Stratovolcano โข Bicol, Philippines
Frequent phreatic (steam-driven) eruptions. Phreatic eruption April 2025, ongoing elevated unrest.
Under active unrest
Bulusan is under PHIVOLCS Alert Level 1 โ unrest is elevated above background and an eruption is a realistic near-term possibility. Our model estimates a 38.8% chance of an eruption in the next 12 months โ about one eruption every ~7 years on average. Its most recent known eruption was 2025.
Statistical estimate, not a prediction โ low confidence. Always follow official PHIVOLCS advisories. How this is calculated โ
38.8%
1-year
4%
30-day
~7y
recurrence
12.770ยฐ, 124.050ยฐ ยท Philippines ยท 12 nearby earthquakes
Sorsogon, Bicol ยท Stratovolcano
low confidenceยท 6 stationsยท hazard map โ
๐ Review and update emergency preparedness. Monitor official bulletins.
Active unrest puts this ~3.4ร above the long-run baseline, driven by phivolcs alert level 1, recent eruptive episode.
How this number is built
What's driving it
Low-level unrest (abnormal)
Activity level 2/3
b=0.66 (low) ยท Mc 2.2 ยท n=657
Statistical models indicate significantly elevated probability. Prudent preparedness recommended.
Active unrest puts this ~3.4ร above the long-run baseline, driven by phivolcs alert level 1, recent eruptive episode.
Alert Level 1
Low-level unrest (abnormal) โ slightly elevated chance of steam-driven activity.
Basis: PHIVOLCS Volcano Alert Level System
Activity level 2/3
A vigorous open hydrothermal system raises the chance of steam-driven (phreatic) activity.
Basis: PHIVOLCS hydrothermal monitoring
3 eruptions in the last 10 years โ an active eruptive episode.
Volcanic activity clusters in episodes โ recent eruptions raise near-term probability.
Basis: GVP eruption history
b = 0.66 (low) ยท Mc 2.2 ยท n=657
Low b-value (0.66) suggests high stress accumulation and potential for larger events
Basis: GutenbergโRichter b-value (Aki 1965; Wiemer & Wyss 2000)
~1 yr since last vs a ~7-yr average (ratio 0.14)
Erupted recently (~1 yr ago vs a ~7-yr average) โ repose does not add near-term risk.
Basis: Weibull/renewal repose model (Bebbington & Lai 1996; Marzocchi & Bebbington 2012)
25 eruptions since 1852 โ ~1 per 7 yr
Anchor โ the average eruption frequency this volcano has shown historically.
Basis: Smithsonian Global Volcanism Program eruption record
No qualifying large earthquakes in range/time window
Large nearby earthquakes can perturb the magma/hydrothermal system (static + dynamic stress).
Basis: Nishimura (2017) GRL 44; Jenkins et al. (2024) Volcanica
0 events within 15 km ยท 0.2/day
Elevated shallow, near-field seismicity can indicate magma or fluid movement.
Basis: Volcano-seismic monitoring (PHIVOLCS / USGS)
No coherent migration detected
Insufficient data for depth migration analysis
Basis: Hypocenter migration (Roman & Cashman 2006)
No acceleration detected
Accelerating seismicity can precede failure of the edifice/conduit.
Basis: Material-failure forecasting (Voight 1988; Kilburn 2003)
No significant clustering
Swarms and clusters indicate stress concentration or fluid migration beneath the edifice.
Basis: Seismic cluster analysis
Erupted recently (~1 yr ago vs a ~7-yr average) โ repose does not add near-term risk.
Stratovolcano โ predominantly phreatic (steam-driven); VEI 1โ2
Typical explosivity โ VEI 1
Detailed instrument readouts
Low-level unrest (abnormal)
0.66 ยฑ 0.03
Mc 2.2 ยท n=657
Low b-value (0.66) suggests high stress accumulation and potential for larger events
No coherent migration detected
Insufficient data for depth migration analysis
No acceleration detected
841
analyzed
213
M3+
25
M4+
7
M5+
1
<5km deep
0
<15km away
0.2
ev/day
Smithsonian GVP eruption frequency โ about one eruption every ~7 years.
Official unrest classification โ the strongest near-term signal.
Product of b-value, depth migration, acceleration, triggering & swarm signals.
Erupted recently (~1 yr ago vs a ~7-yr average) โ repose does not add near-term risk.
Confidence: Limited monitoring or sparse local seismicity โ the estimate leans on the long-run base rate.
How this is calculated โModeled from PHIVOLCS alert level + live seismicity + eruption history. See the Risk Analysis dashboard for all volcanoes side by side.
explosive ยท moderate explosivity
Largest recorded: VEI 3
Most eruptions ~VEI 2; no large (VEI โฅ 4) eruption in the documented record.
26 dated eruptions over ~5075 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
1,559m
Elevation
2025
Last Eruption
Stratovolcano
Type
25
Recorded Eruptions (since 1852)
~7y
Avg. Recurrence
2025
Last Eruption
Baseline eruption rate derived from Smithsonian GVP confirmed-eruption frequency. Current eruption probability (incorporating PHIVOLCS alert level and live seismicity) is on the Risk Analysis dashboard.
Stratovolcano โ predominantly phreatic (steam-driven); VEI 1โ2
Typical explosivity โ VEI 1
Erupted recently (~1 yr ago vs a ~7-yr average) โ repose does not add near-term risk.
Live risk direction, the full evidence ledger and seismic precursors are on the Risk Analysis dashboard.
005 km S 25ยฐ E of City Of Sorsogon (Sorsogon)
115.0km deep โข 19km away
008 km S 86ยฐ E of Gubat (Sorsogon)
31.0km deep โข 22km away
012 km S 40ยฐ E of Prieto Diaz (Sorsogon)
33.0km deep โข 31km away
010 km S 84ยฐ W of Bulan (Sorsogon)
21.0km deep โข 31km away
010 km N 80ยฐ W of Prieto Diaz (Sorsogon)
33.0km deep โข 33km away
010 km N 13ยฐ W of City Of Sorsogon (Sorsogon)
24.0km deep โข 34km away
CATANDUANES, PHILIPPINES
95.0km deep โข 34km away
CATANDUANES, PHILIPPINES
95.0km deep โข 35km away
010 km S 64ยฐ E of Manito (Albay)
35.0km deep โข 36km away
010 km S 22ยฐ W of Rapu-rapu (Albay)
31.0km deep โข 37km away
009 km S 13ยฐ W of Rapu-rapu (Albay)
33.0km deep โข 38km away
011 km N 63ยฐ E of Batuan (Masbate)
28.0km deep โข 39km away
Coordinates
12.7700ยฐN, 124.0500ยฐE
Region
Philippines and SE Asia
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
Bulusan is under PHIVOLCS Alert Level 1 โ unrest is elevated above background and an eruption is a realistic near-term possibility. Based on Bulusan's eruption history and current PHIVOLCS Alert Level 1, our model estimates roughly a 38.8% chance of an eruption within the next 12 months (about one eruption every 7 years on average). This is a statistical estimate, not a definite prediction โ always follow official PHIVOLCS advisories.
Bulusan's most recent known eruption was 2025 (per the Smithsonian Global Volcanism Program record).
Bulusan is classified as active. It is a stratovolcano in Bicol, Philippines, rising to 1,559 m.
About 180,000 people live within 30 km of Bulusan. The current modeled hazard level is very high. Local hazard zones and typical eruption size are detailed on this page.
Bulusan is located in Bicol, Philippines, at 12.770ยฐ, 124.050ยฐ, with a summit elevation of 1,559 m.