M0.5 earthquake 6 km N of Altadena, California, United States
A magnitude 0.5 earthquake struck 6 km N of Altadena, California, United States at 04:55 local time (11:55 UTC) on 31 Oct 2026, at a depth of 7 km, according to USGS.
revised from M0.9
Data: USGS · updated 2026-10-31 23:01 UTC · reviewed
- Magnitude
- 0.5micro
local magnitude (Richter) (ml)
revised from 0.9 - Depth
- 6.9 km
- Status
- Reviewed
- Origin time
- 2026-10-31 11:55:58 UTC
- Local: 31 Oct 2026, 04:55:58 (America/Los Angeles)
- Epicentre
- 34.239° N, 118.125° 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 |
|---|---|---|
| AltadenaCalifornia, United States · pop. 42,777 | 6 km | INot felt |
| La Cañada FlintridgeCalifornia, United States · pop. 20,246 | 7 km | INot felt |
| PasadenaCalifornia, United States · pop. 142,250 | 10 km | INot felt |
| South PasadenaCalifornia, United States · pop. 26,151 | 13 km | INot felt |
| Los AngelesCalifornia, United States · pop. 3,820,914 | 24 km | INot felt |
| AnaheimCalifornia, United States · pop. 350,742 | 49 km | INot felt |
| Long BeachCalifornia, United States · pop. 474,140 | 53 km | INot felt |
| Santa AnaCalifornia, United States · pop. 310,227 | 59 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 | 0.5 mlwas 0.9 | 6.9 km | 34.24° N, 118.12° W | – | Reviewed · 1 revision |
How big was it?
Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.
It released roughly the energy of 85 g 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 7 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M1.0 releases about 5.6× the energy of M0.5, and its waves are about 3.2× taller on a seismogram. Energy: 477 g of TNT vs 85 g of TNT.
Each square is the energy of one M0.5. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
6 later earthquakes within 30 km; the largest was M1.4 2 h 48 min ago. 11 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M0.5
6 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 35.17 | 1.2 | 12 |
| 104.52 | 1.1 | -1 |
| 141.55 | 0.5 | 12 |
| 165.81 | 1.1 | 16 |
| 186.63 | 0.8 | 11 |
| 297.45 | 1.4 | 4 |
- 1.4Near Azusa, California, United States11-12 21:23
- 1.26 km NNW of Glendora, California, United States11-01 23:06
- 1.16 km WSW of Burbank, California, United States11-07 09:44
- 1.16 km NNW of Azusa, California, United States11-04 20:26
- 0.89 km NNW of Glendora, California, United States11-08 06:33
- 0.5Near El Monte, California, United States11-06 09:28
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports on SeismoAtlas
No reports yet.
Event id ci41570320. First recorded here 31 Oct 2026, 12:00:17 UTC. Solutions: USGS · CI (usgs:ci41570320). Cite as: SeismoAtlas, “M0.5 earthquake 6 km N of Altadena, California, United States”, https://seismoatlas.com/earthquake/ci41570320-m0-5-earthquake-6-km-n-of-altadena-california-united-states, data from USGS.
JSON: /api/v1/events/ci41570320. SeismoAtlas is not an official warning service.