Right now
The most recent data we hold from USGS arrived 27 minutes ago, and this point is not in it. We record detections, not passes: an absence is not proof that nothing is there.
One other detection within 20 km in the last 24 hours, <1 km from here.
Reported by USGS today.
No stronger detection stands among the 29 recorded within 20 km of this point since 14 March 2026 — 28 others scored the same. Another comparable one was recorded here earlier the same day. 7 more were recorded here in the fortnight before it.
What the source measured
USGS reported: 20 km WSW of Petrolia, CA
USGS recorded magnitude 3.5 at a depth of 20 km.
This is the lowest magnitude we have recorded at this point, over 131 readings since 16 September 2026 — the previous range was 3.52 to 3.65.
Nearby, since 14 March 2026
- July 12, 2026 · score 0 · 0.5 km
- June 29, 2026 · score 0 · 2.2 km
- May 8, 2026 · score 0 · 2.9 km
How we know
One source: USGS. Not yet confirmed by a second, independent source.
Our own score for this event is 0 out of 100.
This is our versioned heuristic index, not source severity or a calibrated probability. Urban PEI does not count unique people.
Computed under scoring rules v5. Rows carrying other versions were judged by different rules and are not directly comparable.
Event Data
| Type | Earthquakes |
| Severity | Low |
| Calamity Score (ours) | 0 / 100 |
| Legacy data-support index | 0.62/1 |
| Coordinates | 40.2853, -124.5187 |
| Nearest City | Eureka (65 km) |
| Urban exposure index (PEI) | 0 within 15 km |
| Impact Tier | minor |
| Timestamp | 2026-09-16T14:34:52.440Z |
| Source | https://earthquake.usgs.gov/earthquakes/eventpage/nc75436587 |
Physical priority index · v5. Heuristic priority, not calibrated probability, predictive accuracy or damage. The legacy data-support index combines assigned source support and field availability. Urban PEI is distance-weighted and does not count unique people; zero does not establish that nobody is present. Model cards.
Source and revision timeline
Source: usgs. Occurrence: 2026-09-16T14:34:52.440Z.
First archived: 2026-09-16T14:45:17.470Z. Material modification: 2026-09-16T19:07:52.477Z.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
2026-09-16T21:04:24.114Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T20:47:59.302Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T19:57:53.357Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T19:35:57.949Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T19:13:17.052Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T19:07:52.477Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T18:51:31.810Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T18:40:36.653Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T17:34:47.282Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T17:23:53.820Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T17:18:25.085Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T17:02:10.968Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T16:56:45.415Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T16:01:52.145Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:50:44.254Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:39:53.808Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:34:27.856Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:28:27.018Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:17:38.787Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
2026-09-16T15:01:28.702Z · data_change
Index 0 → 0; severity low → low; version 5 → 5.
Score Breakdown
Technical Details
| Mag | 3.52 |
| Depth | 20.15 |
| Tsunami | false |
| Felt | 18 |
| Mmi | 2.9 |
| Sig | 197 |
| Usgs Dyfi Mag | 3.52 |
| Usgs Dyfi Depth | 20.15 |
| Usgs Dyfi Felt | 18 |
| Usgs Dyfi Cdi | 3.4 |
| Usgs Dyfi CdiDescription | Weak |
| Usgs Dyfi Mmi | 2.9 |
| Usgs Dyfi Sig | 197 |
| Usgs Dyfi Tsunami | false |
| Usgs Dyfi Place | 20 km WSW of Petrolia, CA |
| Usgs Dyfi Types | ,dyfi,focal-mechanism,moment-tensor,nearby-cities,origin,phase-data,scitech-link,shakemap, |
| MergedSources | [{"id":"usgs_dyfi_nc75436587","source":"usgs_dyfi","severity":"low","severityValue":21.12,"timestamp":1789569292440,"latitude":40.2853333333333,"longitude":-124.518666666667}] |
Safety Information
If you feel shaking: Drop, Cover, and Hold On. Move away from windows, heavy objects, and exterior walls. After shaking stops, check for injuries and structural damage. Be prepared for aftershocks, which can occur minutes to months after the mainshock. Follow instructions from local emergency management authorities.
Series begins 8 March 2026. Comparisons refer to that period only. Collection gap: 14-26 August 2026.
This data is aggregated algorithmically from scientific sources. Not a replacement for official emergency warnings.
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