QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mw

Earthquake near Mammoth Lakes, CA

No earthquake was likely felt in Mammoth Lakes in the 24 hours to 1:49 pm PST (21:49 UTC). The last one was M 2.9, 26 km (16 mi) SSE, at 3:54 am PDT on 24 October 2026, estimated intensity II (weak) in town. Every earthquake near Mammoth Lakes

This page: a magnitude 3.8 earthquake was recorded 18 km (11 mi) southeast of Mammoth Lakes, CA, at 2:19 pm PST on 8 December 2017 (22:19 UTC), 2.8 km deep. 24 people have reported feeling it to USGS.

USGS: 12km W of Toms Place, CA

2:19 pm PST, Dec 8, 2017 · · 2.8 km deep · released about 7.1 tons of TNT

10 km30 km60 km120 km N Mono County 41 kmMadera County 91 kmMariposa County 97 kmEsmeralda County 107 kmMineral County 113 kmTuolumne County 114 kmFresno County 115 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
2:19 pm PST on 8 December 2017 ()
Where
18 km (11 mi) southeast of Mammoth Lakes, CA · earthquakes near Mammoth Lakes
Magnitude
M 3.8 (mw)
Depth
2.8 km below the surface
Felt
24 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
USGS impact alert
green
Nearest
Mono County, 41 km N
Nearest mapped fault
Hilton Creek fault, 3 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 3056 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 81 km (50 mi) from the epicentre. In Mammoth Lakes, 18 km away, the estimate is intensity III (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: Mammoth Lakes 18 km, intensity III · West Bishop 38 km, intensity III · Dixon Lane-Meadow Creek 39 km, intensity II · Bishop 42 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 7.1 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 24,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,100× the energy of this one
  3. Magna, Utah 2020 M 5.7 760× the energy of this one
  4. This earthquake M 3.8 about 7.1 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 15× more

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 39 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.4 The 1986 Chalfant Valley, California Earthquake · 32 km E of this epicentre
  2. 6.2 9 km SW of Aspen Springs, California · 5 km S of this epicentre
  3. 6.1 11 km WNW of Aspen Springs, California · 5 km NNW of this epicentre
  4. 6.1 8 km W of Aspen Springs, California · 1 km NNE of this epicentre
  5. 6.1 4 km NNW of Round Valley, California · 20 km ESE 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 37.5473, -118.8103. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mono County, CA 41 km (26 mi) N earthquakes near Mono County
Madera County, CA 91 km (57 mi) WSW earthquakes near Madera County
Mariposa County, CA 97 km (60 mi) W earthquakes near Mariposa County
Esmeralda County, NV 107 km (66 mi) ENE earthquakes near Esmeralda County
Mineral County, NV 113 km (70 mi) NNE earthquakes near Mineral County
Tuolumne County, CA 114 km (71 mi) WNW earthquakes near Tuolumne County

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

Aftershocks so far

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

  1. 3.1 16km WSW of Toms Place, CA
  2. 2.2 11km W of Toms Place, CA
  3. 1.6 14km W of Toms Place, CA
  4. 2.5 17km ENE of Toms Place, CA
  5. 1.7 7km ENE of Mammoth Lakes, CA
  6. 1.6 5km NW of Round Valley, CA
  7. 2.0 13km WNW of Toms Place, CA
  8. 1.6 16km WSW of Toms Place, CA
  9. 2.1 11km W of Toms Place, CA
  10. 1.8 14km ESE of Mammoth Lakes, CA
  11. 1.6 14km W of Toms Place, CA
  12. 1.7 6km E of Mammoth Lakes, CA
  13. 2.1 5km E of Mammoth Lakes, CA
  14. 2.0 6km E of Mammoth Lakes, CA
  15. 1.6 14km W of Toms Place, 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.