Earthquake · reviewed by a seismologist
M 1.5md
Earthquake near Alamo, CA
No earthquake was likely felt in Alamo in the 24 hours to 8:14 am PST (16:14 UTC). The last one was M 2.1, 11 km (7 mi) NNW, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Alamo
This page: a magnitude 1.5 earthquake was recorded 3 km (2 mi) northeast of Alamo, CA, at 11:03 am PDT on 16 August 2019 (18:03 UTC), 7.8 km deep.
USGS: 3km NE of Alamo, CA
5 km (3 mi) SSE of Walnut Creek, CA · 37 km (23 mi) ENE of San Francisco, CA
- When
- 11:03 am PDT on 16 August 2019 ()
- Where
- 3 km (2 mi) northeast of Alamo, CA · earthquakes near Alamo
- Magnitude
- M 1.5 (md)
- Depth
- 7.8 km below the surface
- Felt
- no reports yet
- Nearest
- Contra Costa County, 8 km NE
- Nearest mapped fault
- Calaveras fault, 4 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 2642 days ago
Earthquake alerts for Alamo, 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 6 km (4 mi) from the epicentre. In Alamo, 3 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: Alamo 3 km, intensity II · Danville 5 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
- Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
- Around the size people start to feel M 3.0 180× the energy of this one
- This earthquake M 1.5 about 5.4 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 4.4 on 2018-01-04 — about 21,000 times the energy of this one.
Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:
- 7.9 The 1906 San Francisco, California Earthquake · 49 km WSW of this epicentre
- 6.0 The 2014 South Napa, California Earthquake · 47 km NW of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 21 km E of this epicentre
- 5.4 South of Elmira, California · 49 km N of this epicentre
- 5.4 9 km NE of Livermore, California · 29 km ESE 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 37.8642, -122.0080. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Contra Costa County, CA | 8 km (5 mi) | NE | earthquakes near Contra Costa County |
| Alameda County, CA | 26 km (16 mi) | SSE | earthquakes near Alameda County |
| Solano County, CA | 45 km (28 mi) | N | earthquakes near Solano County |
| San Mateo County, CA | 59 km (37 mi) | SSW | earthquakes near San Mateo County |
| San Joaquin County, CA | 65 km (40 mi) | E | earthquakes near San Joaquin County |
| Marin County, CA | 68 km (42 mi) | WNW | earthquakes near Marin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.7 1km SW of Pleasant Hill, CA
- 2.1 0km W of Pleasant Hill, CA
- 4.5 1km SSE of Pleasant Hill, CA
- 2.5 1km S of Pleasant Hill, CA
- 1.7 1km SSW of Pleasant Hill, CA
- 1.9 4km SSW of Vallejo, CA
- 2.0 9km ENE of Milpitas, CA
- 3.5 5km WSW of Colma, CA
- 1.6 4km NNE of Dublin, CA
- 1.7 4km NNE of Dublin, CA
- 1.6 4km NNE of Dublin, CA
- 1.6 4km N of Dublin, CA
- 1.6 4km NNE of Dublin, CA
- 2.2 4km N of Dublin, CA
- 2.8 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.