25 May 2021 (19:03 UTC), 7.3 km deep.
USGS: 7 km ENE of Cromberg, California
76 km (47 mi) WNW of Reno, NV
- When
- 12:03 pm PDT on 25 May 2021 ()
- Where
- 15 km (10 mi) northwest of Portola, CA · earthquakes near Portola
- Magnitude
- M 1.6 (ml)
- Depth
- 7.3 km below the surface
- Felt
- no reports yet
- Nearest
- Plumas County, 21 km WNW
- Nearest mapped fault
- Mohawk Valley fault, 7 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 1997 days ago
Earthquake alerts for Portola, CA
Get a notification in this browser when USGS records an earthquake near Portola, CA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 8 km (5 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.
Earthquakes near other towns within 30 km: East Quincy, Quincy.
How big was it?
This earthquake released about 7.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
- Around the size people start to feel M 3.0 130× the energy of this one
- This earthquake M 1.6 about 7.6 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 4.5 on 2016-08-04 — about 21,000 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 5.6 5 km NE of Loyalton, California · 40 km ESE of this epicentre
- 5.3 4 km S of Doyle, California · 44 km ENE of this epicentre
- 5.2 3 km N of Blairsden, California · 9 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 39.8922, -120.6136. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Plumas County, CA | 21 km (13 mi) | WNW | earthquakes near Plumas County |
| Sierra County, CA | 36 km (22 mi) | SSE | earthquakes near Sierra County |
| Nevada County, CA | 67 km (42 mi) | SSW | earthquakes near Nevada County |
| Butte County, CA | 88 km (55 mi) | WSW | earthquakes near Butte County |
| Lassen County, CA | 92 km (57 mi) | N | earthquakes near Lassen County |
| Placer County, CA | 93 km (58 mi) | S | earthquakes near Placer County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
32 earthquakes have been recorded within 50 km since this one.
- 2.2 15km WSW of Loyalton, CA
- 2.4 16km WSW of Loyalton, CA
- 3.3 16km WSW of Loyalton, CA
- 2.7 16km WSW of Loyalton, CA
- 1.6 2 km WNW of Sierraville, California
- 2.1 16km WSW of Loyalton, CA
- 2.1 24km SSW of Loyalton, CA
- 2.3 10km WNW of Little Grass Valley, CA
- 1.5 5km E of Caribou, CA
- 1.5 2 km SE of Spring Garden, California
- 1.7 2 km SSW of Crescent Mills, California
- 1.5 3 km WNW of Sierra City, California
- 2.2 9km E of Little Grass Valley, CA
- 2.0 3km S of Canyondam, CA
- 1.5 1 km ESE of C-Road, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.