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hweejoo seahon 4 May 2010
Transcript of mt pinatubo
case study profile
Oceanic Philippines Plate and Continental Eurasian Plate convergence
lies on a destructive plate boundary
Active (dormant for 6 centuries before eruption in 1991)
Made up of alternating layers of lava and ash
Most notable incident June 1991 eruption
One of the largest 20th century eruptions
Top of the mountain was blown off
- Height decreased from 1,745 meters tall, down to 1485 meters high
(streams of gas and ash is violently ejected to a height of several miles)
- sent 18.14 million metric tons of sulfur dioxide
- 5 billion cubic meters of ash and pyroclastic debris
Pyroclastic flows sped down at 130km/h
H eavy rain brought by typhoon Yunya mixed with the ash and caused massive lahars
Climaxed with 9 hours of eruption on June 15, 1991
Resulted in 7.8 earthquake in northeast of Pinatubo region – depleted magma chambers to collapse
anticipated future events Future eruptions
Not likely in 100 to 400 years, even if it does, it would be much weaker that 1991 eruption.
processes The Eruptions
From June 7 to 12, the first magma reached the surface of Mount Pinatubo.
it had lost most of the gas contained in it on the way to the surface (like a bottle of soda pop gone flat)
the magma oozed out to form a lava dome but did not cause an explosive eruption.
soda what is the type of volcano/eruption
the volcano exploded in a cataclysmic
Local economic and social effects 800 people killed; 100,000 became homeless Damage mostly caused by lahars Deaths mostly due to rain-induced torrents of volcanic debris
severely hampered the economic developmentEconomic
of the surrounding areas Extensive damage to buildings and infrastruture cause billions of pesos to repair Global environmental effects sulfuric acidsulfate aerosolsdestruction of the ozone layer
Reduced global temperatures (max 0.73°C in Aug 1992)
Believed to have influenced 1993 floods along the Mississippi river,
Key figures and statistics The June 12-15, 1991, eruption of
1475m Pinatubo volcano,
located 100 kilometers northwest of Manila
in the Philippines, In total the Pinatubo eruption discharged 5 billion cubic meters of ash and pyroclastic debris (including 20 to 30 megatons of sulphur dioxide and aerosols) into the atmosphere via eruption columns which were 18km wide at the base and had heights of up to 30km. A large number of people had to be evacuated due to the erupting volcano, which had remained dormant for 6 decades. evacuate!!! this way>>>>>>> baggage what and how it happened shaking and squeezing the Earth's crust beneath the volcano. At Mount Pinatubo, this major earthquake caused a landslide, some local earthquakes, and a short-lived increase in steam emissions from a preexisting geothermal area, but otherwise the volcano seemed to be continuing its 500-year-old slumber undisturbed. In March and April 1991
molten rock (magma) rising toward the surface from more than 20 miles (32 kilometers) beneath Pinatubo
triggered small earthquakes and caused powerful steam explosions that blasted three craters on the north flank of the volcano. Prediction – What was done to predict the hazard event? What are some of the measures put in place to predict future events? Although it is possible to predict fairly accurately where volcanic eruptions are likely to
occur, it seems unlikely that there will ever be the ability to predict either the exact time or
scale of a specific event.
Knowledge of volcanic processes is incomplete, but forecasting has become more
accurate. Various physical processes can be monitored to signal an impending eruption,
along with knowledge of previous eruptions, however only around 20 of the world’s
volcanoes are being monitored. More basic observatory techniques are still useful, however,
to look out for early-warning signs.
As magma nears the surface and its pressure decreases, gases escape.
Sulphur dioxide is one of the main components of volcanic gases, and increasing amounts of it herald the arrival of increasing amounts of magma near the surface.
on May 13, 1991, an increasing amount of sulphur dioxide was released from Mount Pinatubo in the Philippines.
On May 28, just two weeks later, sulphur dioxide emissions had increased to 5,000 tonnes, ten times the earlier amount.
Mount Pinatubo later erupted on June 12, 1991.
Most scientists believe that this drop in gas levels is caused by the sealing of gas passages by hardened magma.
Such an event leads to increased pressure in the volcano's plumbing system and an increased chance of an explosive eruption.
Seismometers By May 1991, seismic data, coupled with increased sulfur dioxide released from the volcano,
suggested to scientists that new magma was filling the volcano's magma chambers.
Pinatubo's rapidly growing lava dome foretold an imminent large-scale eruption.
The combined evidence suggested to the vulcanologists that the volcano's magma chamber held a gas-charged, potentially explosive type of magma called andesite magma.
Based on the evidence, all the necessary preconditions appeared to be in place to create a catastrophic eruption. Prevention – Was the hazard preventable? If so what was done? 'Quite simply, very little can be done to actually prevent a volcanic eruption up to
now lava flows are the only primary hazard that man has attempted to control with any
success, through use of water sprays and/or explosions, to divert lava from its original course.'
Protection/Mitigation What were some of the measures put in place to mitigate the damages caused by the tectonic event? What kinds of technologies or systems were used to make people less vulnerable to the hazard? Preparedness – What are/were some of the prearranged measures to reduce loss of life and property? E.g. public education, drills, evacuation plans, emergency supplies I The People’s Organisation (PO) leaders were trained by the Non-governmental organization (NGO) to alert the residents to evacuate during the most critical time.
Messages from Philippine Institute of Volcanology and Seismology (PHIVOLCS) and the USGS (United States Geological Service) will be relayed through mass media, government and NGOs which have access to them.
Legal System National Disaster Coordinating Council (NDCC) shifts its disaster management approaches and strategies from reactive (emergency management, disaster response) to pro-active (disaster risk reduction/management). “Philippine Disaster Risk Reduction, Management and Recovery Act of 2009” develops policies and plans and the implementation of actions and measures pertaining to all aspects of disaster risk reduction, management and rezcovery, including good governance, risk assessment and early warning, knowledge building and awareness raising, reducing underlying risk factors, and preparedness for effective response and early recovery.
Strategic National Action Plan (SNAP) is a roadmap articulating priority programs and projects for the next ten years.
However, on June 12 (Philippine Independence Day), millions of cubic yards of gas-charged magma reached the surface and explodedin the reawakening volcano’s first spectacular eruption.
800 people killed; 100,000 became homeless The eruption of the volcano produced
a large number of micrometer-sized droplets of sulfuric acid
thrown into the stratosphere.
eventually spread out over the globe.
blocked energy coming from the Sun,
the Earth cooled off a little with about a half degree centigrade. before. after. Government of Philippines requested technical assistance from Japan to study mudflow and flood along Sacobia- Bamaban and Abacan river systems
Mt. Pinatubo Commission established the “Integrated Plan for Mt. Pinatubo Affected Area” to construct high dikes along the river banks.
Channel excavation was executed for a stretch of 12 km from downstream end of Bamaban River so as to achieve sufficient flow capacity.
Permeable spur dikes with reinforced concrete piles were provided at meandering portions to reduce velocity of river flow, protecting banks from soil erosion.
The National Disaster Coordinating Council (NDCC) recommends to the President of the Republic of the Philippines the declaration of State of Calamity in disaster-affected areas and the release of national calamity funds as needed.
Aspects of PHYSICAL GEOGRAPHY 2001 Edition by Marianne Chong B.A. (HONS) DIP ED
ira. isella.olivia.hweejoo . Gas emissions