Earthquake · reviewed by a seismologist
M 4.3mw
Earthquake near Byron, CA
No earthquake was likely felt in Byron in the 24 hours to 8:29 pm PST (04:29 UTC). The last one was M 3.5, 53 km (33 mi) SSE, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Byron
This page: a magnitude 4.3 earthquake was recorded 12 km (7 mi) west-southwest of Byron, CA, at 1:11 pm PDT on 16 July 2019 (20:11 UTC), 12 km deep. 10,938 people have reported feeling it to USGS.
USGS: 12km WSW of Byron, CA
13 km (8 mi) SSW of Brentwood, CA · 58 km (36 mi) N of San Jose, CA
- When
- 1:11 pm PDT on 16 July 2019 ()
- Where
- 12 km (7 mi) west-southwest of Byron, CA · earthquakes near Byron
- Magnitude
- M 4.3 (mw)
- Depth
- 12 km below the surface
- Felt
- 10,938 reports · strongest reported intensity IV
- Measured shaking
- intensity VI (ShakeMap)
- USGS impact alert
- green
- Nearest
- Contra Costa County, 20 km WNW
- Nearest mapped fault
- Greenville fault, 5 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 2324 days ago
Earthquake alerts for Byron, CA
Get a notification in this browser when USGS records an earthquake near Byron, 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 light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
At this magnitude and depth, people at rest would likely notice it out to about 121 km (75 mi) from the epicentre. In Byron, 12 km away, the estimate is intensity IV (light). 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: Brentwood 14 km, intensity IV · Livermore 15 km, intensity IV · Discovery Bay 17 km, intensity III · San Ramon 20 km, intensity III · Pleasanton 20 km, intensity III · Oakley 20 km, intensity III · Dublin 20 km, intensity III · Antioch 21 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 44 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 3,800× the energy of this one
- Mineral, Virginia 2011 M 5.8 170× the energy of this one
- Magna, Utah 2020 M 5.7 120× the energy of this one
- This earthquake M 4.3 about 44 tons of TNT
- Around the size people start to feel M 3.0 this one released 92× 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 1.3 times the energy of this one.
Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:
- 5.8 The 1980 Livermore, California Earthquake · 3 km NNW of this epicentre
- 5.7 15 km NE of East Foothills, California · 38 km S of this epicentre
- 5.5 6 km NNE of East Foothills, California · 43 km S of this epicentre
- 5.4 9 km NE of Livermore, California · 9 km SSE of this epicentre
- 5.3 6 km E of East Foothills, California · 47 km S 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 37.8187, -121.7568. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Contra Costa County, CA | 20 km (13 mi) | WNW | earthquakes near Contra Costa County |
| Alameda County, CA | 23 km (15 mi) | SW | earthquakes near Alameda County |
| San Joaquin County, CA | 44 km (28 mi) | ENE | earthquakes near San Joaquin County |
| Solano County, CA | 52 km (33 mi) | NNW | earthquakes near Solano County |
| Santa Clara County, CA | 67 km (41 mi) | S | earthquakes near Santa Clara County |
| San Mateo County, CA | 70 km (44 mi) | SW | earthquakes near San Mateo County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
57 earthquakes have been recorded within 50 km since this one.
- 1.6 4km NNE of Dublin, CA
- 2.2 4km N of Dublin, CA
- 2.8 4km N of Dublin, CA
- 1.8 4km NNE of Dublin, CA
- 1.6 4km NNE of Dublin, CA
- 2.6 4km NNE of Dublin, CA
- 1.6 3km SW of Clayton, CA
- 2.3 3km NE of Orinda, CA
- 1.6 4km N of Dublin, CA
- 1.6 4km NNE of Dublin, CA
- 1.6 4km NNE of Dublin, CA
- 2.0 4km N of Dublin, CA
- 1.9 4km N of Dublin, CA
- 1.8 4km NNE of Dublin, CA
- 1.7 4km N of Dublin, 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.