Data: Smithsonian Global Volcanism Program (volcano.si.edu), confirmed Common-Era eruptions only. “Years quiet” is computed as of 2026. All figures describe the recorded eruption history and do not forecast future activity.
How “overdue” is measured here — and why it's a myth
For every volcano we take its confirmed eruptions in the Common Era (year 1 onward), measure the gap between each pair, and average them. The current quiet spell is the time since the last confirmed eruption. Divide one by the other and you get how many times its average a volcano has now been silent. We only include volcanoes with at least eight confirmed eruptions and an average gap of at least 20 years, so a volcano that erupts almost every year (and whose “gaps” are really reporting granularity) can't produce a meaningless number.
The catch — and the reason scientists dislike the word “overdue” — is that eruptions are not periodic. An average of a handful of irregular gaps is not a timetable. That is exactly why we also show each volcano's longest recorded gap: of the 24 volcanoes here, only 6 have actually exceeded the longest quiet spell in their own record. Every other one has been this quiet before, and then erupted again anyway — or didn't.
Worked example
Fujisan (Japan) has 29 confirmed Common-Era eruptions, averaging one every ~59 years. Its last was 1,707 CE, so it has been quiet about 319 years — roughly 5.4× its average. Yet its longest recorded gap is 352 years, so even this is within what the volcano has done before.
The 10 volcanoes quietest relative to their own average
| # | Volcano | Country | Quiet now | × average |
|---|---|---|---|---|
| 1 | Fujisan | Japan | 319 yr | 5.4× |
| 2 | Taveuni | Fiji | 476 yr | 5× |
| 3 | Ragang | Philippines | 110 yr | 4.8× |
| 4 | Atitlan | Guatemala | 173 yr | 4.5× |
| 5 | Iwakisan | Japan | 163 yr | 4.3× |
| 6 | Ischia | Italy | 724 yr | 4× |
| 7 | Serua | Indonesia | 105 yr | 4× |
| 8 | Mono-Inyo Craters | United States | 646 yr | 3.8× |
| 9 | Hakusan | Japan | 367 yr | 2.8× |
| 10 | Katla | Iceland | 108 yr | 2.2× |
Where this fits
The best-known “overdue” debate is Yellowstone — and the math there is a myth, as we explain in is Yellowstone going to erupt. For a single volcano's honest repose arithmetic, see Mount Fuji (319 years quiet against a ~59-year average, but still short of its 352-year record). To see what is actually erupting or on alert right now, use the active volcanoes tracker and the live erupting-now dashboard; for how often volcanoes erupt in general, the most active volcanoes ranking takes the opposite view.