QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Upper Lake, CA

No earthquake was likely felt in Upper Lake in the 24 hours to 12:17 pm PST (20:17 UTC). The last one was M 1.6, 8 km (5 mi) W, at 4:31 am PST on 10 November 2026, estimated intensity II (weak) in town. Every earthquake near Upper Lake

This page: a magnitude 1.8 earthquake was recorded 19 km (12 mi) northeast of Upper Lake, CA, at 1:09 pm PDT on 20 August 2026 (20:09 UTC), 6.0 km deep.

USGS: 19 km NE of Upper Lake, CA

1:09 pm PDT, Aug 20, 2026 · · 6.0 km deep · released about 13 lb of TNT

Every earthquake near Upper Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Lake County 21 kmGlenn County 47 kmColusa County 48 kmMendocino County 59 kmSonoma County 87 kmNapa County 96 kmSutter County 97 kmYolo County 102 kmTehama County 103 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:09 pm PDT on 20 August 2026 ()
Where
19 km (12 mi) northeast of Upper Lake, CA · earthquakes near Upper Lake
Magnitude
M 1.8 (md)
Depth
6.0 km below the surface
Felt
no reports yet
Nearest
Lake County, 21 km S
Nearest mapped fault
Bartlett Springs fault system, 4 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 72 days ago

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 Upper Lake, 19 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.

Earthquakes near other towns within 30 km: Nice, North Lakeport.

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.

  1. Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 810,000× the energy of this one
  3. Around the size people start to feel M 3.0 72× the energy of this one
  4. 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 5.6 on 2026-06-24 — about 560,000 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

  1. 5.2 6 km ESE of Talmage, California · 34 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 39.2958, -122.7765. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Lake County, CA 21 km (13 mi) S earthquakes near Lake County
Glenn County, CA 47 km (29 mi) NE earthquakes near Glenn County
Colusa County, CA 48 km (30 mi) ESE earthquakes near Colusa County
Mendocino County, CA 59 km (37 mi) WNW earthquakes near Mendocino County
Sonoma County, CA 87 km (54 mi) S earthquakes near Sonoma County
Napa County, CA 96 km (60 mi) SSE earthquakes near Napa County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

52 earthquakes have been recorded within 50 km since this one.

  1. 2.2 6 km N of Redwood Valley, CA
  2. 0.9 8 km WNW of Cobb, CA
  3. 1.0 1 km NNW of Redwood Valley, CA
  4. 1.5 11 km N of Redwood Valley, CA
  5. 1.4 10 km WNW of Cobb, CA
  6. 0.8 11 km WNW of Cobb, CA
  7. 0.8 11 km WNW of Cobb, CA
  8. 0.6 10 km WNW of Cobb, CA
  9. 2.1 10 km WNW of Cobb, CA
  10. 0.7 10 km WNW of Cobb, CA
  11. 1.6 7 km NW of Redwood Valley, CA
  12. 2.6 9 km NW of Redwood Valley, CA
  13. 1.4 6 km ESE of Redwood Valley, CA
  14. 1.7 3 km S of Redwood Valley, CA
  15. 1.1 10 km WNW of Cobb, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.