T A A L V O L C A N O U P D A T E 21june2010Presentation Transcript
TAAL VOLCANO UPDATE June 2010 JAIME S. SINCIOCO OIC, Volcano Monitoring and Eruption Prediction Division Philippine Institute of Volcanology and Seismology Department of Science and Technology
TAAL VOLCANO ISLAND: 23 sq km in area; highest point of the island: 311 m asl (SW rim of the Main Crater) MAIN CRATER: 1.9 km in dia.; blue-green in color; 4 m asl; deepest point: 76 m; site of 12 eruptions from 1749 to 1911 TAAL CALDERA: 25 km across; formed between 140,000 to 5,380 B.P.; major adjacent volcanic edifices: Mt. Sungay, Mt. Batulao, Mt. Macolod, Mt. Malepunyo & Mt. Makiling No. of recorded eruptions of Taal: 33 since 1572 Latest eruption: 03 October 1977 Source: HIGP, Univ. Hawaii
NATURE OF ERUPTION
Steam-driven eruptions caused by contact of groundwater with hot country rocks (no magma involved)
Produce short ash columns, ashfall
Usually precursory to magmatic eruptions
Weak to violent eruption of gas-charged fluid magma characterized by lava fountaining and flowing
Produce lava flows
STROMBOLIAN 1966 1969 PHREATOMAGMATIC
Very violent eruption generated by the explosive contact of erupting magma with water
Produce voluminous, slightly tall ash columns, laterally-projected pyroclastic currents (base surges) and blasts
PLINIAN 1991 Pinatubo eruption (Plinian)
Very explosive, energetic release of voluminous magmatic gas, fragmented magma which propel with great force high in the air, forming huge mushroom clouds
Very tall eruption column, penetrating stratosphere
Produce extensive ashfall, pyroclastic flows, large crater
1965 eruption site (Mt. Tabaro) 1911 eruption site (Main Crater)
Barangays and sitios of Taal Volcano Island belong to three municipalities.
Brgy. San Isidro (Tibag) – Sitios Balantoc & Panikihan
Brgy. Tabla – Sitios Looc , Bignay, Pira-piraso &Tuoran
Brgy. Pulang Bato – Sitio Saluyan
Taal Volcano Island is a Permanent Danger Zone.
It might be affected by various volcanic processes during eruptions that may originate anywhere in the Island considering that it has 47 eruption centers.
Permanent habitation, i.e. continuous occupancy of people, in the Volcano Island is not allowed,
The whole Volcano Island was declared as a National Park during the term of President Ferdinand E. Marcos under Presidential Proclamation (PP) No. 235.
On Oct. 6, 1996, President Fidel V. Ramos, through PP No. 906, declared Taal Volcano Island National Park a Protected Area under Category of Protected Landscape
Alert Level 2
Increasing number and size of volcanic earthquakes detected daily; appearance of low frequency type volcanic quake; s ome of the recorded volcanic earthquakes were felt at Calauit and Pira-piraso with intensities ranging from 1-3 and accompanied by rumbling sounds .
Increasing temperature of Main Crater Lake (34°C as of May 24, 2010 compared to 32°C as of May 11, 2010); measurement as of June 8, 2010 is 33.5°C);
Above normal values of Mg/Cl, SO4/Cl and total dissolved solids (chemical composition)
Increasing trends shown by continuous ground temperatures and total magnetic field measurements by PHIVOLCS-EMSEV at Daang Kastila and Main Crater Lake
Occasional intensification of steaming activities at the northern and northeastern side of Main Crater; sometimes accompanied by audible hissing sounds
Slight inflation since 2004 as measured by precise leveling; initial result of the survey conducted on June 7, 2010 showed further inflation by 3.0 mm
Epicentral map as of June 18, 2010
TAAL EPICENTRAL MAP January-June 2010 LEGEND: Seismic Station Epicenters Prepared by: L. Bañes 06/20/10
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.
TAAL HAZARD WARNINGS BASED ON ALERT SIGNALS Expansion of risk areas depending on the magnitude of eruption. Alert Level 5 Total evacuation of the Volcano Island. Flank eruption – lakeshore barangays facing eruption sitel Eruption site: Main Crater – lakeshore barangays of Talisay, Tanauan, Agoncillo, Balete, San Nicolas and Laurel. Additional areas to be evacuated shall be determined based on the development of escalating activity and possible location of eruption site. Alert Level 4 Selective evacuation – women, children and elderly at the Volcano Island are advised to transfer to their relatives at the mainland. Alert Level 3 Main Crater, Daang Kastila and 1965-1977 Mt. Tabaro Eruption Site are off limits to the public. Alert Level 2 Main Crater is off limits to the public because sudden explosions may occur or toxic gases may accumulate. Volcano Island residents and visitors must be aware and vigilant of the volcano’s condition. Alert Level 1 ACTIVITIES ALERT LEVELS
RAISING/LOWERING OF ALERT LEVEL Slight seismic unrest Alert Level 1 23 November 2005 EVENT ALERT LEVEL DATE Increasing trends in monitoring parameters Alert Level 2 08 June 2010 Alert Level 0 30 June 2005 Series of volcanic earthquakes recorded; some felt at Intensity II-III at Volcano Island (Pira-piraso) Alert Level 1 (reiterated) 09 January 2005 Significant increase in daily seismic count Alert Level 1 29 October 2004 Advisory issued due to unfounded rumors of an impending eruption 29 September 2004 Alert Level 0 06 April 2000
Base surges (rapid horizontally moving mixture of volcanic debris and steam)
