Philippine+arc

__What is an arc?__ A volcanic arc is a chain of volcanic islands or mountains formed as an oceanic tectonic plate subducts under another tectonic plate and produces magma at depth under the over-riding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone. There are two types of volcanic arcs: oceanic arcs (commonly called island arcs, a type of archipelago) and continental arcs. In the former, oceanic crust subducts beneath other oceanic crust on an adjacent plate- the Philippines is an example of this.It involves the Eurasion plate and the Philippine Sea plate.

__Location__ The Philippines lie in Southeast Asia in the western Pacific Ocean. Taiwan lies north across the Luzon Strait, to the west across the South China Sea sits Vietnam, with the Philippine Sea to the east. Made up of 7,107 islands, split into three regions Luzon, Visayas, and Mindanao. __Tectonic Activity__ The total land area is slightly more than 300,000 km2. Only approximately 1,000 of its islands are populated. Eleven islands make up 94 percent of the Philippine landmass. The islands originate from volcanic activity with there still 18 active volcanoes in the area which makes up part of the pacific ring of fire. The Philippines oceanic plate is subducting under the Eurasian plate at 16cm a year resulting in earthquakes and volcanic activity such as Mt Pinatubo in 1991. __Geology__ Due to the volcanic nature of the islands, mineral deposits are abundant. The country is estimated to have the second-largest gold deposits after South Africa and one of the largest copper deposits in the world. It is also rich in Nickel, Chromite, and Zinc with most of these mineral resources remaining largely untapped due to bad management and lack of development. Geothermal energy is another product of volcanic activity that the country has harnessed more successfully. The Philippines is the world's second-biggest geothermal producer behind the United States, with 18% of the country's electricity needs being met by geothermal power.




 * Case study - Mount Pinatubo - Eruption 1991 **
 * When **
 * June 15th - 1991


 * Where **
 * Island of Luzon in the Philippines – 55 miles northwest of the capital city Manila


 * Geology **
 * Mount Pinatubo is part of a chain of composite volcanoes along the Luzon arc on the west coast of the island.
 * The arc of volcanoes is due to the subduction of the Manila trench to the west


 * Effects **
 * Up to 800 people were killed.
 * 100,000 people became homeless.
 * Millions of tons of sulphur dioxide were discharged into the atmosphere – resulting in a decrease in the temperature worldwide for the next few years.
 * There was almost half a billion dollars in property and economic damages.
 * 4,979 homes destroyed and 70,257 homes were damaged.
 * The following year 3,281 homes were destroyed and 3,137 were damaged.
 * Damage following the Mount Pinatubo eruption was usually caused by lahars - rain-induced torrents of volcanic debris that killed people and animals and buried homes in the months after the eruption.
 * Another Mount Pinatubo eruption in August 1992 killed 72 people.


 * Events **
 * Eruption began in July 1990 - when a magnitude 7.8 earthquake occurred 62 miles northeast of the Pinatubo region, determined to be a result of the reawakening of Mount Pinatubo.
 * In mid-March 1991, villagers around Mount Pinatubo began feeling earthquakes and vulcanologists began to study the mountain.
 * On April 2, small explosions from vents dusted local villages with ash. The first evacuations of 5,000 people were ordered later that month.
 * Earthquakes and explosions continued.
 * On June 5, a Level 3 alert was issued for two weeks due to the possibility of a major eruption.
 * The extrusion of a lava dome on June 7 led to the issuance of a Level 5 alert on June 9, indicating an eruption in progress.
 * An evacuation area 12.4 miles away from the volcano was established and 25,000 people were evacuated.
 * On June 12, the danger radius was extended to 18.6 miles from the volcano resulting in the total evacuation of 58,000 people.
 * On June 15, the eruption of Mount Pinatubo began at 1:42 p.m. local time.

Case study -


 * Luzon** **Earthquake – 1991**


 * When**


 * The 1990 Luzon earthquake occurred on Monday, July 16, 1990, at 4:26 PM local time in the Philippines.


 * Where**
 * The densely populated island of Luzon was struck by an earthquake which meseaured 7.8 on the richter scale.


 * The earthquake epicenter was placed at 15° 42' N and 121° 7' E near the town of Rizal, Nueva Ecija, northeast of Cabanatuan City.


 * Effects**
 * An estimated 1,621 people were killed in the earthquake, most of the fatalities located in Central Luzon and the Cordillera region.


 * The earthquake caused damage within in an area of about 20,000 square kilometers, stretching from the mountains of the Cordillera Administrative Region and through the Central Luzon region.


 * The earthquake was strongly felt in Metropolitan Manila, leading to panic and stampedes and ultimately three deaths in the National Capital Region.


 * __Baguio__** **__City__****__, Benguet__**


 * Situated over 5000 feet above sea level, was among the areas most hardest hit by the Luzon earthquake.
 * The earthquake caused the collapse of 28 buildings, including hotels, factories, government and university buildings, as well as many private homes and establishments.
 * The quake destroyed electric, water and communication lines in the city.
 * Transport links such as roads were shut down due to landslides.
 * Baguio City was isolated from the rest of the Philippines for the first 48 hours after the quake.


