Earthquake near Ronan, MT

USGS: 11 km W of Ronan, Montana

2:26 pm MDT, Oct 21, 2019 · 2019-10-21 20:26 UTC · 8.6 km deep · released about 14 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: 2:26 pm MDT on 21 October 2019 (2019-10-21 20:26 UTC)
Where: 11 km (7 mi) W of Ronan, MT · earthquakes near Ronan
Magnitude: M 1.8 (ml)
Depth: 8.6 km below the surface
Felt: no reports yet
Nearest: Lake County, 18 km NE
Nearest mapped fault: Mission fault, 17 km from its surface trace — near is not the same as on
Status: Reviewed by a seismologist

USGS · last changed by USGS 2538 days ago · we first saw it 2538 days ago

A magnitude 1.8 earthquake was recorded 11 km (7 mi) W of Ronan, MT, at 2:26 pm MDT on 21 October 2019 (20:26 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Pablo, Polson.

How big was it?

This earthquake released about 14 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.

Mineral, Virginia 2011 M 5.8 1,100,000× the energy of this one
Magna, Utah 2020 M 5.7 760,000× the energy of this one
Around the size people start to feel M 3.0 68× the energy of this one
This earthquake M 1.8 about 14 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 since 1900 lists no earthquake of M5 or more within 50 km.

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 47.5292, -114.2497. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction from the epicentre
Lake County, MT	18 km (11 mi)	NE	earthquakes near Lake County
Missoula County, MT	62 km (39 mi)	SSE	earthquakes near Missoula County
Sanders County, MT	74 km (46 mi)	WNW	earthquakes near Sanders County
Mineral County, MT	77 km (48 mi)	SW	earthquakes near Mineral County
Flathead County, MT	86 km (54 mi)	N	earthquakes near Flathead County
Powell County, MT	125 km (78 mi)	SE	earthquakes near Powell County

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

Aftershocks so far

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

3.0 17 km SSE of Swan Lake, Montana 03:19 UTC
1.6 9 km ENE of Ronan, Montana 03:28 UTC
1.5 6 km SW of Condon, Montana 03:49 UTC
1.6 4 km W of Ravalli, Montana 03:04 UTC
1.6 4 km NW of Niarada, Montana 17:27 UTC
2.1 18 km SSE of Swan Lake, Montana 23:29 UTC
1.8 17 km SSW of Condon, Montana 00:23 UTC
1.9 17 km SSW of Condon, Montana 01:14 UTC
1.5 11 km ENE of Ronan, Montana 19:06 UTC
2.0 8 km S of Condon, Montana 14:30 UTC
1.6 Western Montana 08:39 UTC
1.9 21 km NNW of Condon, Montana 11:35 UTC
2.5 18 km WNW of Dixon, Montana 06:44 UTC
3.7 3 km NE of Ravalli, Montana 13:47 UTC
1.5 Western Montana 23:31 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:50 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.