Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Forest Ranch, CA
No earthquake was likely felt in Forest Ranch in the 24 hours to 4:17 am PST (12:17 UTC). The last one was M 5.6, 145 km (90 mi) WSW, at 8:10 am PDT on 24 June 2026, estimated intensity III (weak) in town; 5,311 felt reports to USGS. Every earthquake near Forest Ranch
This page: a magnitude 1.7 earthquake was recorded 30 km (18 mi) north-northwest of Forest Ranch, CA, at 5:59 am PDT on 6 April 2021 (12:59 UTC), 16 km deep.
USGS: 30km NNW of Forest Ranch, CA
42 km (26 mi) N of Chico, CA
- When
- 5:59 am PDT on 6 April 2021 ()
- Where
- 30 km (18 mi) north-northwest of Forest Ranch, CA · earthquakes near Forest Ranch
- Magnitude
- M 1.7 (md)
- Depth
- 16 km below the surface
- Felt
- no reports yet
- Nearest
- Tehama County, 38 km W
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2043 days ago
Earthquake alerts for Forest Ranch, CA
Get a notification in this browser when USGS records an earthquake near Forest Ranch, 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 it was probably too small to be felt, even directly above it. In Forest Ranch, 30 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 12 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.
- Mineral, Virginia 2011 M 5.8 1,300,000× the energy of this one
- Magna, Utah 2020 M 5.7 900,000× the energy of this one
- Around the size people start to feel M 3.0 80× the energy of this one
- This earthquake M 1.7 about 12 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 one earthquake of M5 or more within 50 km:
- 5.5 15 km NE of Mineral, California · 44 km NE 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 40.1365, -121.7813. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Tehama County, CA | 38 km (24 mi) | W | earthquakes near Tehama County |
| Butte County, CA | 55 km (34 mi) | SSE | earthquakes near Butte County |
| Shasta County, CA | 73 km (45 mi) | NNW | earthquakes near Shasta County |
| Glenn County, CA | 80 km (49 mi) | SW | earthquakes near Glenn County |
| Plumas County, CA | 83 km (52 mi) | E | earthquakes near Plumas County |
| Yuba County, CA | 103 km (64 mi) | SSE | earthquakes near Yuba 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.
- 1.5 8km SSE of Mineral, CA
- 1.6 12km W of Chester, CA
- 1.7 7km SSE of Mineral, CA
- 1.6 12km N of Mineral, CA
- 1.9 3km NE of Viola, CA
- 1.6 9km S of Mineral, CA
- 2.1 14km ESE of Viola, CA
- 2.9 6km NNE of Hamilton City, CA
- 1.9 13km WSW of Almanor, CA
- 1.9 9km WSW of Chester, CA
- 1.5 12km ESE of Viola, CA
- 2.0 9km WSW of Chester, CA
- 1.5 12km ESE of Viola, CA
- 1.9 10km WSW of Chester, CA
- 2.5 6km NW of Chico, 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
- 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.