Complex volcano โข Honshu, Japan
Possible, not imminent
An eruption at Zao in any given year is a real but minority possibility. Our model estimates a 12.1% chance of an eruption in the next 12 months โ about one eruption every ~8 years on average. Its most recent known eruption was 1940.
Statistical estimate, not a prediction โ medium confidence. Always follow official volcano observatory advisories. How this is calculated โ
12.1%
1-year
1.1%
30-day
~8y
recurrence
38.143ยฐ, 140.447ยฐ ยท Japan ยท 12 nearby earthquakes
12.1%
1-year probability
1.1%
30-day
~8y
Avg. recurrence
elevated
Risk level
~1 eruption every 8 yr โ the GVP eruption frequency blended toward a complex volcano prior by how complete the record is.
51 dated eruptions over ~9540 yr โ a well-documented record the rate can rely on.
Most eruptions ~VEI 2; capable of large (VEI โฅ 4) events โ largest recorded VEI 4. ~0.5% chance of a VEI โฅ 4 event this year.
A recently active volcano gets a higher near-term rate; a long-dormant one is tempered.
No live PHIVOLCS/seismic feed for this volcano, so short-term precursors and alert levels are not applied.
Confidence: A monitoring network and a multi-eruption history constrain the estimate, but with meaningful uncertainty.
How this is calculated โPoisson estimate from the GVP eruption frequency, blended toward a volcano-type prior by how complete the record is and adjusted for recency โ 1-year range 8.8โ16.5% (confidence medium; no live seismic feed for this volcano). Philippine volcanoes additionally use live PHIVOLCS alert levels and seismicity โ see the Risk Analysis dashboard.
explosive ยท high explosivity
Largest recorded: VEI 4
Most eruptions ~VEI 2; capable of large (VEI โฅ 4) events โ largest recorded VEI 4.
51 dated eruptions over ~9540 yr โ a well-documented record the rate can rely on.
Size from the volcano's VEI record combined with the global eruption sizeโfrequency relation; the record grade reflects how complete its eruptive history is โ sparse records lean on a volcano-type prior with wider uncertainty. How this is calculated โ
1,841m
Elevation
1940
Last Eruption
VEI 2
Explosivity Index
Complex volcano
Type
8 km E of Yamagata, Japan
101.6km deep โข 10km away
7 km NNW of Hobaramachi, Japan
130.5km deep โข 30km away
12 km ESE of Yonezawa, Japan
98.7km deep โข 35km away
12 km ENE of Nihommatsu, Japan
88.6km deep โข 59km away
21 km W of Minami-Sลma, Japan
103.9km deep โข 64km away
9 km SSE of Higashimatsushima, Japan
75.8km deep โข 70km away
6 km N of Furukawa, Japan
91.8km deep โข 71km away
34 km ESE of Marumori, Japan
63.8km deep โข 71km away
1 km S of Wakuya, Japan
105.5km deep โข 74km away
18 km NE of Shinj?, Japan
108.8km deep โข 80km away
6 km WNW of K?riyama, Japan
99.4km deep โข 81km away
13 km NNE of Wakuya, Japan
108.6km deep โข 85km away
Coordinates
38.1430ยฐN, 140.4470ยฐE
Region
Japan, Taiwan, Marianas
Bars are relative to the 100 km total.
๐ Scientific Note: Volcanic risk assessments use peer-reviewed seismic-volcanic correlation models (Nishimura 2017, Jenkins 2024). These represent statistical probabilities, not predictions. Always follow official PHIVOLCS advisories.
How this is calculated โFAQ
An eruption at Zao in any given year is a real but minority possibility. Based on Zao's eruption history, our model estimates roughly a 12.1% chance of an eruption within the next 12 months (about one eruption every 8 years on average). This is a statistical estimate, not a definite prediction โ always follow official volcano observatory advisories.
Zao's most recent known eruption was 1940 (per the Smithsonian Global Volcanism Program record).
Zao is classified as active. It is a complex volcano in Honshu, Japan, rising to 1,841 m.
About 500,000 people live within 30 km of Zao and roughly 2,000,000 within 100 km. The current modeled hazard level is elevated. Local hazard zones and typical eruption size are detailed on this page.
Zao is located in Honshu, Japan, at 38.143ยฐ, 140.447ยฐ, with a summit elevation of 1,841 m.