0km E of Point Arena, CA

2021-07-09 05:24 UTC · 8.0 km deep · released about 7.3 lb of TNT

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: 2021-07-09 05:24 UTC
Magnitude: M 1.6 (md)
Depth: 8.0 km below the surface
Felt: no reports yet
Nearest: Mendocino County, 62 km NNE
Status: Reviewed by a seismologist

USGS · last changed by USGS 1904 days ago · we first saw it 1904 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 7.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
Around the size people start to feel M 3.0 130× the energy of this one
This earthquake M 1.6 about 7.3 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.

Where

Map loads when it scrolls into view

Epicentre 38.9132, -123.6933. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
Mendocino County, CA	62 km (38 mi)	SSW of here	earthquakes near Mendocino County
Sonoma County, CA	79 km (49 mi)	WNW of here	earthquakes near Sonoma County
Lake County, CA	85 km (53 mi)	WSW of here	earthquakes near Lake County
Marin County, CA	126 km (79 mi)	NW of here	earthquakes near Marin County
Napa County, CA	127 km (79 mi)	WNW of here	earthquakes near Napa County
Glenn County, CA	135 km (84 mi)	SW of here	earthquakes near Glenn County

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

Aftershocks so far

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

1.9 18km SW of Willits, CA 08:57 UTC
1.6 7km NE of Mendocino, CA 11:21 UTC
1.8 12km ENE of Navarro Head, CA 18:23 UTC
2.0 18km SW of Willits, CA 11:10 UTC
1.8 20km ENE of Navarro Head, CA 04:57 UTC
1.9 18km SW of Willits, CA 18:19 UTC
1.6 16km ESE of Boonville, CA 14:19 UTC
1.7 20km ESE of Navarro Head, CA 20:41 UTC
1.5 9km S of Boonville, CA 21:46 UTC
1.5 16km E of Mendocino, CA 00:34 UTC
2.0 20km ESE of Navarro Head, CA 02:39 UTC
1.5 14km E of Boonville, CA 10:08 UTC
1.8 5km NW of Point Arena, CA 19:57 UTC
1.8 16km W of Ukiah, CA 15:26 UTC
1.6 16km ESE of Boonville, CA 20:59 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 14:54 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.