QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Newark, CA

No earthquake was likely felt in Newark in the 24 hours to 12:11 am PST (08:11 UTC). The last one was M 3.5, 53 km (33 mi) ESE, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Newark

This page: a magnitude 1.7 earthquake was recorded 7 km (5 mi) west of Newark, CA, at 12:22 pm PDT on 26 April 2021 (19:22 UTC), 14 km deep.

USGS: 7km W of Newark, CA

8 km (5 mi) ENE of Redwood City, CA · 38 km (24 mi) NW of San Jose, CA

12:22 pm PDT, Apr 26, 2021 · · 14 km deep · released about 12 lb of TNT

10 km30 km60 km120 km N Alameda County 22 kmSan Mateo County 26 kmContra Costa County 45 kmSanta Clara County 52 kmSanta Cruz County 59 kmMarin County 79 kmSan Francisco County 83 kmSolano County 83 kmSan Joaquin County 87 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
12:22 pm PDT on 26 April 2021 ()
Where
7 km (5 mi) west of Newark, CA · earthquakes near Newark
Magnitude
M 1.7 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
Alameda County, 22 km NE
Nearest mapped fault
Hayward fault, 13 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 2016 days ago

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 Newark, 7 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: East Palo Alto, Menlo Park, Atherton, Palo Alto, Redwood City, Union City.

How big was it?

This earthquake released about 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 870,000× the energy of this one
  3. Around the size people start to feel M 3.0 78× the energy of this one
  4. This earthquake M 1.7 about 12 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 12,000 times the energy of this one.

Before 2016, the USGS record lists 17 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 45 km WNW of this epicentre
  2. 6.2 Near San Jose, California · 39 km SE of this epicentre
  3. 6.2 The 1984 Morgan Hill, California Earthquake · 47 km ESE of this epicentre
  4. 6.1 Near San Jose, California · 47 km SE of this epicentre
  5. 5.8 7 km NNW of Boulder Creek, California · 38 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 37.5343, -122.1238. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 22 km (14 mi) NE earthquakes near Alameda County
San Mateo County, CA 26 km (16 mi) WSW earthquakes near San Mateo County
Contra Costa County, CA 45 km (28 mi) NNE earthquakes near Contra Costa County
Santa Clara County, CA 52 km (32 mi) SE earthquakes near Santa Clara County
Santa Cruz County, CA 59 km (37 mi) S earthquakes near Santa Cruz County
Marin County, CA 79 km (49 mi) NW earthquakes near Marin County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

55 earthquakes have been recorded within 50 km since this one.

  1. 1.7 19km SE of Livermore, CA
  2. 2.0 9km NE of Milpitas, CA
  3. 1.7 3km WNW of Castro Valley, CA
  4. 1.7 9km N of Boulder Creek, CA
  5. 2.7 6km SSW of San Ramon, CA
  6. 3.9 3km N of San Lorenzo, CA
  7. 1.7 15km E of Seven Trees, CA
  8. 2.0 3km NE of Portola Valley, CA
  9. 2.5 20km SE of Livermore, CA
  10. 2.8 20km SE of Livermore, CA
  11. 1.8 2km ESE of Berkeley, CA
  12. 1.8 6km E of Fremont, CA
  13. 2.6 2km ENE of Hayward, CA
  14. 2.4 15km E of Seven Trees, CA
  15. 1.9 12km NE of Milpitas, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.