Biliran Inactive Volcano

The Inactive Volcanoes in Biliran

Do you know that Biliran Island has 14 inactive volcanoes? Only Mt. Suiro is active.

The Inactive volcanoes:
1. Biliran
2. Tabuanan
3. Caraycaray
4. Maliwatan
5. Guiausan
6. Gunasan
7. Camalobagoan (Asluman Volcano)
8. Capinyayan
9. Sayao
10. Giron
11. Vulcan (Biliran)
12. Tamburok (Tagburok Mt. Busales)
13. Lauaan
14. Ascuero

Source: PhiVolcs, HazardHunterPH

Biliran Volcano

Biliran is an solfataric active volcano located in the island province of Biliran in the Philippines. The volcano caused the formation of the island. 12.3 km west of Caibiran town  (11°39’N, 124°32.1’E)

Geological features

  • Rock Type: Hornblende andesite containing greenish and black hornblende
  • Tectonic Setting: Biliran Volcano is part of the curvilinear belt of Quaternary volcanoes in eastern Philippines, parallel to Phil. Trench to the east

Volcanic activity

  • Number of Historical Eruptions: 1
  • Latest Eruption/Activity: September 26, 1939
  • Site: crater
  • Eruption Character: Debris avalanche
  • Affected Areas/Remarks: Ashfall at Caibiran and adjoining areas (6.35 cm thick deposits)
  • Monitoring activity: Short-term monitoring in 1954

Physical features

  • Hotsprings:
    1. Central Biliran – Libtong Thermal Areas (12 hot springs and one bubbling pool)
    2. North Biliran – Panamao Thermal Area
    3. Anas Thermal Area
    4. South Biliran – Kalambis Thermal Area
  • Adjacent Volcanic Edifice:
    1. Panamao (107 m asl)
    2. Gumansan (1064 m asl)
    3. Lauan (1187 m asl)
    4. Suiro (1301 m asl)


Number of Historical Eruptions:  1
Date:  1939 Sept. 26
Site:  crater
Eruption Character:  Debris avalanche (?)

Affected Areas: Ashfall at Caibiran and adjoining areas (6.35 cm thick deposits)


An investigation was conducted by then Commission on Volcanology (now PHIVOLCS) on November 12, 1954 at Mt. Biliran to confirm reports published in local newspapers that the volcano was showing signs of volcanic activity.  Local earthquakes accompanied by rumbling sounds were reportedly felt at places near the volcano.  Furthermore, thick steam clouds rising from the volcano and drying up of vegetation at the upper slopes were reportedly observed by boat passengers and fishermen.  Data gathered, however, by the investigating team showed that no unusual volcanic activity took place.

The Philippines has a total of 23 active volcanoes, including one in Biliran.

Active Volcano in the Philippines

Source: Philvolcs

Mt. Suiro

Mount Suiro is a 2,495 ft / 761 m mountain peak in Caibiran, Biliran, Philippines. Based on peakery data, it ranks as the 831st highest mountain in Philippines.

Mt. Suiro, the tallest mountain on Biliran Island located in the vicinity of Caibiran and Cabucgayan, as viewed from the Caibiran short cut road. Now a dormant volcano, it erupted in 1939.

Mt. Suiro, the tallest mountain on Biliran Island located in the vicinity of Caibiran and Cabucgayan, as viewed from the Caibiran short cut road. Now a dormant volcano, it erupted in 1939.

The description fits Mt. Suiro (Surio in the GVP website) in Caibiran town, the tallest peak southeast of the island, which became dormant after 1939.

An unnamed Internet blogger said that the 1939 eruption was from the crater and that it caused an avalanche of debris and 6.35 cm. thick ashfall at Caibiran and adjoining areas.

The known volcanic eruptions in Biliran in 1669, 1800 and 1939 present a pattern that such event occurs in the island every 130 years or so. Thus, the next eruption could possibly happen decades from now in 2069, but not in 2007.

