QuakeIndex

explosion · reviewed by a seismologist

M 1.7md

Earthquake near El Granada, CA

No earthquake was likely felt in El Granada in the 24 hours to 11:46 pm PST (07:46 UTC). The last one was M 2.7, 14 km (9 mi) N, at 5:17 pm PDT on 28 October 2026, estimated intensity II (weak) in town; 526 felt reports to USGS. Every earthquake near El Granada

No: USGS classifies this as a explosion, not an earthquake. A magnitude 1.7 explosion was recorded 5 km (3 mi) east-northeast of El Granada, CA, at 5:12 pm PDT on 17 September 2024 (00:12 UTC), less than 1 km deep.

USGS: 5 km ENE of El Granada, CA

29 km (18 mi) S of San Francisco, CA · 11 km (7 mi) WSW of San Mateo, CA

5:12 pm PDT, Sep 17, 2024 · · -0.1 km deep · released about 9.6 lb of TNT

Every earthquake near El Granada Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 12 kmAlameda County 47 kmSan Francisco County 59 kmContra Costa County 61 kmMarin County 66 kmSanta Cruz County 67 kmSanta Clara County 72 kmSolano County 93 kmNapa County 110 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
5:12 pm PDT on 17 September 2024 ()
Where
5 km (3 mi) east-northeast of El Granada, CA · earthquakes near El Granada
Magnitude
M 1.7 (md)
Depth
-0.1 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 12 km SSE
Nearest mapped fault
San Andreas 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 772 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 12 km (7 mi) from the epicentre. In El Granada, 5 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: Half Moon Bay 6 km, intensity II · Burlingame 9 km, intensity II · Millbrae 9 km, intensity II · San Mateo 10 km, intensity II · Pacifica 12 km, intensity II. Estimated for each town centre; each link is that town's own record.

USGS catalogues this as explosion, not an earthquake.

How big was it?

This earthquake released about 9.6 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 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 99× the energy of this one
  4. This earthquake M 1.7 about 9.6 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 12,000 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 7.9 The 1906 San Francisco, California Earthquake · 28 km NNW of this epicentre
  2. 5.8 7 km NNW of Boulder Creek, California · 44 km SSE of this epicentre
  3. 5.3 The 1957 San Francisco, California Earthquake · 17 km NNW of this epicentre
  4. 5.1 7 km SW of Monte Sereno, California · 49 km SE 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 37.5195, -122.4190. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Mateo County, CA 12 km (8 mi) SSE earthquakes near San Mateo County
Alameda County, CA 47 km (29 mi) ENE earthquakes near Alameda County
San Francisco County, CA 59 km (36 mi) WNW earthquakes near San Francisco County
Contra Costa County, CA 61 km (38 mi) NE earthquakes near Contra Costa County
Marin County, CA 66 km (41 mi) NNW earthquakes near Marin County
Santa Cruz County, CA 67 km (42 mi) SSE earthquakes near Santa Cruz County

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

Aftershocks so far

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

  1. 2.2 5 km WSW of San Francisco Zoo, CA
  2. 1.5 5 km WSW of San Francisco Zoo, CA
  3. 1.6 5 km WSW of San Francisco Zoo, CA
  4. 2.2 5 km WSW of San Francisco Zoo, CA
  5. 2.4 5 km WSW of San Francisco Zoo, CA
  6. 1.9 5 km NW of San Francisco Zoo, CA
  7. 1.5 6 km NW of San Francisco Zoo, CA
  8. 1.6 6 km NW of San Francisco Zoo, CA
  9. 2.9 5 km NW of San Francisco Zoo, CA
  10. 2.5 5 km NW of San Francisco Zoo, CA
  11. 2.1 5 km NW of San Francisco Zoo, CA
  12. 3.5 5 km NW of San Francisco Zoo, CA
  13. 1.7 6 km WSW of Daly City, CA
  14. 2.1 2 km NW of Castro Valley, CA
  15. 1.5 10 km 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.