Earthquake · reviewed by a seismologist
M 2.0md
Earthquake near Saint Helena, CA
No earthquake was likely felt in Saint Helena in the 24 hours to 6:47 am PST (14:47 UTC). The last one was M 1.7, 11 km (7 mi) SSW, at 12:33 am PDT on 25 October 2026, estimated intensity II (weak) in town. Every earthquake near Saint Helena
This page: a magnitude 2.0 earthquake was recorded in Saint Helena, CA, at 3:41 am PST on 17 December 2017 (11:41 UTC), 8.4 km deep.
USGS: 2km ENE of Saint Helena, CA
81 km (50 mi) N of San Francisco, CA · 23 km (15 mi) ENE of Santa Rosa, CA
- When
- 3:41 am PST on 17 December 2017 ()
- Where
- in Saint Helena, CA · earthquakes near Saint Helena
- Magnitude
- M 2.0 (md)
- Depth
- 8.4 km below the surface
- Felt
- no reports yet
- Nearest
- Napa County, 11 km E
- Nearest mapped fault
- West Napa fault, 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 3247 days ago
Earthquake alerts for Saint Helena, CA
Get a notification in this browser when USGS records an earthquake near Saint Helena, 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 14 km (9 mi) from the epicentre. 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: Angwin 7 km, intensity II · Kenwood 13 km, intensity II · Calistoga 14 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 32 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 470,000× the energy of this one
- Magna, Utah 2020 M 5.7 330,000× the energy of this one
- Around the size people start to feel M 3.0 30× the energy of this one
- This earthquake M 2.0 about 32 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 5.0 on 2016-12-14 — about 31,000 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 35 km SSE of this epicentre
- 5.3 3 km E of Bloomfield, California · 38 km SW of this epicentre
- 5.3 Northern California · 39 km WSW 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 38.5087, -122.4495. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 11 km (7 mi) | E | earthquakes near Napa County |
| Sonoma County, CA | 42 km (26 mi) | W | earthquakes near Sonoma County |
| Yolo County, CA | 51 km (32 mi) | ENE | earthquakes near Yolo County |
| Solano County, CA | 52 km (32 mi) | ESE | earthquakes near Solano County |
| Marin County, CA | 57 km (35 mi) | SSW | earthquakes near Marin County |
| Lake County, CA | 71 km (44 mi) | NNW | earthquakes near Lake 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.
- 1.6 4km W of Cobb, CA
- 2.1 4km W of Cobb, CA
- 1.5 7km NW of The Geysers, CA
- 1.6 3km S of Cobb, CA
- 1.9 6km NW of The Geysers, CA
- 1.8 6km WNW of The Geysers, CA
- 1.5 9km NW of The Geysers, CA
- 2.1 2km E of The Geysers, CA
- 1.7 4km WNW of The Geysers, CA
- 1.9 14km ESE of Hidden Valley Lake, CA
- 1.8 4km SSE of The Geysers, CA
- 1.8 5km SSE of The Geysers, CA
- 1.9 3km NW of The Geysers, CA
- 2.3 3km NNW of The Geysers, CA
- 1.7 6km NW 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.