Earthquake · reviewed by a seismologist
M 1.5md
Earthquake near Mammoth Lakes, CA
No earthquake was likely felt in Mammoth Lakes in the 24 hours to 4:23 am PST (12:23 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 1.5 earthquake was recorded 29 km (18 mi) south-southeast of Mammoth Lakes, CA, at 10:43 pm PDT on 16 September 2021 (05:43 UTC), 4.2 km deep.
USGS: 27km W of Round Valley, CA
- When
- 10:43 pm PDT on 16 September 2021 ()
- Where
- 29 km (18 mi) south-southeast of Mammoth Lakes, CA · earthquakes near Mammoth Lakes
- Magnitude
- M 1.5 (md)
- Depth
- 4.2 km below the surface
- Felt
- no reports yet
- Nearest
- Mono County, 58 km N
- Nearest mapped fault
- Hilton Creek fault, 17 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 1882 days ago
Earthquake alerts for Mammoth Lakes, CA
Get a notification in this browser when USGS records an earthquake near Mammoth Lakes, CA. No account or email needed.
Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 9 km (6 mi) from the epicentre. In Mammoth Lakes, 29 km away, the estimate is intensity I (not felt). 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 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
- Around the size people start to feel M 3.0 160× the energy of this one
- This earthquake M 1.5 about 5.9 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 4.8 on 2016-02-16 — about 72,000 times the energy of this one.
Before 2016, the USGS record lists 36 earthquakes of M5 or more within 50 km; the five largest:
- 6.4 The 1986 Chalfant Valley, California Earthquake · 43 km ENE of this epicentre
- 6.2 9 km SW of Aspen Springs, California · 14 km NE of this epicentre
- 6.1 11 km WNW of Aspen Springs, California · 22 km NNE of this epicentre
- 6.1 8 km W of Aspen Springs, California · 19 km NNE of this epicentre
- 6.1 4 km NNW of Round Valley, California · 27 km ENE 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 37.3967, -118.8977. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Mono County, CA | 58 km (36 mi) | N | earthquakes near Mono County |
| Madera County, CA | 78 km (49 mi) | WSW | earthquakes near Madera County |
| Mariposa County, CA | 92 km (57 mi) | WNW | earthquakes near Mariposa County |
| Fresno County, CA | 98 km (61 mi) | SW | earthquakes near Fresno County |
| Tuolumne County, CA | 117 km (73 mi) | NW | earthquakes near Tuolumne County |
| Esmeralda County, NV | 119 km (74 mi) | ENE | earthquakes near Esmeralda County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 1.7 18km WSW of Toms Place, CA
- 2.1 17km WSW of Toms Place, CA
- 2.8 17km WSW of Toms Place, CA
- 1.9 18km WSW of Toms Place, CA
- 2.7 17km WSW of Toms Place, CA
- 3.0 17km WSW of Toms Place, CA
- 3.0 17km WSW of Toms Place, CA
- 1.5 1km SSE of Dixon Lane-Meadow Creek, CA
- 1.6 14km WNW of Toms Place, CA
- 1.8 18km WSW of Toms Place, CA
- 2.4 17km WSW of Toms Place, CA
- 1.5 2km E of Bishop, CA
- 3.1 1km ENE of Bishop, CA
- 2.7 2km E of Bishop, CA
- 1.6 32km NE of North Fork, 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
- 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.