References 388% CONFIDENCEOverall confidence: 88%How well the pin's source and references back up its dates.Weighted average of how firmly 3 references, the source included, support the pin's start and end times; a reference counts half as much for every 180 days older than the newestShow all pins at 75% confidence or better
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
- [1]90%usgs.gov/volcanoes/mount-st-helensusgs.gov· Posted Sep 21, 2026· Starts May 18, 1980 ✓· 33% of score
The moment is recorded to the second: "An earthquake at 8:32:11 am PDT (UTC-7) on May 18, 1980, caused the entire weakened north face to slide away", which is 15:32:11 UTC.
- [2]85%1980 eruption of Mount St. Helens - Wikipediaen.wikipedia.org· Added Sep 21, 2026· 33% of score
Carries the origin time to the second, the landslide and lateral-blast sequence, the ash distribution, the death toll and the damage figure quoted here.[1]
- [3]90%Global Volcanism Program | St. Helensvolcano.si.edu· Added Sep 21, 2026· 33% of score
The Smithsonian's eruption database for St. Helens, the authority for the volcano's identity and eruptive record.[1]
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