Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Black Point-Green Point, CA
No earthquake was likely felt in Black Point-Green Point in the 24 hours to 3:22 am PST (11:22 UTC). The last one was M 2.4, 6 km (4 mi) WSW, at 6:21 pm PDT on 26 September 2026, estimated intensity II (weak) in town. Every earthquake near Black Point-Green Point
This page: a magnitude 1.8 earthquake was recorded 8 km (5 mi) north-northeast of Black Point-Green Point, CA, at 2:32 pm PDT on 31 August 2021 (21:32 UTC), 7.8 km deep.
USGS: 8km NNE of Black Point-Green Point, CA
12 km (8 mi) NNE of Novato, CA · 44 km (28 mi) N of San Francisco, CA
- When
- 2:32 pm PDT on 31 August 2021 ()
- Where
- 8 km (5 mi) north-northeast of Black Point-Green Point, CA · earthquakes near Black Point-Green Point
- Magnitude
- M 1.8 (md)
- Depth
- 7.8 km below the surface
- Felt
- no reports yet
- Nearest
- Marin County, 28 km WSW
- Nearest mapped fault
- Rodgers Creek 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 1891 days ago
Earthquake alerts for Black Point-Green Point, 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 11 km (7 mi) from the epicentre. In Black Point-Green Point, 8 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.
Likely felt in: Black Point-Green Point 8 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 14 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.
- Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 790,000× the energy of this one
- Around the size people start to feel M 3.0 70× the energy of this one
- This earthquake M 1.8 about 14 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 4.5 on 2019-10-15 — about 11,000 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 7.9 The 1906 San Francisco, California Earthquake · 48 km S of this epicentre
- 6.0 The 2014 South Napa, California Earthquake · 15 km ENE of this epicentre
- 5.3 3 km E of Bloomfield, California · 33 km WNW of this epicentre
- 5.3 Northern California · 35 km WNW 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 38.1760, -122.4725. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Marin County, CA | 28 km (17 mi) | WSW | earthquakes near Marin County |
| Napa County, CA | 39 km (24 mi) | NNE | earthquakes near Napa County |
| Solano County, CA | 48 km (30 mi) | ENE | earthquakes near Solano County |
| Contra Costa County, CA | 54 km (33 mi) | ESE | earthquakes near Contra Costa County |
| Sonoma County, CA | 55 km (34 mi) | NW | earthquakes near Sonoma County |
| San Francisco County, CA | 70 km (43 mi) | SW | earthquakes near San Francisco County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
29 earthquakes have been recorded within 50 km since this one.
- 1.7 10km NE of Napa, CA
- 1.7 14km E of Angwin, CA
- 1.6 7km E of Penngrove, CA
- 2.3 1km W of Kensington, CA
- 2.6 1km W of Kensington, CA
- 2.0 7km W of Kenwood, CA
- 2.3 4km SE of Larkfield-Wikiup, CA
- 2.0 4km ENE of El Sobrante, CA
- 2.8 4km ENE of El Sobrante, CA
- 2.1 4km ENE of El Sobrante, CA
- 1.6 6km E of Vallejo, CA
- 2.1 3km WNW of Crockett, CA
- 2.1 6km SSW of Yountville, CA
- 1.9 5km SW of Pacheco, CA
- 1.8 2km SE of Pacheco, 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.