Earthquake · reviewed by a seismologist
M 4.2mw
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 4.2 earthquake was recorded 3 km (2 mi) south-southwest of Cobb, CA, at 4:57 pm PST on 20 February 2017 (00:57 UTC), 1.3 km deep. 95 people have reported feeling it to USGS.
USGS: 3 km SSW of Cobb, California
39 km (24 mi) N of Santa Rosa, CA · 116 km (72 mi) NNW of San Francisco, CA
- When
- 4:57 pm PST on 20 February 2017 ()
- Where
- 3 km (2 mi) south-southwest of Cobb, CA · earthquakes near Cobb
- Magnitude
- M 4.2 (mw)
- Depth
- 1.3 km below the surface
- Felt
- 95 reports · strongest reported intensity V
- Measured shaking
- intensity V (ShakeMap)
- USGS impact alert
- green
- Nearest
- Sonoma County, 34 km SSW
- Nearest mapped fault
- Konocti Bay fault, 10 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 1786 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 light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
At this magnitude and depth, people at rest would likely notice it out to about 109 km (68 mi) from the epicentre. In Cobb, 3 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 3 km, intensity IV · Clearlake 20 km, intensity III · Healdsburg 24 km, intensity III · Cloverdale 24 km, intensity III · Calistoga 28 km, intensity III · Windsor 29 km, intensity III · Lakeport 32 km, intensity III · Angwin 35 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 26 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 6,500× the energy of this one
- Mineral, Virginia 2011 M 5.8 290× the energy of this one
- Magna, Utah 2020 M 5.7 200× the energy of this one
- This earthquake M 4.2 about 26 tons of TNT
- Around the size people start to feel M 3.0 this one released 55× 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 19 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 · 47 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 38.7958, -122.7353. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Sonoma County, CA | 34 km (21 mi) | SSW | earthquakes near Sonoma County |
| Lake County, CA | 35 km (22 mi) | N | earthquakes near Lake County |
| Napa County, CA | 48 km (30 mi) | SE | earthquakes near Napa County |
| Colusa County, CA | 60 km (38 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 73 km (46 mi) | E | earthquakes near Yolo County |
| Marin County, CA | 83 km (51 mi) | S | earthquakes near Marin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
57 earthquakes have been recorded within 50 km since this one.
- 1.8 8 km WSW of Cobb, California
- 1.8 8 km WSW of Cobb, California
- 1.5 4 km SSW of Cobb, California
- 2.1 5 km SW of Cobb, California
- 1.5 8 km WSW of Cobb, California
- 1.5 10 km W of Cobb, California
- 2.1 7 km W of Middletown, California
- 1.5 6 km W of Cobb, California
- 1.7 4 km SSW of Cobb, California
- 1.5 7 km W of Middletown, California
- 1.6 4 km WNW of Cobb, California
- 1.6 12 km WSW of Cloverdale, California
- 1.7 6km NW of The Geysers, CA
- 1.7 7 km W of Cobb, California
- 2.1 5 km SW of Cobb, California
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.