QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Yosemite Valley, CA

No earthquake was likely felt in Yosemite Valley in the 24 hours to 2:44 pm PST (22:44 UTC). The last one was M 2.5, 22 km (14 mi) SE, at 7:51 am PDT on 28 August 2026, estimated intensity II (weak) in town. Every earthquake near Yosemite Valley

This page: a magnitude 1.7 earthquake was recorded 22 km (14 mi) east-southeast of Yosemite Valley, CA, at 10:01 pm PST on 27 December 2020 (06:01 UTC), 13 km deep.

USGS: 22km ESE of Yosemite Valley, CA

10:01 pm PST, Dec 27, 2020 · · 13 km deep · released about 9.3 lb of TNT

10 km30 km60 km120 km N Mariposa County 49 kmMono County 53 kmMadera County 59 kmTuolumne County 68 kmFresno County 101 kmAlpine 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
10:01 pm PST on 27 December 2020 ()
Where
22 km (14 mi) east-southeast of Yosemite Valley, CA · earthquakes near Yosemite Valley
Magnitude
M 1.7 (md)
Depth
13 km below the surface
Felt
no reports yet
Nearest
Mariposa County, 49 km W
Nearest mapped fault
Silver Lake fault, 25 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 2138 days ago

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 Yosemite Valley, 22 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.

How big was it?

This earthquake released about 9.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 100× the energy of this one
  4. This earthquake M 1.7 about 9.3 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.

For this area

The largest earthquake within 50 km since 2016 was M 4.4 on 2020-02-01 — about 13,000 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.1 11 km WNW of Aspen Springs, California · 47 km E of this epicentre
  2. 6.1 8 km W of Aspen Springs, California · 50 km E of this epicentre
  3. 6.0 7 km ENE of Mammoth Lakes, California · 41 km E of this epicentre
  4. 5.9 8 km NNE of Mammoth Lakes, California · 39 km ENE of this epicentre
  5. 5.9 11 km SE of Mammoth Lakes, California · 44 km E 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 37.6425, -119.3627. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Mariposa County, CA 49 km (30 mi) W earthquakes near Mariposa County
Mono County, CA 53 km (33 mi) NE earthquakes near Mono County
Madera County, CA 59 km (37 mi) SW earthquakes near Madera County
Tuolumne County, CA 68 km (42 mi) NW earthquakes near Tuolumne County
Fresno County, CA 101 km (63 mi) SSW earthquakes near Fresno County
Alpine County, CA 115 km (72 mi) NNW earthquakes near Alpine County

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 13km W of Toms Place, CA
  2. 1.5 17km SW of Toms Place, CA
  3. 2.7 17km SW of Toms Place, CA
  4. 1.9 14km SE of Mammoth Lakes, CA
  5. 1.6 22km ESE of Yosemite Valley, CA
  6. 1.6 8km ESE of Mammoth Lakes, CA
  7. 2.3 8km ESE of Mammoth Lakes, CA
  8. 1.9 9km E of Mammoth Lakes, CA
  9. 1.6 21km SE of Yosemite Valley, CA
  10. 1.7 12km ESE of Mammoth Lakes, CA
  11. 2.9 14km S of Mammoth Lakes, CA
  12. 1.9 17km WSW of Toms Place, CA
  13. 1.8 26km NE of Oakhurst, CA
  14. 2.5 15km WSW of Toms Place, CA
  15. 2.3 13km 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.