Biliran Island has many thermal, mud pools and hot springs such as in Catmon, Libtong in Naval and the Mainit Hot Spring in Brgy. Villa Vicenta, Caibiran that have become popular tourist attractions in Eastern Visayas.

Mt. Suiro Trivia

Mt. Panamao erupted around 1669, not in 1939. The second recorded eruption in Biliran Island during historic time was around 1800, or 131 years later, and the volcano’s mouth was in the vicinity of the present drilling site of Biliran Geothermal, Inc., then called Tinago. The third volcanic eruption in the island was in 1939, or 139 years from the second one, and its mouth was in Mt. Suiro in Caibiran. – Prof. Rolando Borrinaga

Aerial view of Brgy. Cabibihan, Caibiran, Biliran. Photo by Jalmz

Cabibihan Caibiran

Municipality of Caibiran, Biliran Province

Cabibihan Caibiran, Biliran Island, Philippines

It has a population of 1,405 (2010 Census).


Patron Saint:

Barangay Officials





Tourist Attractions

In Pictures




History of Biliran Geothermal

Exploration and Development History

Biliran Island lies immediately to the north of Leyte, alongside the active Philippines Fault. In 1979-1980, geothermal exploration started in Biliran with the inventory of surface hydrothermal features and geological reconnaissance by PNOC-EDC and KRTA.

  • 1979 – 1980 – Geoscientific studies (EDC/KRTA)

Geophysical surveys were conducted between 1980 to 1981 including Schlumberger resistivity traversing (SRT), vertical electrical sounding (VES), and dipole-dipole resistivity survey (DRS). In 1981, DSIR reviewed all surface exploration work done in Biliran as part of New Zealand-Philippines Energy Cooperation Program.

  • 1981 –  1982 – Exploration Drilling
    • BN-1 = neutral-CI w/ T = 250°C (low WHP, did not discharge)
    • BN-2 = neutral-C1 w/ T = 210°C (failed to sustain discharge due to mineral scaling)
    • BN-3 = acid CI-SO4, pH 3 at weirbox, T = 330°C (cement plugged due to corrosion)

Based on these studies, three prospective targets were delineated, namely: Vulcan, Kalambis and Panamao areas.
Among these three, Vulcan area was judged most impressive because of its close association with solfataric activiry. In
1982, three exploration wells (BN-1, BN-2, and BN-3) were drilled to test the geothermal potential of Vulcan Area.

  • 1991 – 1993 Additional geoscientific  studies (PNOC-EDC)
    • Geology Survey
    • Geochemical sampling
    • Resistivity  (VES)


Figure 1: Different Hydrothermal Systems in Biliran

Figure 1: Different Hydrothermal Systems in Biliran

Figure 2: The Geothermal Model of the Vulcan-Libtong Area

Figure 2: The Geothermal Model of the Vulcan-Libtong Area

  • 2004 DOE looking for investor
  • 2007 DOE offers Biliran for bidding
  • 2008 Geothermal Service Contract awarded to Biliran Geothermal, Inc. (BGI)
  • 2009-20010
    • GRESC
    • Additional Surface Exploration
      • MT Survey
      • Water/Gas resampling
      • Detailed Structural Mapping
  • 2013 to present Confirmatory Drilling
Figure 3: Simplified Geological Map of Biliran

Figure 3: Simplified Geological Map of Biliran


Biliran Geothermal Gallery



Apuada, N.A. (1992): The Resistivity Signature of Biliran
Island. PNOC-EDC Internal Report. Makati,

KRTA (1986): Evaluation of the Biliran Geothermal
Prospect. PNOC-EDC Internal Report. Makati,

Ramos-Candelaria and Baltasar, A.S.J (1993): Geochemical
and Isotopic Investigation of Biliran Geothermal
Discharges. PNOC-EDC Internal Report. Makati,

Pagado, E.S., Camit, G.R.A and Rosell, J.B (1993): The
Geology and Geothermal Systems of Biliran Island.
PNOC-EDC Internal Report. Makati, Philippines.

Department of Energy (DOE)

Photos by Jalmz