Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Portola, CA
No earthquake was likely felt in Portola in the 24 hours to 2:50 am PST (10:50 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 1.8 earthquake was recorded 17 km (11 mi) west-northwest of Portola, CA, at 5:42 am PDT on 30 April 2019 (12:42 UTC), 12 km deep.
USGS: 2 km E of Cromberg, California
77 km (48 mi) WNW of Reno, NV
- When
- 5:42 am PDT on 30 April 2019 ()
- Where
- 17 km (11 mi) west-northwest of Portola, CA · earthquakes near Portola
- Magnitude
- M 1.8 (ml)
- Depth
- 12 km below the surface
- Felt
- no reports yet
- Nearest
- Plumas County, 20 km NW
- Nearest mapped fault
- Mohawk Valley fault, 2 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 2753 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 6 km (4 mi) from the epicentre. In Portola, 17 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 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 710,000× the energy of this one
- Around the size people start to feel M 3.0 63× the energy of this one
- This earthquake M 1.8 about 15 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 10,000 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 5.9 West of Downieville, California · 50 km SW of this epicentre
- 5.6 5 km NE of Loyalton, California · 42 km ESE of this epicentre
- 5.3 4 km S of Doyle, California · 48 km ENE of this epicentre
- 5.2 3 km N of Blairsden, California · 7 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 39.8635, -120.6575. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Plumas County, CA | 20 km (13 mi) | NW | earthquakes near Plumas County |
| Sierra County, CA | 34 km (21 mi) | SSE | earthquakes near Sierra County |
| Nevada County, CA | 64 km (40 mi) | S | earthquakes near Nevada County |
| Butte County, CA | 84 km (52 mi) | WSW | earthquakes near Butte County |
| Yuba County, CA | 88 km (55 mi) | SW | earthquakes near Yuba County |
| Placer County, CA | 89 km (55 mi) | S | earthquakes near Placer County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
38 earthquakes have been recorded within 50 km since this one.
- 1.9 10km N of Spring Garden, CA
- 2.3 5km NNE of Little Grass Valley, CA
- 2.1 6km S of Bucks Lake, CA
- 2.1 8km W of La Porte, CA
- 2.3 22km SW of Whitehawk, CA
- 2.8 8km WNW of Lake Davis, CA
- 1.5 3km ESE of Canyondam, CA
- 1.8 5km ESE of Taylorsville, CA
- 1.8 5km ESE of Taylorsville, CA
- 1.6 6 km S of Taylorsville, California
- 1.6 8km W of La Porte, CA
- 1.5 8 km ESE of Milford, California
- 1.5 2km SW of Canyondam, CA
- 2.8 1km WNW of Twain, CA
- 1.5 6 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
- 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.