Earthquake · reviewed by a seismologist
M 1.9md
Earthquake near Diablo, CA
No earthquake was likely felt in Diablo in the 24 hours to 3:23 am PST (11:23 UTC). The last one was M 2.5, 18 km (11 mi) NNW, at 1:23 am PST on 2 November 2026, estimated intensity II (weak) in town; 39 felt reports to USGS. Every earthquake near Diablo
This page: a magnitude 1.9 earthquake was recorded 4 km (2 mi) north of Diablo, CA, at 9:13 pm PST on 28 February 2020 (05:13 UTC), 17 km deep. 2 people have reported feeling it to USGS.
USGS: 4km N of Diablo, CA
8 km (5 mi) ESE of Walnut Creek, CA · 42 km (26 mi) ENE of San Francisco, CA
- When
- 9:13 pm PST on 28 February 2020 ()
- Where
- 4 km (2 mi) north of Diablo, CA · earthquakes near Diablo
- Magnitude
- M 1.9 (md)
- Depth
- 17 km below the surface
- Felt
- 2 reports · strongest reported intensity I
- Nearest
- Contra Costa County, 6 km N
- Nearest mapped fault
- Calaveras fault, 7 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 2445 days ago
Earthquake alerts for Diablo, 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 it was probably too small to be felt, even directly above it. In Diablo, 4 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.
Earthquakes near other towns within 30 km: Danville, Alamo, Blackhawk, Clayton, Walnut Creek, San Ramon.
How big was it?
This earthquake released about 24 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 640,000× the energy of this one
- Magna, Utah 2020 M 5.7 450,000× the energy of this one
- Around the size people start to feel M 3.0 40× the energy of this one
- This earthquake M 1.9 about 24 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 6,200 times the energy of this one.
Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:
- 6.0 The 2014 South Napa, California Earthquake · 49 km NW of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 17 km E of this epicentre
- 5.7 15 km NE of East Foothills, California · 50 km SSE of this epicentre
- 5.4 South of Elmira, California · 48 km N of this epicentre
- 5.4 9 km NE of Livermore, California · 26 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 37.8697, -121.9597. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Contra Costa County, CA | 6 km (3 mi) | N | earthquakes near Contra Costa County |
| Alameda County, CA | 25 km (16 mi) | S | earthquakes near Alameda County |
| Solano County, CA | 44 km (27 mi) | N | earthquakes near Solano County |
| San Joaquin County, CA | 61 km (38 mi) | E | earthquakes near San Joaquin County |
| San Mateo County, CA | 62 km (39 mi) | SW | earthquakes near San Mateo County |
| Marin County, CA | 72 km (45 mi) | WNW | earthquakes near Marin 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.
- 2.0 2km NNW of Crockett, CA
- 1.6 1km SSE of San Ramon, CA
- 2.0 2km E of Berkeley, CA
- 2.6 2km E of Berkeley, CA
- 2.2 5km SSE of Newark, CA
- 1.9 1km WSW of Pittsburg, CA
- 1.7 1km S of Kensington, CA
- 2.0 1km W of Pleasant Hill, CA
- 2.3 12km ESE of Suisun City, CA
- 1.5 1km SSE of San Ramon, CA
- 1.9 1km S of San Ramon, CA
- 1.8 11km NNW of Pittsburg, CA
- 1.9 2km NE of Danville, CA
- 1.6 4km ESE of Fremont, CA
- 1.8 13km SSE of Livermore, 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.