1. Recurring non-eruptive unrest at Taal (Philippines)
R.U. Solidum, E.P. Laguerta and Taal Monitoring Team
Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Volcano Observatory Best Practices Workshop:
Near-term Eruption Forecasting
11-15 September 2011

2. Introduction to PHIVOLCS
– major activities
Monitoring, warning and advisory services on volcanic and earthquake hazards, including tsunami
- national seismic network
- 6 volcano observatories
Hazard mapping and risk assessment services
Research and development
Disaster preparedness and risk mitigation services

3. Introduction to PHIVOLCS
– links (some)
Member of the Technical Working Group of the Disaster Risk Reduction and Management Councils (DRRMC) at National level and Regional to Provincial Level if present in area
Office of Civil Defense (OCD)
Local governments
Key government agencies – land use and development planning; local governance; education
Non-government organizations
Media

4. Tectonic Setting of the Philippines
~300 volcanoes:
23 active
26 potentially active

5. Taal Caldera Taal Caldera Volcano Island South China Sea Metro Manila
Tagaytay City
Main Crater Lake
Taal Caldera
Taal Lake
Volcano Island

6. Historical Eruptions at Volcano Island
33 eruptions since 1572
latest eruption: October 1977
Historical Eruption Sites
Main Crater (1572, 1591, , 1634, 1635, 1641, 1645, 1749, 1754, 1790, 1808, 1825, 1842, 1873, 1874, 1878, 1903, 1904, 1911)
Binintiang Malaki (1707, 1715)
Binintiang Munti (1709, 1729)
Pira-piraso (1731)
Off Calauit (1716)
Mt. Tabaro (1965, 1966, 1967, 1968, 1969, 1970, 1976, 1977)

7. Some Destructive eruptions of Taal
1754 (15 May-30 Nov) – Main Crater; Plinian; VEI 4; ?dead
1911 (27 Jan- 7 Feb) – Main Crater; Phreatic; VEI 3; 1335 dead
1965 (28 to 30 Sep) – Mt. Tabaro; Phreato-magmatic; VEI 4; ~200 dead
Taal base surge, 1965

8. Areas affected by base surges (1754)
Tagaytay City
Balayan
Calaca
Agoncillo
Lemery
Taal
Old Tanauan
Old Lipa
Mt. Batulao
Mt. Makulot
Old Taal
Areas affected by 1754 base surge
Data Sources:
Arboleda and Ruelo, (1986);
Torres, (1989) 20
kilometers
Eruption site

9. Areas affected by base surges (1911, 1965)4 km
Eruption site
1965 4 km
Eruption site
Areas affected by base surges
Data Sources:
Pratt (1911); Worcester (1912); Moore, Nakamura and Alcaraz, (1966); Moore (1967); Arboleda and Ruelo, (198x)

10. Base Surge Hazard Map At risk: ~5000 people on Volcano Island
at least 100,000 people around Taal Lake

12. Response Action Based on Alert Level
ALERT LEVELS
RESPONSE
Alert Level 1
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 2
Main Crater, Daang Kastila and Mt. Tabaro Eruption Site are off limits to the public.
Selective evacuation – women, children and elderly at the Volcano Island are advised to transfer to their relatives at the mainland.
Alert Level 3
Total evacuation of the Volcano Island.
Alert Level 4
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 5
Expansion of risk areas depending on the magnitude of eruption.

13. Taal Volcano Seismicity (1990-1999)
Pira-piraso Station

14. Taal Volcano Seismicity (2000-2011)

15. Description of some unrest in Taal
1991 Mar to Jul - increased seismicity up to 45 VT events/day; some felt at Intensities I-V; intense bubbling at Main Crater Lake (MCL); geysering at MCL; lake T increased by 2C
1992 Feb dramatic increase in seismicity with 2550 VT events within 24hrs, several were felt; decreased to baseline within 2 weeks; Volcano Island uplifted up to 20cm; fissuring at northeastern slopes; intense bubbling at MCL; lake T increased by 2C (Alert level 2 then 3 – evacuation of Volcano Island)
1994 Mar escalating increase in seismicity with 1550 VT events within 24hrs, several were felt at Intensities I-II; inflation of Volcano Island up to 16cm; fissuring at eastern slopes; intense bubbling at MCL; lake T increased by 5C (Alert level 3 – evacuation of Volcano Island)

16. Description of some unrest in Taal
SUMMARY OF SEISMIC SWARMS/UNRESTS AT TAAL VOLCANO
Description of some unrest in Taal
2010 Apr - June - increase in VT events, several were felt; slight inflation of Volcano Island; bubbling at MCL; lake T increased by 2-3C; increased steaming at Crater Lake (Alert level 2 - Main Crater off limits)
2011 Apr-May – increase in VT events, several felt at Intensities I-III; quakes from 4km to 1km beneath Volcano island; preceded by CO2 flux of 4600 t/d in late March, 4 times background measurement (Alert level 2 – Main Crater off limits)

17. Taal Volcano Seismicity (2005, 2008, 2010, 2011)

18. Precise Leveling at SE slope

19. CO2 Flux (2008-2011) CO2 flux from ITER (Spain)-PHIVOLS collaboration
Graph from Arpa et al, 2011

20. Communication of Forecast
(via fax, , web, phone)
NDRRMC
Head OP
VAAC
Tokyo
Darwin
PHIVOLCS HQ
OCD
National
NDRRMC
Members
PHIVOLCS
Observatory
OCD
Region
DRRMC
CAAP
National
Local
Met Office
National
Local
Province
DRRMC
Media
National
Media
Local
City/Town
DRRMC
CAAP – Civil Aviation Authority
of the Philippines
NDRRMC- National Disaster Risk
Reduction and Management
Council
OCD – Office of Civil Defense
OP- Office of the President
Village
DRRMC
Public

21. Awareness and Preparedness Activities
(Town of Laurel – 2008)

22. Awareness and Preparedness Activities
(Village of Bilibinwang, Agoncillo – 2008)
Village Captain
Civil Defense Director

23. Some on-going initiatives for Taal
Improvement of monitoring systems:
- seismic telemetry (currently 8 stations: 4SP, 4BB)
- deformation (currently 3cGPS, one e-tilt; precise leveling, EDM)
- electromagnetism
- gas geochemistry (CO2)
- Main Crater Lake observations (chemistry, T)
* With international partners from NIED and Japanese institutions (JICA-JST), EMSEV Group, ITER (Spain), others?
Awareness and preparedness at local level with province and OCD Region
Advocacy for appropriate land use and development
planning

24. PHIVOLCS Building, CP Garcia Ave. UP Campus, Diliman, Quezon City
THANK YOU!
PHIVOLCS Building, CP Garcia Ave.
UP Campus, Diliman, Quezon City
Tel ; Fax