Caldera โข Sumatra, Indonesia
Unlikely in any given year
Toba erupts infrequently, so the chance in any single year is low. Our model estimates a 2.8% chance of an eruption in the next 12 months โ about one eruption every ~35 years on average. Its most recent known eruption was -71000.
Statistical estimate, not a prediction โ very low confidence. Always follow official volcano observatory advisories. How this is calculated โ
2.8%
1-year
0.2%
30-day
~35y
recurrence
2.580ยฐ, 98.830ยฐ ยท Indonesia ยท 12 nearby earthquakes
2.8%
1-year probability
0.2%
30-day
~35y
Avg. recurrence
low
Risk level
~1 eruption every 35 yr โ the GVP eruption frequency blended toward a caldera prior by how complete the record is.
Sparse / largely unknown history โ the rate is dominated by a volcano-type prior, with wide uncertainty.
Most eruptions ~VEI 3; capable of large (VEI โฅ 4) events โ largest recorded VEI 8. ~0.6% 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: Very little monitoring data โ this is essentially the historical base rate, with wide 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 0.8โ9.5% (confidence very low; no live seismic feed for this volcano). Philippine volcanoes additionally use live PHIVOLCS alert levels and seismicity โ see the Risk Analysis dashboard.
severe ยท very high explosivity
Most eruptions ~VEI 3; capable of large (VEI โฅ 4) events โ largest recorded VEI ~7.
Sparse / largely unknown history โ the rate is dominated by a volcano-type prior, with wide uncertainty.
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
2,157m
Elevation
-71000
Last Eruption
VEI 8
Explosivity Index
Caldera
Type
21 km SSE of Parapat, Indonesia
149.1km deep โข 21km away
29 km SSE of Tomok Bolon, Indonesia
156.7km deep โข 23km away
29 km S of Parapat, Indonesia
133.8km deep โข 24km away
10 km NNE of Parapat, Indonesia
146.5km deep โข 25km away
10 km ENE of Parapat, Indonesia
148.9km deep โข 25km away
17 km NNE of Parapat, Indonesia
164.7km deep โข 32km away
32 km SSE of Parapat, Indonesia
160.2km deep โข 32km away
43 km SSW of Tomok Bolon, Indonesia
10.2km deep โข 35km away
47 km S of Tomok Bolon, Indonesia
23.6km deep โข 40km away
29 km E of Parapat, Indonesia
169.3km deep โข 41km away
34 km ESE of Parapat, Indonesia
158.4km deep โข 42km away
49 km S of Tomok Bolon, Indonesia
21.0km deep โข 42km away
Coordinates
2.5800ยฐN, 98.8300ยฐE
Region
Indonesia
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
Toba erupts infrequently, so the chance in any single year is low. Based on Toba's eruption history, our model estimates roughly a 2.8% chance of an eruption within the next 12 months (about one eruption every 35 years on average). This is a statistical estimate, not a definite prediction โ always follow official volcano observatory advisories.
Toba's most recent known eruption was -71000 (per the Smithsonian Global Volcanism Program record).
Toba is classified as potentially active. It is a caldera in Sumatra, Indonesia, rising to 2,157 m.
About 500,000 people live within 30 km of Toba and roughly 5,000,000 within 100 km. The current modeled hazard level is low. Local hazard zones and typical eruption size are detailed on this page.
Toba is located in Sumatra, Indonesia, at 2.580ยฐ, 98.830ยฐ, with a summit elevation of 2,157 m.