 * __Cabanatuan__** **__City__**


 * Nueva Ecija, the tallest building in the city, a six-story concrete school building housing the Christian College of the Philippines, collapsed during the earthquake, which occurred during school hours killing around 154 people
 * Unlike in Baguio City, local and international journalists were able to arrive at Cabanatuan City within hours after the tremor.
 * The Christian College of the Philippines was the only building in Cabanatuan City that collapsed during the earthquake.
 * The city suffered about 363 casualties, (including 274 who were trapped ), with 154 of them dead.


 * __Dagupan__** **__City__****__, Pangasinan__**


 * In Dagupan City, about 90 buildings in the city were damaged, and about 20 collapsed.
 * Some structures sustained damage because liquefaction caused buildings to sink as much as 1 meter
 * The city suffered 64 casualties of which 47 survived and 17 died.

Patterns of damage
§ The earthquake caused different patterns of damage in different parts of Luzon Island. The mountain resort of Baguio was most severely affected because it had the highest population density and many tall concrete buildings, which were more susceptible to seismic damage. § All routes of communication, roads and airport access were cut off for many days, thereofre relief efforts were most diffilcut there. § Relief efforts were also hindered by daily drenching of cold rains. § Baguio has a large mining company and militray academy with experienced miners who started early rescue efforts. § Relief efforts in coastal areas were prompt and successful mainly due to the areas remaining accesible. § Relief effort changed from humans and injuries to public health concerns after 3 days eg there were many broken pipes, disrupted water systems, limited availbality of potable water and refugee camps had no toilet facilities. § There were early efforts to provide potable water to refugees through chlorine granules which was unsuccessful. § The next effort was using water from fire engines and getting the water cleaned before distribution.

Aftermath and reconstruction
§ Baguio City rebounded back as a tourist spot years after the earthquake. The land where the former Hyatt Regency Hotel stood is now the famous and well-visited SM Baguio. Holly Walls

· ** Taal Volcano ** is a complex volcano on the island of Luzon in the Philippines. It is situated between the towns of Talisay and San Nicolas in Batangas. · It consists of an island in Lake Taal, which is situated within a caldera formed by an earlier, very powerful eruption. It is located about 50 km from the capital, Manila. · It is one of the active volcanoes in the Philippines, all part of the Pacific ring of fire. · The volcano has erupted violently several times, causing loss of life in the populated areas surrounding the lake, the current death toll standing at around 5,000 to 6,000. · Because of its proximity to populated areas and eruptive history, the volcano has been designated a **Decade Volcano** worthy of close study to prevent future natural disasters. · It was thought to be named as "a volcano inside a volcano" because many believed that the lake that circles the volcano was once a crater or mouth of a volcano. · ** A level 1 Alert is in force for Taal which is giving signs of increased activity in June/July 2009 ** · There have been 33 recorded eruptions at Taal since 1572 · One of the more devastating eruptions occurred in 1911, which claimed more than a thousand lives. The deposits of that eruption consisted of a yellowish, fairly decomposed (non-juvenile) tephra with a high sulfur content. · The most recent period of activity lasted from 1965 to 1977, and was characterized by the interaction of magma with the lake water, which produced violent phreatic explosions · 965 eruption led to the recognition of base surge as a process in volcanic eruption. The eruption generated base surges and cold pyroclastic flows, which traveled several kilometers across Lake Taal, devastating villages on the lake shore and, killing about a hundred people · Eruptions in 1968 and 1969 were characterized partly by Strombolian activity and produced a massive lava flow that reached the shore of lake Taal. The 1977 eruption merely produced a small cinder cone within the main crater. · Shown signs of unrest since 1991, with strong seismic activity and ground fracturing events, as well as the formation of small mud pots and mud geysers on parts of the island. · The Philippine Institute of Volcanology and Seismology (PHILVOLCS) regularly issues notices and warnings about current activity at Taal, including ongoing seismic unrest. · 8 August 2008, notified "the public and concerned authorities" that the "Taal seismic network recorded ten (10) volcanic earthquakes from 5:30 A.M. to 3:00 P.M. today. Two (2) of these quakes that occurred at 12:33 and 12:46 P.M. were both felt at intensity II by residents at barangay Pira-piraso. These quakes were accompanied by rumbling sounds. The events were located northeast of the volcano island near Daang Kastila area with depths of approximately 0.6km (12:33 P.M.) and 0.8km (12:46 P.M.)" · 20 July 2009, National Disaster Coordinating Council (NDCC) NDCC executive officer Glenn Rabonza warned that although there were no volcanic quakes detected at Taal since the detection of nine volcanic quakes from June 13 to July 19, and there had been no steaming activity monitored since the last recorded on June 23
 * TAAL VOLCANO **
 * BASIC INFO **
 * RECENT ACTIVITY**
 * CURRENT ACTIVITY**