Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Rancho Tehama Reserve, CA
No earthquake was likely felt in Rancho Tehama Reserve in the 24 hours to 8:32 pm PST (04:32 UTC). The last one was M 4.0, 74 km (46 mi) SW, at 5:01 am PDT on 28 October 2026, estimated intensity II (weak) in town; 14 felt reports to USGS. Every earthquake near Rancho Tehama Reserve
This page: a magnitude 1.7 earthquake was recorded 40 km (25 mi) west of Rancho Tehama Reserve, CA, at 4:37 am PST on 27 January 2018 (12:37 UTC), 3.3 km deep.
USGS: 36km NNW of Alder Springs, CA
91 km (57 mi) WNW of Chico, CA
- When
- 4:37 am PST on 27 January 2018 ()
- Where
- 40 km (25 mi) west of Rancho Tehama Reserve, CA · earthquakes near Rancho Tehama Reserve
- Magnitude
- M 1.7 (md)
- Depth
- 3.3 km below the surface
- Felt
- no reports yet
- Nearest
- Glenn County, 55 km SE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 3206 days ago
Earthquake alerts for Rancho Tehama Reserve, CA
Get a notification in this browser when USGS records an earthquake near Rancho Tehama Reserve, 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 12 km (7 mi) from the epicentre. In Rancho Tehama Reserve, 40 km away, the estimate is intensity I (not felt). 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 9.6 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 1,600,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
- Around the size people start to feel M 3.0 99× the energy of this one
- This earthquake M 1.7 about 9.6 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
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 33 km NW of Rancho Tehama Reserve, California · 30 km NNE 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 39.9542, -122.8575. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Glenn County, CA | 55 km (34 mi) | SE | earthquakes near Glenn County |
| Tehama County, CA | 57 km (35 mi) | ENE | earthquakes near Tehama County |
| Mendocino County, CA | 77 km (48 mi) | SW | earthquakes near Mendocino County |
| Trinity County, CA | 80 km (50 mi) | NNW | earthquakes near Trinity County |
| Lake County, CA | 95 km (59 mi) | S | earthquakes near Lake County |
| Colusa County, CA | 101 km (63 mi) | SSE | earthquakes near Colusa County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.6 25km W of Rancho Tehama Reserve, CA
- 2.1 14km NNE of Lake Pillsbury, CA
- 1.8 37km NNW of Alder Springs, CA
- 1.7 5km WNW of Covelo, CA
- 1.7 15km N of Alder Springs, CA
- 2.0 44km NNE of Covelo, CA
- 2.0 38km S of Hayfork, CA
- 2.1 38km S of Hayfork, CA
- 2.1 42km NNE of Covelo, CA
- 1.9 25km SE of Hayfork, CA
- 2.5 40km SSE of Hayfork, CA
- 2.3 38km SSE of Hayfork, CA
- 1.8 38km W of Rancho Tehama Reserve, CA
- 1.8 37km WNW of Rancho Tehama Reserve, CA
- 2.1 31km NNW of Alder Springs, 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.