Volcanic Eruptions at Ahyi Seamount
Right now
The most recent data we hold from USGS arrived 15 hours ago, and this point is in it.
Nothing else has been detected within 20 km in the last 24 hours.
Reported by USGS yesterday.
It is the 7th strongest of the 10 detections recorded within 20 km of this point since 23 July 2026. The last comparable one was on 10 September 2026. One more was recorded here in the fortnight before it.
What the source measured
USGS reported: NMI Ahyi Seamount YELLOW/ADVISORY - No plumes seen in satellite images; no significant geophysical signals.
USGS moved the alert level from UNASSIGNED to ADVISORY.
Nearby, since 23 July 2026
- September 10, 2026 · score 18 · 0.0 km
- September 3, 2026 · score 24 · 0.0 km
- August 27, 2026 · score 18 · 0.0 km
How we know
One source: USGS. Not yet confirmed by a second, independent source.
Our own score for this event is 18 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 | Volcanic Eruptions |
| Severity | Medium |
| Calamity Score (ours) | 18 / 100 |
| Legacy data-support index | 0.62/1 |
| Coordinates | 20.4370, 145.0300 |
| Nearest City | Saipan (586 km) |
| Urban exposure index (PEI) | 0 within 100 km |
| Impact Tier | minor |
| Timestamp | 2026-09-18T00:41:48.000Z |
| Source | https://volcanoes.usgs.gov/hans2/view/notice/DOI-USGS-NMI-2026-09-18T00:41:02+00:00 |
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_volcano. Occurrence: 2026-09-18T00:41:48.000Z.
First archived: 2026-09-18T00:56:38.856Z. Material modification: not recorded.
Retained revisions are prospective; earlier versions may be unavailable. No revision entry does not prove that a record never changed.
2026-09-18T19:25:36.962Z · data_change
Index 18 → 18; severity medium → medium; version 5 → 5.
2026-09-18T18:52:55.688Z · data_change
Index 18 → 18; severity medium → medium; version 5 → 5.
Score Breakdown
Technical Details
| VolcanoName | Ahyi Seamount |
| VolcanoId | 284141 |
| AlertLevel | ADVISORY |
| ColorCode | YELLOW |
| ObservatoryCode | nmi |
| NvewsThreat | Very Low Threat |
| PreviousAlertLevel | UNASSIGNED |
| PreviousColorCode | UNASSIGNED |
Safety Information
During volcanic activity: follow evacuation orders from authorities. Volcanic ash can damage lungs — wear N95 masks or wet cloth over nose and mouth. Stay indoors during ashfall, close windows, and avoid driving. Lahars and pyroclastic flows can travel at high speeds — stay away from valleys and river channels near the volcano.
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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