VOLCANIC ACTIVITIES

The following table summarizes ’s unrests. Most of Kanlaon Volcano’s record of phreatic YEAR/ activity are clusters of minor outbursts in the form of NATURE OF ACTIVITY AFFECTED AREAS/REMARKS ash ejections of varying intensities and duration. DURATION Except in the 1902 activity during which a description 1866 Phreatic, mild of lava flow effusion was reported, most of Kanlaon’s 1881 Phreatic, mild recent historical activities were described as mild to 1883 July Phreatic, ashfall San Carlos City (ashfall) 1884 May – June Phreatomagmatic moderate ash ejections, which generated column 1893 Phreatic heights between 0.5- 3 km. The short ash explosions 1894 Phreatic

were accompanied by loud “booming sound” while 1898 June explosion type earthquakes were sometimes recorded 1902 Jan. 31 Strombolian, lava emission on the seismograph located on the volcano’s slope. 1904 Phreatic Significant but still minimal ashfall (with maximum 1905 Nov. 6 Phreatic, ashfall thickness of 3 mm) had been experienced in areas 1906 Jan. 16, Nov. 6 Phreatic, ashfall As far as Hinagaran within 6 km surrounding the volcano’s summit area. Barrios on the SE flank of the volcano 1927 Mar. 20 Phreatic, ashfall (ashfall) Some ash columns had been reported to reach more 1932 Dec. 23 – 1933 Jan. 6 than 4 km in height such as during the 1969, 1986 Phreatic, ashfall, tephra and 1996 eruptions. 1969 Oct. 10 – 29 fall, 6-km high eruption Six-km radius from the summit (ashfall) column Phreatic, 1.83-km high 1978 Mar. 22 – Sept. 2 Eruption Precursors: eruption column

Areas 1.5 km SW of summit, Phreatic, ashfall, 0.4-0.8 1985 Mar. 13 – Dec. 7 Cabagnaan, Mansalanao, Old Fabrica km high eruption column 1. Increase in frequency of volcanic tremors/quakes and Antipolay 2. Inflationary trend for geodetic measurements Phreatic, 4-km high Bgys at SE slope: Pula, Upper 1986 June 3 – Aug. 18 3. Increased steaming activity eruption column Masulog, Pantao, Tinago & Cabatuan 4. Sulfur stench observed at Cabagnaan and Ashfall deposits at the SW slope 1987 Apr. 24 Phreatic covering an area of approx. 2 km by Mambucal 6.5 km

5. Increased chloride concentration and lowering of Phreatic, ashfall, 0.3-1.0 1988 June 21 Mananawin (traces of ash) pH at Mambucal hot springs km high eruption column Mananawin, Pula, Upper Linotagan, Phreatic, 0.2-1.2 km high 1989 Oct. 25 – Dec. 5 Mansalanao, Haguimit, Yubo, Araal, eruption column Mansinaga,Guintubdan

Very mild ash explosion 1991 Feb. 13 reaching 0.5 km high TRACES OF ASH: Haguimit, La Granja, Mailum, Pontevedra, La Phreatic, ashfall, 0.8-1.0 1992 Jan.8, June 10 Carlota City and San Enrique; ASH high eruption column DEPOSIT OF 1-3 CM THICK: Araal, Yabo, Mansibanga and Guintubdan

Phreatic, 0.8-1.0 km high 1993 Aug. 25, Sept. 3 Light ashfall observed at City eruption column Western sector of the volcano (light Phreatic, 0.35-1.5 km high ashfall, trace to 1 mm thick) 1996 Aug. 10 – Oct. 14 eruption column CASUALTIES: 3 (due to initial explosion) 2002 Nov. 28 Ash explosion TRACES OF ASH: Cabagnaan 2002 Jan. – Mar. Seismic swarm TRACES OF ASH: Canlaon City proper, Upper Mananawin, Masulog, Series of ash explosions, Linothangan, Alebabay, Lucap, 2003 Mar. 7 – July 23 0.3-1.5 km high steam Biaknabatao , Cabagnaan, Old Ash puff of Kanlaon volcano viewed from Canlaon City proper (July 7, 2003) plume Fabrica, Upper Mansalanao & Sag- ang

LOCATION ACCESSIBILITY largest patch having an area of 100 sq. m. The thermal area is composed of hot grounds with Kanlaon Volcano (10o 24.7’ N, 123o 7.9’ E), is Kanlaon is located approximately 36 km numerous active steaming vents and a large number located in , central . It is one southeast of City. The volcano can be of compositionally diverse thermal springs which of the 6 most active volcanoes in the Philippines and reached by commercial airline from Manila via issue at low rates of outflow over a temperature range has had at least 23 episodes of historical activities Bacolod City. Commercial bus lines ply the route of 42°C to local boiling. since 1866. Kanlaon Volcano forms part of the west- from Bacolod City to Kanlaon City via the La Carlota- facing Negros volcanic arc which is the result of La Castellana-Magallon route. It generally takes 2 eastward subduction of the Sulu Basin along the hours to reach Canlaon City which is approximately Negros Trench. This arc has been active since the 10 km (aerial distance) southeast of the Kanlaon Miocene. Other volcanoes of the Negros Arc include summit. To reach the upper slopes of Kanlaon, one (from north to south) Mt. , Mt. and would need to hike. Cuernos de Negros.

PHYSICAL FEATURES

Kanlaon Volcano, which rises to 2435 meters above sea level (m asl), has a deformed cone forming a slightly elongate ridge trending north-south. It is a typical compound volcano whose edifice was built up by eruption of both lava and pyroclastic products, punctuated by an episode of sector collapse, edifice rebuilding and active vent migration through time as suggested by the nearly north-south

trending line of craters at the summit region. Two major rivers, Bago River (to the north) and Binalbagan River (to the south) define the boundary of the Kanlaon edifice and separate it from the other volcanic terrains such as Mandalagan Volcano to the north. Distinct lava lobes are prominent features found on the middle to upper southern slopes of the volcano. Gently sloping aprons of pyroclastic materials form the lower flanks of Kanlaon, especially to the southwest and northwest. The northern area on the other hand has steep sided ridges and deeply incised valleys where rivers cut through presumably older pyroclastic flow deposits. The volcano in general has a rugged terrain and thick vegetation cover that Ash column at Kanlaon October 8, 1996 makes access to the area more difficult.

Thermal manifestations in the area are in the form of hot springs and sulfide gas seepages. These are DEPARTMENT OF SCIENCE AND TECHNOLOGY found in Mambucal, Bucalan and Bungol. Mambucal thermal area is nested within a roughly semi-circular PHILIPPINE INSTITUTE OF VOLCANOLOGY depression (collapse structure) that defines the AND SEISMOLOGY Location map of Kanlaon volcano famous Mambucal Health Resort in Negros PHIVOLCS Bldg., C.P. Garcia Ave.,UP Campus, Diliman, Quezon City Tel. Nos. 426-1468 to 79 Occidental. It is located at the northwest slope of PHIVOLCS Website: www.phivolcs.dost.gov.ph Kanlaon at about 8 km from the crater. Mambucal has OCTOBER 2003 the largest cluster of thermal manifestations with the