2. TAAL VOLCANO ISLAND : 23 square kilometers or 2,300 Ha in area; highest point of the island: 311 meters above sea level (SW rim of the Main Crater). The volcano – geomorphic features of the island suggest that there are at least 35 eruption cones and 47 craters of depressions formed either by direct explosive eruptions or collapsed subsidence. The underwater bathymetry suggests the presence of about 35 different volcanic landforms. This strongly indicates that eruption centers of Taal Volcano are numerous, complex and may erupt from any other points. MAIN CRATER : 1.9 km in diameter; and TAAL CALDERA : 25 km across. GENERAL INFORMATION
14. Effect s of base surge at Taal Volcano during the 1911 and 1965 eruptions Taal base surge, 1965 PYROCLASTIC FLOW/ BASE SURGE - turbulent mass of ejected fragmented volcanic materials (ash and rocks), mixed with hot gases that flow downslope/ away from crater at very high speed ( > 60 kph)
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16. The 1965 eruption of Taal Volcano generated a seiche at Taal Lake killing several people crossing the lake. Seiches/Tsunami and flooding 1911 – generated seiches 2.5-3.0 m high above lake level 1965 – generated seiches 4.7 m high above the lake level and swept inshore as much as 80 m
17. Taal Volcano Alert Signals Alert Level Criteria Interpretation 0 Background, quiet No eruption in foreseeable future. 1 Low level seismicity, fumarolic, other activity Magmatic, tectonic or hydrothermal disturbance; no eruption imminent. 2 Low to moderate level of seismicity, persistence of local but unfelt earthquakes. Ground deformation measurements above baseline levels. Increased water and/or ground probe hole temperatures, increased bubbling at Crater Lake. A) Probable magmatic intrusion; could eventually lead to an eruption. B) If trend shows further decline, volcano may soon go to level 1 3 Relatively high unrest manifested by seismic swarms including increasing occurrence of low frequency earthquakes and/or harmonic tremor (some events felt). Sudden or increasing changes in temperature or bubbling activity or radon gas emission or crater lake pH. Bulging of the edifice and fissuring may accompany seismicity. A) If trend is one of increasing unrest, eruption is possible within days to weeks. B) If trend is one of decreasing unrest, volcano may soon go to level 2 4 Intense unrest, continuing seismic swarms, including harmonic tremor and/or “low frequency earthquakes” which are usually felt, profuse steaming along existing and perhaps new vents and fissures. Hazardous explosive eruption is possible within days. 5 Base surges accompanied by eruption columns or lava fountaining or lava flows. Hazardous eruption in progress. Extreme hazards to communities west of the volcano and ashfalls on downwind sectors.
