Earthquake near Half Moon Bay, CA

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 Half Moon Bay, 10 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: El Granada, Moss Beach, Montara, Highlands-Baywood Park, Woodside, Emerald Lake Hills.

How big was it?

This earthquake released about 5.7 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.

1. Mineral, Virginia 2011 M 5.8 2,600,000× the energy of this one
2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
3. Around the size people start to feel M 3.0 170× the energy of this one
4. This earthquake M 1.5 about 5.7 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 7 earthquakes of M5 or more within 50 km; the five largest:

1. 7.9 The 1906 San Francisco, California Earthquake · 41 km N of this epicentre Apr 18, 1906
2. 5.8 7 km NNW of Boulder Creek, California · 37 km SE of this epicentre Sep 5, 1955
3. 5.5 Santa Cruz Mountains, California · 49 km ESE of this epicentre Nov 9, 1914
4. 5.5 1 km WNW of Davenport, California · 47 km SSE of this epicentre Oct 24, 1926
5. 5.3 The 1957 San Francisco, California Earthquake · 32 km N of this epicentre Mar 22, 1957

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 37.3817, -122.4825. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 2.1 5 km SSE of Portola Valley, CA 17:19 UTC
2. 2.1 6 km WNW of San Francisco Zoo, CA 16:30 UTC
3. 1.7 5 km WSW of Colma, CA 08:38 UTC
4. 1.5 4 km NNE of Lompico, CA 16:02 UTC
5. 2.1 1 km SSE of Los Altos Hills, CA 18:03 UTC
6. 2.5 2 km SSE of Los Altos Hills, CA 12:20 UTC
7. 1.6 4 km WSW of Colma, CA 01:55 UTC
8. 1.5 1 km N of Millbrae, CA 17:52 UTC
9. 1.9 2 km NNE of Millbrae, CA 12:56 UTC
10. 2.2 4 km WSW of Cupertino, CA 11:08 UTC
11. 2.2 6 km WNW of San Francisco Zoo, CA 21:05 UTC
12. 1.5 6 km WNW of San Francisco Zoo, CA 20:11 UTC
13. 2.1 3 km N of San Lorenzo, CA 05:52 UTC
14. 1.5 2 km ESE of Pacifica, CA 04:43 UTC
15. 1.7 2 km NNE of Saratoga, CA 17:18 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:07 UTC. 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.