Seiche (lake water oscillation) and flooding
Ashfall and ballistic projectiles
Fissuring and subsidence
Hazards Associated with Eruption of Taal Volcano 1965 base surge 1969 lava flow Thermal area inside Main Crater
Impacts of Volcanic Hazards People who perished at the Volcano Island due to base surge Houses buried by ash during the 1965 eruption 1965 BASE SURGE TEPHRA FALL 1911 ground fissures Lemery, Batangas Daang Kastila fissure and landslide
VOLCANIC UNRESTS pH values ranged from 2.5 to 2.37; intense bubbling inside the MCL; lake temperature increased from 30 to 32 C; geysering at the NNE wall of MCL w/ temp. ranging from 97-100°C; more steaming vents were formed due to fissuring along the thermal area No significant inflation or deflation was measured Earthquake count up to 45 events a day. Quakes occasionally felt at volcano island (RF I-V). Epicenters at MCL to ENE of Taal. March to July 1991 Small bubbles observed at MCL; no significant change in lake temperature and pH. Slight inflation at MC and Mt. Tabaro Ave. of 6 events a day. Epicenters were scattered at MCL to NE of Taal. June to October 1989 Slight inflation (water tube tiltmeter) Several small amplitude (ave. of 2 mm) high frequency August (two-week period) 1988 pH w/in the baseline of 2.5-3 No significant change in lake temp No significant change, within noise level. Earthquakes felt at the SSW of Taal Lake 30 Oct. to 04 Nov. 1987 ALERT STATUS MAIN CRATER LAKE OBSERVATION GROUND DEFORMATION SEISMICITY DURATION YEAR
VOLCANIC UNRESTS No significant change in Main Crater Lake No significant change Seismic swarm; 59 located earthquakes; epicenters covered E and SE of MCL with depths of 2-5 km 19 July to 31 October 2000 Alert Level 3 (evacuation of women, children and the elderly from TVI) pH values of 2.18 to 2.20; intense bubbling at the E & NE sector of MCL; lake temp. gradually increased from 34 C to 39 C. Inflation of 16 cm at Daang Kastila and 9.8 cm at Calauit, SE of Taal. Two ground fissures formed at Calauit approx. 70 m apart (8.0 mm and 10 mm wide) Escalating increase; total of 1,550 events detected within 24 hours with several felt events (RF I-II); epicenters clustered at the E and SE sides of Taal with depths of <5 km. 11 March to 31 May 1994 Alert Level 2-3 (total evacuation of TVI ) Intense bubbling inside the MCL (detected by acoustic pressure sensor); abrupt increase of 2° in lake temp. as detected by telemetered sensor) Volcano island uplifted up to about 20 cm. Fissuring at Daang Kastila (5-50 mm wide & 20-400 m long; E-W trends and parallel to MC) and at Pira-piraso (2.6 mm wide and 1-2 m long – 5 fissures) Dramatic increase. Total of 2,550 events detected within 24 hours with several felt events but decreased to the baseline in less than two weeks. 14-28 February 1992 ALERT STATUS MAIN CRATER LAKE OBSERVATION GROUND DEFORMATION SEISMICITY DURATION YEAR
VOLCANIC UNRESTS Alert Level 1 November 17 - Geysering activity near the shoreline of Main Crater Lake; muddy water spewed 2-3 m high; sulfur stench also observed; MCL temp at 35°C; slight increase in bubbling activity the crater lake January – high level of seismicity; quakes clustered mainly at the East and Southeast sectors of Volcano Island covering the Main Crater and Calauit areas; depths of 2 - 4 km January, November 2006 Alert Level 1 reiterated in January; (AL lowered to 0 on 30 June 2005; AL 1 raised on 23 Nov. 2005) No significant change No significant change Series of volcanic earthquakes recorded; some felt at Intensity II-III at Volcano Island (Pira-piraso); epicenters located within Main Crater and SSE near Calauit; depths of less than 1.0 to 4.0 km Jan. to Feb.; 21 Nov 2005 Alert Level 1 (29 October 2004) No significant change in Main Crater Lake; steaming activity at the thermal areas inside the crater also remained weak Slight inflation of the volcanic edifice Significant increase in daily seismic count; large amplitude earthquakes; epicenters scattered within vicinity of Main Crater, near Binintiang Malaki (NNW) and near Calauit area (SSE); depths of less than 1.0 to 4.0 km beneath the volcano 23 Sept. to November 2004 ALERT STATUS MAIN CRATER LAKE OBSERVATION GROUND DEFORMATION SEISMICITY DURATION YEAR
VOLCANIC UNRESTS Advisory issued to notify concerned authorities and the public of the volcano’s unrest. Investigation conducted on 29 August 2008 showed that there are remarkable changes in the thermal areas at the northeastern and eastern sectors of Main Crater. Deflation – based on Jan, Feb., April & Sept. 2008 measurements Still inflated – based on 2004 measurements Volcanic quakes on 28 Aug. 2008 (12:33 PM and 12:46 PM) were felt at Int. II in Bgy. Pira-piraso with depths of 0.6 to 0.8 km.; epicenters were located at Daang Kastila. Another quake occurred on 30 Sept. 2008 felt at Pira-piraso, Alas-as & Banyaga (Int. I) with epicenters located 650 m west of the Island and depth of 1.7 km. August & Sept. 2008 Alert Level 1 June survey – inflation of the volcano edifice June – Increase in seismic activity; felt at Int. II-III at Pira-piraso; felt also at Calauit; depths of 2.8-3.4 km June 2007 ALERT STATUS MAIN CRATER LAKE OBSERVATION GROUND DEFORMATION SEISMICITY DURATION YEAR
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