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Pyroclastic Flow

Pyroclastic Flow. http://www.youtube.com/watch?v=Cvjwt9nnwXY&feature=related http://www.youtube.com/watch?v=WxlRpuTed6g&feature=related. Effects of the Mt Pinatubo Eruption in 1991. http://www.youtube.com/watch?v=t8dopMdq6Qk&feature=related. Geographic Location.

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Pyroclastic Flow

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  1. Pyroclastic Flow http://www.youtube.com/watch?v=Cvjwt9nnwXY&feature=related http://www.youtube.com/watch?v=WxlRpuTed6g&feature=related

  2. Effects of the Mt Pinatubo Eruption in 1991 http://www.youtube.com/watch?v=t8dopMdq6Qk&feature=related

  3. Geographic Location • Southeast Asia - Northwest of Australia, • East of Vietnam, and southwest of Japan. • Bordered by the Philippine Sea, and the South China Sea

  4. Natural Hazard Exposure The Philippines are unusually susceptible to natural hazards -- the junction of several tectonic plate boundaries -- frequent tropical cyclones

  5. Location of Mt Pinatubo • 15°13' N, 120°35' E (Island of Luzon) • intersection of the borders of the provinces of Zambales, Tarlac, and Pampanga. • Elevation: 5248ft (1600m)-9/24/2001 • 1,745 meters before the June 15, 1991 eruption and 1,485 meters after (caldera rim high point)

  6. Volcanic Hazards of the Philippines

  7. Tectonic Setting • The Philippines lie near the convergence of several tectonic plates, the Indo-Australian, Philippine, and the Pacific plates. • Oceanic to oceanic plate convergence creates Island Arc formations of volcanic islands.

  8. Type of Volcano & Magma • Composite Volcano • Andesitic Magma with high water content

  9. Formation Of Mt. Pinatubo • The subduction volcano is formed by the Eurasian plate sliding under the Philippine Plate along the Manila Trench.

  10. Sequence of Events • 3rd August 1990Loud rumbling heard, a landslide near the summit, and steaming ground. First volcanic activity in 500 years. • August 1990Five earthquakes near Pinatubo. • 2nd April 1991 Steam and ash exploded from a 1.5 km long fissure high on the northern slopes of Pinatubo. Smell of sulfur and ash fell 10 km away. • 3rd April 1991200 small earthquakes registered at the volcano. • 23rd April 1991US Geological Survey arrived with monitoring equipment. • 26th April 1991Monitoring station set up at Clark Air Base 25 km to the east of the volcano.

  11. Fig. 7-48, p.179

  12. One of the early explosive eruptions at Pinatubo after the April 1991 onset of ash eruptions

  13. Monitoring • A series of small steam-blast explosions in early April, 1991, prompts scientists from PHIVOLCS to begin on-site monitoring and declare a 10-kilometer (6-mile) danger zone around the volcano. • USGS scientists from the Volcano Disaster Assistance Program, bring specially designed, portable instruments to set up monitoring networks. • The USGS studies the volcano's past eruptive history. Data indicates a huge eruption is imminent. • Warnings were issued enabling civil and military authorities to arrange the evacuation.

  14. Evacuation • Daily alerts issued stating the alert level and associated danger area. • Information announced in major national and local newspapers, radio and television stations, nongovernmental organizations (NGOs), and directly to nearby inhabitants. • Formal evacuations were ordered on 7 April. • Over 200,000 evacuated to lowlands • Population temporarily relocated to Manila and Quezon City, with some 30,000 using the Amoranto Stadium in Quezon City as a refugee camp.

  15. Evacuation Zone

  16. The Main Eruption15th June 1991 • 3:39 pm the main eruption begins. • Columns of ash, gas and steam rise 34km high and traveled 400km. • Evacuation area increased to 40km radius. • 90 percent of the total material for the eruption was expelled from the volcano in 9 hours. • Typhoon Diding passes 100km northeast of Pinatubo, bringing heavy rainfall. • Lahars raged down the mountain at 30 km/hr. • At 4:30 pm the summit of Pinatubo begins to sink. • Eruption stops at 10:340 pm.

