M1.7 earthquake 5 km SSW of Piñon Hills, California, United States
A magnitude 1.7 earthquake struck 5 km SSW of Piñon Hills, California, United States at 18:36 local time (01:36 UTC) on 22 Oct 2026, at a depth of 10 km, according to USGS.
revised from M1.8
Data: USGS · updated 2026-10-23 21:39 UTC · reviewed
- Magnitude
- 1.7micro
local magnitude (Richter) (ml)
revised from 1.8 - Depth
- 9.9 km
- Status
- Reviewed
- Origin time
- 2026-10-23 01:36:18 UTC
- Local: 22 Oct 2026, 18:36:18 (America/Los Angeles)
- Epicentre
- 34.386° N, 117.676° W
Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map
Nearby places
| Place | Distance | Est. shaking |
|---|---|---|
| Piñon HillsCalifornia, United States · pop. 7,272 | 5 km | INot felt |
| PhelanCalifornia, United States · pop. 14,304 | 11 km | INot felt |
| Rancho CucamongaCalifornia, United States · pop. 175,236 | 32 km | INot felt |
| UplandCalifornia, United States · pop. 76,443 | 32 km | INot felt |
| ClaremontCalifornia, United States · pop. 36,283 | 32 km | INot felt |
| AdelantoCalifornia, United States · pop. 33,166 | 33 km | INot felt |
| RiversideCalifornia, United States · pop. 317,261 | 55 km | INot felt |
| Los AngelesCalifornia, United States · pop. 3,820,914 | 64 km | INot felt |
Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more.
Every agency's solution
Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · CI, which has been reviewed by an analyst.
| Agency | Magnitude | Depth | Epicentre | Time offset | Status |
|---|---|---|---|---|---|
| USGS · CIheadlineSouthern California Seismic Network via U.S. Geological Survey | 1.7 mlwas 1.8 | 9.9 km | 34.39° N, 117.68° W | – | Reviewed · 2 revisions |
How big was it?
Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.
It released roughly the energy of 5 kg of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 10 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M1.7 releases about 11× the energy of M1.0, and its waves are about 4.9× taller on a seismogram. Energy: 5 kg of TNT vs 477 g of TNT.
Each square is the energy of one M1.0. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
14 later earthquakes within 30 km; the largest was M1.2 11 days ago. 4 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M1.7
14 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 31.07 | 0.9 | 5 |
| 49.04 | 0.7 | 8 |
| 73.87 | 1.0 | 12 |
| 192.16 | 0.9 | 4 |
| 192.37 | 1.1 | 4 |
| 237.50 | 1.2 | 12 |
| 239.95 | 1.1 | 9 |
| 327.27 | 0.9 | 6 |
| 337.16 | 0.9 | 14 |
| 337.16 | 0.4 | 13 |
| 349.44 | 0.9 | 7 |
| 388.96 | 0.8 | 11 |
| 437.49 | 1.1 | 13 |
| 482.99 | 1.1 | 10 |
- 1.26 km NNW of Glendora, California, United States11-01 23:06
- 1.111 km NW of Muscoy, California, United States11-10 07:05
- 1.110 km N of Rancho Cucamonga, California, United States10-31 01:58
- 1.113 km NE of Rancho Cucamonga, California, United States11-02 01:33
- 1.114 km WNW of Muscoy, California, United States11-12 04:35
- 1.014 km NNW of Fontana, California, United States10-26 03:28
- 0.94 km SW of Piñon Hills, California, United States11-05 16:52
- 0.95 km SW of Piñon Hills, California, United States10-24 08:40
- 0.916 km NNE of Rancho Cucamonga, California, United States11-06 02:45
- 0.99 km N of Rancho Cucamonga, California, United States10-31 01:46
- 0.913 km NW of Muscoy, California, United States11-06 15:02
- 0.89 km NNW of Glendora, California, United States11-08 06:33
- 0.714 km NNE of Rancho Cucamonga, California, United States10-25 02:38
- 0.416 km N of Rancho Cucamonga, California, United States11-06 02:46
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports close 14 days after an earthquake.
Reports on SeismoAtlas
No reports yet.
Event id ci41350839. First recorded here 23 Oct 2026, 01:39:20 UTC. Solutions: USGS · CI (usgs:ci41350839). Cite as: SeismoAtlas, “M1.7 earthquake 5 km SSW of Piñon Hills, California, United States”, https://seismoatlas.com/earthquake/ci41350839-m1-7-earthquake-5-km-ssw-of-pinon-hills-california-united-states, data from USGS.
JSON: /api/v1/events/ci41350839. SeismoAtlas is not an official warning service.