Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Ukiah, CA
No earthquake was likely felt in Ukiah in the 24 hours to 4:34 am PST (12:34 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 1.7 earthquake was recorded 36 km (22 mi) east-northeast of Ukiah, CA, at 2:27 am PDT on 5 August 2021 (09:27 UTC), 2.2 km deep.
USGS: 15km SE of Lake Pillsbury, CA
- When
- 2:27 am PDT on 5 August 2021 ()
- Where
- 36 km (22 mi) east-northeast of Ukiah, CA · earthquakes near Ukiah
- Magnitude
- M 1.7 (md)
- Depth
- 2.2 km below the surface
- Felt
- no reports yet
- Nearest
- Lake County, 23 km SSE
- Nearest mapped fault
- Bartlett Springs fault system, 1 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 1919 days ago
Earthquake alerts for Ukiah, CA
Get a notification in this browser when USGS records an earthquake near Ukiah, 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 Ukiah, 36 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: Upper Lake, Nice, North Lakeport, Lakeport.
How big was it?
This earthquake released about 11 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 1,400,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
- Around the size people start to feel M 3.0 89× the energy of this one
- This earthquake M 1.7 about 11 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 120,000 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 · 30 km SW 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 39.3010, -122.8445. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, CA | 23 km (14 mi) | SSE | earthquakes near Lake County |
| Glenn County, CA | 51 km (31 mi) | NE | earthquakes near Glenn County |
| Mendocino County, CA | 53 km (33 mi) | WNW | earthquakes near Mendocino County |
| Colusa County, CA | 54 km (34 mi) | ESE | earthquakes near Colusa County |
| Sonoma County, CA | 87 km (54 mi) | S | earthquakes near Sonoma County |
| Napa County, CA | 99 km (62 mi) | SSE | earthquakes near Napa 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.
- 1.8 8km NNW of Redwood Valley, CA
- 1.8 14km ESE of Lake Pillsbury, CA
- 3.0 14km N of Cloverdale, CA
- 1.5 10km N of Cloverdale, CA
- 1.5 9km NE of Cloverdale, CA
- 2.4 12km N of Lake Pillsbury, CA
- 1.9 14km ESE of Lake Pillsbury, CA
- 2.1 12km SE of Talmage, CA
- 2.0 11km N of Lake Pillsbury, CA
- 2.1 11km N of Lake Pillsbury, CA
- 1.8 11km N of Lake Pillsbury, CA
- 1.6 6km NE of Willits, CA
- 2.0 10km N of Lake Pillsbury, CA
- 1.7 3km ENE of Talmage, CA
- 1.7 10km NNW of Redwood Valley, 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.