  17. Snow-like ashfall caused by heavy rain mixing with ash columns

  18. Fig. 6-37, p.144

  19. Fig. 6-38, p.144

  20. Fig. 6-32, p.142

  21. Fig. 6-19, p.137

  22. Areas of lahars after eruption

  23. Before and after the eruption: a river valley filled in by pyroclastic flow deposits

  24. Casualties & Damage • More than 700 people killed. • 8,000 houses destroyed and 75,000 houses damaged. • Damage estimated at $450 million dollars. • Fallout affected a total area of 340,000 km2 • Rice paddies and sugar cane fields buried • Forests buried under 50-200m deep ash and pumice. • Ash and 20 mil tons of SO2 gas entered the stratosphere and circled the earth within 12 months, reducing global temperatures by 0.5°C. • Over 2 million people were affected by the eruption. • Summit of the volcano reduce by 260m. • A huge caldera formed 2.5 km across. • In spite of damage and lives lost, the biggest volcanic disaster of the 20th century was minimized due to good communication and monitoring.

  25. Table 3. Percent of Families Affected by Lahar and flood combined Total 100% ( 33,400 (1991) and 164,191 (1992) families)

  26. Additional Effects • Since the 1991 eruption, lahars have destroyed the homes of more than 100,000 people. • One lake on the volcano's east flank, has formed and broken out three times (1991, 1992, and 1994), creating lahars that have killed dozens of people. • New towns have now been built on high ground.

  27. Global Impact • The powerful eruption injected a significant amount of aerosol and dust into the stratosphere. • The results: • Reduction in sunlight reaching the earth’s atmosphere by 5% • N. Hemisphere’s average temperature was decreased by .9-1.1F

  28. The absorption of radiation by aerosol increased the stratosphere’s temperature. • The material lasted in the clouds for 3 years. • Significant effect of ozone deterioration rate.

  29. Lake formation in caldera after eruption

  30. Mitigation • U.S.G.S. forecast resulted in the saving of at least 5,000 lives and at least $250 million in property. • A least another $50 to $100 million in damage to aircraft saved by avoiding ash clouds. • PHIVOLCS and USGS scientists spent less than $1.5 million responding and forecasting the eruption. • Philippine, U.S., and nongovernmental organizations spent about $40 million to evacuate, house, and feed local residents and American military personnel

  31. Lahar Monitoring Since June 1991 lahar monitoring systems have been in operation. • Radio-telemetric rain gauges. • Acoustic flow monitors on stream banks detect ground vibration as lahars pass. • Manned lookout stations to confirm lahars flows. • System has enabled warnings to be sounded for most lahars, saving hundreds of lives.

  32. Risk Management • The disaster management system is based on a government decree that has not been updated in 20 years. • Frequent natural disasters have hindered the Government’s efforts to reduce the incidence of poverty and reduce the number of people and assets vulnerable. • Disaster management systems mostly rely on a response or reactive approach, in contrast to a more effective proactive approach, in which disasters are avoided, by appropriate land-use planning, construction and other pre-event measures which avoid the creation of disaster-prone conditions.

  33. Conclusion Risk Identification: High quality, comprehensive hazard and vulnerability maps for major natural hazards need to be produced or updated. Improved knowledge base and understanding of the scale of impact and forms of vulnerability. Risk Reduction: Measures need to be taken to prevent, mitigate and reduce the inherent risks. Risk Sharing/Financing: The Government of the Philippines and individual households currently bear the majority of costs. More effective options for financing disaster risk and relieving the burden of disasters should come from the public sector, including the idea of a catastrophe insurance pool, and/or contingent credit facilities.

  34. References Natural Disaster Risk Management In The Philippines: Enhancing Poverty Alleviation Through Disaster Reduction The World Bank National Disaster Coordinating Council East Asia and Pacific Region Republic of the Philippines Rural Development Benefits of Volcano Monitoring Far Outweigh Costs–The Case of Mount Pinatubo Chris Newhall, James W. Hendley II, and Peter H. Stauffer U.S. Geological Survey Fact Sheet 115-97Online Version 1.1http://pubs.usgs.gov/fs/1997/fs115-97/ The Mount Pinatubo Disaster and the People of Central LuzonBy Cynthia Banzon Bautista, Department of Sociology and Center for Integrative and Development Studies, University of the Philippines, Diliman, Quezon City, Philippines.http://pubs.usgs.gov/pinatubo/cbautist/ Socioeconomic Impacts of the Mount Pinatubo Eruption By Remigio A. Mercado,1 Jay Bertram T. Lacsamana,1 and Greg L. Pineda11 National Economic and Development Authority, Region III, San Fernando, Pampanga, Philippines. http://pubs.usgs.gov/pinatubo/mercado/ U.S. Geological Survey Fact Sheet 114-97 Online Version 1.1 Lahars of Mount Pinatubo, Philippines http://pubs.usgs.gov/fs/1997/fs114-97/ Mt. Pinatubo Milton J. Sweet http://www.utdallas.edu/~msweet/e&v1.html

  35. Other photos

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