Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Alta Sierra, CA
No earthquake was likely felt in Alta Sierra in the 24 hours to 10:34 am PST (18:34 UTC). The last one was M 3.1, 14 km (9 mi) ESE, at 2:37 am PDT on 6 October 2026, estimated intensity III (weak) in town; 30 felt reports to USGS. Every earthquake near Alta Sierra
This page: a magnitude 1.8 earthquake was recorded 47 km (29 mi) north-northeast of Alta Sierra, CA, at 12:37 pm PST on 18 December 2021 (20:37 UTC), 4.4 km deep.
USGS: 39km WSW of Olancha, CA
57 km (35 mi) E of Porterville, CA · 104 km (65 mi) NNE of Bakersfield, CA
- When
- 12:37 pm PST on 18 December 2021 ()
- Where
- 47 km (29 mi) north-northeast of Alta Sierra, CA · earthquakes near Alta Sierra
- Magnitude
- M 1.8 (ml)
- Depth
- 4.4 km below the surface
- Felt
- no reports yet
- Nearest
- Tulare County, 35 km WNW
- Nearest mapped fault
- Kern Canyon fault, 3 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 1788 days ago
Earthquake alerts for Alta Sierra, CA
Get a notification in this browser when USGS records an earthquake near Alta Sierra, 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 Alta Sierra, 47 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 13 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 1,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 810,000× the energy of this one
- Around the size people start to feel M 3.0 72× the energy of this one
- This earthquake M 1.8 about 13 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 4.6 on 2019-07-18 — about 21,000 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 5.2 7km ESE of Coso Junction, CA · 50 km ESE of this epicentre
- 5.0 5 km S of Springville, California · 39 km W 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 36.1392, -118.4073. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Tulare County, CA | 35 km (22 mi) | WNW | earthquakes near Tulare County |
| Kern County, CA | 93 km (58 mi) | SSW | earthquakes near Kern County |
| Inyo County, CA | 101 km (63 mi) | ENE | earthquakes near Inyo County |
| Fresno County, CA | 131 km (82 mi) | WNW | earthquakes near Fresno County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
45 earthquakes have been recorded within 50 km since this one.
- 1.8 16km N of Olancha, CA
- 2.0 13km S of Olancha, CA
- 1.6 12km S of Olancha, CA
- 2.2 12km SE of Olancha, CA
- 1.8 12km SE of Olancha, CA
- 1.6 8km NE of Coso Junction, CA
- 2.2 8km NE of Coso Junction, CA
- 2.0 18km WNW of Olancha, CA
- 2.4 5km W of Kernville, CA
- 2.5 8km NNE of Olancha, CA
- 1.9 9km NNE of Olancha, CA
- 1.9 8km NNE of Olancha, CA
- 1.9 30km W of Olancha, CA
- 2.0 8km NNE of Olancha, CA
- 2.1 8km NNE of Olancha, 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.