quarry blast · reviewed by a seismologist
M 1.6md
Earthquake near Santa Venetia, CA
No earthquake was likely felt in Santa Venetia in the 24 hours to 9:26 pm PST (05:26 UTC). The last one was M 1.6, 6 km (4 mi) E, at 11:44 am PST on 10 November 2026, estimated intensity II (weak) in town. Every earthquake near Santa Venetia
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.6 quarry blast was recorded 6 km (4 mi) east-southeast of Santa Venetia, CA, at 11:38 am PDT on 8 April 2021 (18:38 UTC), less than 1 km deep.
USGS: 6km ESE of Santa Venetia, CA
23 km (14 mi) N of San Francisco, CA · in San Rafael, CA
- When
- 11:38 am PDT on 8 April 2021 ()
- Where
- 6 km (4 mi) east-southeast of Santa Venetia, CA · earthquakes near Santa Venetia
- Magnitude
- M 1.6 (md)
- Depth
- -0.0 km below the surface
- Felt
- no reports yet
- Nearest
- Marin County, 27 km WNW
- Nearest mapped fault
- Rodgers Creek fault, 19 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 2040 days ago
Earthquake alerts for Santa Venetia, CA
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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 Santa Venetia, 6 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: San Rafael 7 km, intensity II · San Pablo 10 km, intensity II · Richmond 11 km, intensity II. Estimated for each town centre; each link is that town's own record.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 8.1 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 1,900,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,300,000× the energy of this one
- Around the size people start to feel M 3.0 120× the energy of this one
- This earthquake M 1.6 about 8.1 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 18,000 times the energy of this one.
Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:
- 7.9 The 1906 San Francisco, California Earthquake · 27 km SSW of this epicentre
- 6.0 The 2014 South Napa, California Earthquake · 29 km NNE of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 35 km S of this epicentre
- 5.3 3 km E of Bloomfield, California · 48 km NW of this epicentre
- 5.3 Northern California · 50 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 37.9825, -122.4560. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Marin County, CA | 27 km (17 mi) | WNW | earthquakes near Marin County |
| Contra Costa County, CA | 45 km (28 mi) | E | earthquakes near Contra Costa County |
| Solano County, CA | 55 km (34 mi) | NE | earthquakes near Solano County |
| San Francisco County, CA | 58 km (36 mi) | WSW | earthquakes near San Francisco County |
| Napa County, CA | 59 km (37 mi) | N | earthquakes near Napa County |
| Alameda County, CA | 61 km (38 mi) | SE | earthquakes near Alameda County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
50 earthquakes have been recorded within 50 km since this one.
- 1.5 2km ESE of Berkeley, CA
- 1.5 4km E of Moraga, CA
- 1.8 7km S of Muir Beach, CA
- 1.9 4km SSW of Colma, CA
- 2.3 2km WNW of Concord, CA
- 1.7 2km E of Berkeley, CA
- 2.1 8km S of Muir Beach, CA
- 1.6 8km S of Muir Beach, CA
- 1.9 7km ESE of Roseland, CA
- 1.6 3km NNW of Piedmont, CA
- 2.1 2km ENE of Berkeley, CA
- 1.7 3km WNW of Castro Valley, CA
- 1.9 1km NNW of Crockett, CA
- 2.7 6km SSW of San Ramon, CA
- 3.9 3km N of San Lorenzo, 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.