Earthquake · reviewed by a seismologist
M 3.4mw
Earthquake near Pacheco, CA
No earthquake was likely felt in Pacheco in the 24 hours to 4:03 am PST (12:03 UTC). The last one was M 2.1, 5 km (3 mi) S, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Pacheco
This page: a magnitude 3.4 earthquake was recorded in Pacheco, CA, at 2:36 am PDT on 27 April 2019 (09:36 UTC), 17 km deep. 767 people have reported feeling it to USGS.
USGS: 2km NE of Pacheco, CA
6 km (4 mi) WNW of Concord, CA
- When
- 2:36 am PDT on 27 April 2019 ()
- Where
- in Pacheco, CA · earthquakes near Pacheco
- Magnitude
- M 3.4 (mw)
- Depth
- 17 km below the surface
- Felt
- 767 reports · strongest reported intensity III
- Measured shaking
- intensity IV (ShakeMap)
- Nearest
- Contra Costa County, 13 km SE
- Nearest mapped fault
- Concord fault, under 1 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 288 days ago
Earthquake alerts for Pacheco, CA
Get a notification in this browser when USGS records an earthquake near Pacheco, 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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 53 km (33 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: Pacheco in town, intensity III · Concord 3 km, intensity III · Pleasant Hill 5 km, intensity III · Martinez 7 km, intensity III · Walnut Creek 10 km, intensity III · Benicia 10 km, intensity III · Lafayette 13 km, intensity III · Crockett 15 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 99,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 4,400× the energy of this one
- Magna, Utah 2020 M 5.7 3,100× the energy of this one
- This earthquake M 3.4 about 1.7 tons of TNT
- Around the size people start to feel M 3.0 this one released 3.6× 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 4.4 on 2018-01-04 — about 33 times the energy of this one.
Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 33 km NW of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 31 km SE of this epicentre
- 5.4 South of Elmira, California · 37 km NNE of this epicentre
- 5.4 9 km NE of Livermore, California · 41 km SE of this epicentre
- 5.1 11 km E of Blackhawk, California · 32 km SE 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 37.9952, -122.0605. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Contra Costa County, CA | 13 km (8 mi) | SE | earthquakes near Contra Costa County |
| Solano County, CA | 32 km (20 mi) | NNE | earthquakes near Solano County |
| Alameda County, CA | 41 km (25 mi) | SSE | earthquakes near Alameda County |
| Marin County, CA | 60 km (38 mi) | W | earthquakes near Marin County |
| Napa County, CA | 61 km (38 mi) | NNW | earthquakes near Napa County |
| San Joaquin County, CA | 69 km (43 mi) | E | earthquakes near San Joaquin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
49 earthquakes have been recorded within 50 km since this one.
- 1.7 4km ESE of Oakland, CA
- 1.9 12km NW of Rio Vista, CA
- 2.4 4km NNW of Green Valley, CA
- 1.6 2km E of Berkeley, CA
- 1.6 3km ENE of Pittsburg, CA
- 2.0 3km SSW of Alameda, CA
- 2.5 3km N of San Leandro, CA
- 2.0 5km SSE of Pittsburg, CA
- 1.6 4km ESE of Moraga, CA
- 1.5 3km NE of Alamo, CA
- 1.8 2km NE of San Ramon, CA
- 1.8 2km NE of San Ramon, CA
- 2.0 9km N of Pittsburg, CA
- 1.8 11km N of Bay Point, CA
- 1.5 2km SW of Clayton, 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.