Earthquake · reviewed by a seismologist
M 3.5mw
Earthquake near Cobb, CA
Yes: an earthquake was likely felt in Cobb in the last 24 hours. M 1.6, 4 km (2 mi) W of Cobb, at 1:30 pm PST on 11 November 2026 (21:30 UTC); the estimated shaking in Cobb was intensity II (weak). Every earthquake near Cobb
This page: a magnitude 3.5 earthquake was recorded 4 km (2 mi) west of Cobb, CA, at 12:37 am PDT on 7 April 2018 (07:37 UTC), less than 1 km deep. 28 people have reported feeling it to USGS.
USGS: 4km W of Cobb, CA
43 km (27 mi) N of Santa Rosa, CA · 120 km (75 mi) NNW of San Francisco, CA
- When
- 12:37 am PDT on 7 April 2018 ()
- Where
- 4 km (2 mi) west of Cobb, CA · earthquakes near Cobb
- Magnitude
- M 3.5 (mw)
- Depth
- 0.8 km below the surface
- Felt
- 28 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- Nearest
- Lake County, 31 km N
- Nearest mapped fault
- Konocti Bay fault, 8 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 3057 days ago
Earthquake alerts for Cobb, CA
Get a notification in this browser when USGS records an earthquake near Cobb, 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 63 km (39 mi) from the epicentre. In Cobb, 4 km away, the estimate is intensity IV (light). 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.
Likely felt in: Cobb 4 km, intensity IV · Clearlake 19 km, intensity III · Cloverdale 22 km, intensity III · Healdsburg 26 km, intensity III · Lakeport 27 km, intensity II · Windsor 31 km, intensity II · Calistoga 32 km, intensity II · Angwin 39 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 2.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 65,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 2,900× the energy of this one
- Magna, Utah 2020 M 5.7 2,100× the energy of this one
- This earthquake M 3.5 about 2.6 tons of TNT
- Around the size people start to feel M 3.0 this one released 5.4× more
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 5.0 on 2016-12-14 — about 190 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 · 43 km NW 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 38.8265, -122.7677. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, CA | 31 km (19 mi) | N | earthquakes near Lake County |
| Sonoma County, CA | 36 km (23 mi) | SSW | earthquakes near Sonoma County |
| Napa County, CA | 52 km (32 mi) | SE | earthquakes near Napa County |
| Colusa County, CA | 60 km (37 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 77 km (48 mi) | ESE | earthquakes near Yolo County |
| Marin County, CA | 86 km (54 mi) | S | earthquakes near Marin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
58 earthquakes have been recorded within 50 km since this one.
- 1.7 6km W of Cobb, CA
- 1.8 6km NW of The Geysers, CA
- 1.7 6km WNW of The Geysers, CA
- 1.7 5km NW of The Geysers, CA
- 1.9 9km NW of The Geysers, CA
- 2.4 3km WNW of The Geysers, CA
- 1.5 5km NW of The Geysers, CA
- 1.7 5km NW of The Geysers, CA
- 1.5 7km NW of The Geysers, CA
- 1.7 6km E of Clearlake Oaks, CA
- 1.5 7km NW of The Geysers, CA
- 2.5 7km NW of The Geysers, CA
- 1.9 7km NW of The Geysers, CA
- 2.1 6km WNW of The Geysers, CA
- 1.8 6km WNW of The Geysers, 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.