QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Redwood City, CA

No earthquake was likely felt in Redwood City in the 24 hours to 6:46 pm PST (02:46 UTC). The last one was M 1.9, 5 km (3 mi) S, at 4:14 pm PDT on 11 October 2026, estimated intensity II (weak) in town; 1 felt report to USGS. Every earthquake near Redwood City

This page: a magnitude 1.8 earthquake was recorded 48 km (30 mi) south-southwest of Redwood City, CA, at 11:38 pm PDT on 10 August 2019 (06:38 UTC), 7.8 km deep.

USGS: 32km WNW of Bonny Doon, CA

64 km (40 mi) WSW of San Jose, CA · 44 km (27 mi) WNW of Santa Cruz, CA

11:38 pm PDT, Aug 10, 2019 · · 7.8 km deep · released about 15 lb of TNT

Every earthquake near Redwood City Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 35 kmSanta Cruz County 45 kmSanta Clara County 73 kmAlameda County 79 kmSan Francisco County 83 kmContra Costa County 102 kmMarin County 106 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
11:38 pm PDT on 10 August 2019 ()
Where
48 km (30 mi) south-southwest of Redwood City, CA · earthquakes near Redwood City
Magnitude
M 1.8 (md)
Depth
7.8 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 35 km NNE
Nearest mapped fault
San Gregorio fault, 14 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 2648 days ago

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 11 km (7 mi) from the epicentre. In Redwood City, 48 km away, the estimate is intensity I (not felt). 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.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 730,000× the energy of this one
  3. Around the size people start to feel M 3.0 65× the energy of this one
  4. This earthquake M 1.8 about 15 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.3 22 km S of Davenport, California · 43 km SE of this epicentre
  2. 6.3 16 km SW of Davenport, California · 25 km SE of this epicentre
  3. 5.8 7 km NNW of Boulder Creek, California · 33 km ENE of this epicentre
  4. 5.7 Monterey Bay area, California · 50 km SE of this epicentre
  5. 5.5 Santa Cruz Mountains, California · 45 km E 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 37.1135, -122.5017. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Mateo County, CA 35 km (22 mi) NNE earthquakes near San Mateo County
Santa Cruz County, CA 45 km (28 mi) ESE earthquakes near Santa Cruz County
Santa Clara County, CA 73 km (45 mi) E earthquakes near Santa Clara County
Alameda County, CA 79 km (49 mi) NE earthquakes near Alameda County
San Francisco County, CA 83 km (51 mi) NW earthquakes near San Francisco County
Contra Costa County, CA 102 km (63 mi) NNE earthquakes near Contra Costa 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. 1.6 11km WSW of Saratoga, CA
  2. 1.6 7km SW of Los Altos Hills, CA
  3. 1.7 11km W of Bonny Doon, CA
  4. 1.5 5km WSW of Lexington Hills, CA
  5. 2.2 12km WSW of Saratoga, CA
  6. 1.9 3km S of Los Altos Hills, CA
  7. 2.2 2km S of Los Altos Hills, CA
  8. 1.7 3km S of Los Altos Hills, CA
  9. 2.1 2km SSW of Los Altos Hills, CA
  10. 2.8 3km S of Los Altos Hills, CA
  11. 1.8 2km S of Los Altos Hills, CA
  12. 1.6 3km ESE of Highlands-Baywood Park, CA
  13. 1.6 15km S of Half Moon Bay, CA
  14. 1.8 8km SSW of Loyola, CA
  15. 2.7 7km N of Boulder Creek, 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.