Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Healdsburg, CA
No earthquake was likely felt in Healdsburg in the 24 hours to 9:51 pm PST (05:51 UTC). The last one was M 2.6, 22 km (14 mi) NNE, at 4:44 pm PST on 8 November 2026, estimated intensity II (weak) in town. Every earthquake near Healdsburg
This page: a magnitude 1.6 earthquake was recorded 11 km (7 mi) north-northwest of Healdsburg, CA, at 3:45 am PDT on 16 September 2018 (10:45 UTC), 6.7 km deep.
USGS: 10km NNW of Healdsburg, CA
33 km (21 mi) NNW of Santa Rosa, CA · 111 km (69 mi) NNW of San Francisco, CA
- When
- 3:45 am PDT on 16 September 2018 ()
- Where
- 11 km (7 mi) north-northwest of Healdsburg, CA · earthquakes near Healdsburg
- Magnitude
- M 1.6 (md)
- Depth
- 6.7 km below the surface
- Felt
- no reports yet
- Nearest
- Sonoma County, 20 km S
- Nearest mapped fault
- Alexander-Redwood Hill fault, 2 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 2976 days ago
Earthquake alerts for Healdsburg, CA
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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 9 km (6 mi) from the epicentre. In Healdsburg, 11 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: Cloverdale, Windsor, Cobb, Guerneville, Larkfield-Wikiup, Forestville.
How big was it?
This earthquake released about 6.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
- Around the size people start to feel M 3.0 140× the energy of this one
- This earthquake M 1.6 about 6.8 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 140,000 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 5.3 3 km E of Bloomfield, California · 44 km SSE of this epicentre
- 5.3 Northern California · 43 km S of this epicentre
- 5.2 6 km ESE of Talmage, California · 49 km NNW 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 38.7003, -122.9082. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Sonoma County, CA | 20 km (12 mi) | S | earthquakes near Sonoma County |
| Lake County, CA | 47 km (29 mi) | NNE | earthquakes near Lake County |
| Napa County, CA | 55 km (34 mi) | ESE | earthquakes near Napa County |
| Marin County, CA | 74 km (46 mi) | S | earthquakes near Marin County |
| Colusa County, CA | 79 km (49 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 87 km (54 mi) | E | earthquakes near Yolo County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 1.7 7km NE of Rohnert Park, CA
- 2.0 3km SW of Anderson Springs, CA
- 1.5 2km W of Anderson Springs, CA
- 1.7 6km NW of The Geysers, CA
- 2.2 3km SSW of Anderson Springs, CA
- 2.6 3km SSW of Anderson Springs, CA
- 1.8 9km NW of The Geysers, CA
- 1.6 9km NW of The Geysers, CA
- 2.2 9km WNW of Cobb, CA
- 1.7 9km NW of The Geysers, CA
- 3.4 9km WNW of Cobb, CA
- 1.9 3km SW of Anderson Springs, CA
- 2.4 2km SSW of Cobb, CA
- 1.5 4km W of Cobb, CA
- 2.0 3km W of Anderson Springs, 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.