Earthquake near Alturas, CA

USGS: 13km SE of Likely, CA

3:30 pm PST, Dec 18, 2017 · 2017-12-18 23:30 UTC · 7.7 km deep · released about 420 lb of TNT

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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: 3:30 pm PST on 18 December 2017 (2017-12-18 23:30 UTC)
Where: 40 km (25 mi) SSE of Alturas, CA · earthquakes near Alturas
Magnitude: M 2.8 (md)
Depth: 7.7 km below the surface
Felt: no reports yet
Nearest: Lassen County, 51 km SSW
Status: Reviewed by a seismologist

USGS · last changed by USGS 3014 days ago · we first saw it 3014 days ago

A magnitude 2.8 earthquake was recorded 40 km (25 mi) SSE of Alturas, CA, at 3:30 pm PST on 18 December 2017 (23:30 UTC). This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 420 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 36,000× the energy of this one
Magna, Utah 2020 M 5.7 26,000× the energy of this one
Around the size people start to feel M 3.0 2.3× the energy of this one
This earthquake M 2.8 about 420 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 2 earthquakes of M5 or more within 50 km:

5.2 12 km SE of Eagleville, California · 35 km ENE of this epicentre Jun 18, 1937
5.0 26 km S of Likely, California · 17 km SSW of this epicentre Nov 27, 1976

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

Map loads when it scrolls into view

Epicentre 41.1435, -120.3960. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction from the epicentre
Lassen County, CA	51 km (32 mi)	SSW	earthquakes near Lassen County
Modoc County, CA	57 km (35 mi)	NNW	earthquakes near Modoc County
Washoe County, NV	77 km (48 mi)	SE	earthquakes near Washoe County

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

Aftershocks so far

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

1.6 11 km E of Eagleville, California 23:32 UTC
2.4 46 km S of Eagleville, California 02:37 UTC
1.9 23 km SSE of Eagleville, California 02:41 UTC
2.1 12 km SW of Lake City, California 19:25 UTC
1.6 14 km SE of Eagleville, California 08:32 UTC
1.6 24 km SE of Likely, California 10:25 UTC
2.6 18 km SW of Reederville, NV 23:07 UTC
2.1 13 km SE of Alturas, California 17:33 UTC
2.2 6km ESE of Likely, CA 01:52 UTC
2.5 22km W of Reederville, NV 00:18 UTC
2.3 20km W of Reederville, NV 01:46 UTC
2.4 5km E of Likely, CA 14:13 UTC
1.7 16 km SW of Eagleville, California 00:59 UTC
2.4 25km WSW of Reederville, NV 11:49 UTC
2.1 11km W of Likely, CA 20:27 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:08 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.