Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Ukiah, CA
No earthquake was likely felt in Ukiah in the 24 hours to 7:41 am PST (15:41 UTC). The last one was M 1.5, 5 km (3 mi) E, at 3:26 am PST on 12 November 2026, estimated intensity II (weak) in town. Every earthquake near Ukiah
This page: a magnitude 1.8 earthquake was recorded 37 km (23 mi) northeast of Ukiah, CA, at 10:28 am PDT on 21 June 2021 (17:28 UTC), 5.0 km deep.
USGS: 2km NNW of Lake Pillsbury, CA
- When
- 10:28 am PDT on 21 June 2021 ()
- Where
- 37 km (23 mi) northeast of Ukiah, CA · earthquakes near Ukiah
- Magnitude
- M 1.8 (md)
- Depth
- 5.0 km below the surface
- Felt
- no reports yet
- Nearest
- Lake County, 40 km SSE
- Nearest mapped fault
- Bartlett Springs fault system, 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 1968 days ago
Earthquake alerts for Ukiah, CA
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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 Ukiah, 37 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.
Earthquakes near other towns within 30 km: Redwood Valley, Upper Lake.
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 1,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 840,000× the energy of this one
- Around the size people start to feel M 3.0 75× 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 5.1 on 2016-08-10 — about 100,000 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.2 6 km ESE of Talmage, California · 37 km SSW 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 39.4278, -122.9640. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, CA | 40 km (25 mi) | SSE | earthquakes near Lake County |
| Mendocino County, CA | 41 km (26 mi) | W | earthquakes near Mendocino County |
| Glenn County, CA | 52 km (32 mi) | ENE | earthquakes near Glenn County |
| Colusa County, CA | 68 km (43 mi) | ESE | earthquakes near Colusa County |
| Tehama County, CA | 100 km (62 mi) | NE | earthquakes near Tehama County |
| Sonoma County, CA | 100 km (62 mi) | S | earthquakes near Sonoma 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.
- 2.4 13km WNW of Alder Springs, CA
- 2.4 11km W of Alder Springs, CA
- 1.9 13km W of Alder Springs, CA
- 1.7 12km W of Alder Springs, CA
- 2.7 12km W of Alder Springs, CA
- 2.9 12km W of Alder Springs, CA
- 2.1 12km W of Alder Springs, CA
- 1.9 13km W of Alder Springs, CA
- 2.1 13km W of Alder Springs, CA
- 2.1 12km W of Alder Springs, CA
- 1.8 12km W of Alder Springs, CA
- 2.8 12km W of Alder Springs, CA
- 2.6 12km WNW of Alder Springs, CA
- 3.7 12km W of Alder Springs, CA
- 2.0 12km W 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.