Newspinatubo

50 %
50 %
Information about Newspinatubo
Education

Published on February 24, 2014

Author: mbrmls

Source: slideshare.net

News: Botolan folk told: Watch out for typhoons Botolan folk told: Watch out for typhoons By Tonette Orejas CITY OF SAN FERNANDO, Pampanga—Filipino-American geologist Kelvin Rodolfo has asked his province mates in Botolan, Zambales to be constantly aware of typhoons and monsoon warnings from the weather bureau, urging them to map out evacuation plans to avoid floods and lahar. In an e-mail from Chicago, Rodolfo said the August 6 flashfloods, which displaced some 7,000 families in 10 villages in Botolan, happened because the Bucao River received runoff from a huge watershed that is still filled with lahar from Mt. Pinatubo’s 1991 eruptions. “All the runoff from rain [fall] on 270 square kilometers (sq km) on Pinatubo itself, plus 390 sq km from areas outside Pinatubo to the north, mainly the BalintawakCabatuan river sytem,” Rodolfo said of what drains to Bucao River before spilling to the South China Sea. Dr. Renato Solidum, chief of the Philippine Institute of Volcanology and Seismology (Phivolcs), said the flood was caused by heavy rains in the watershed of Bucao River. That watershed, he said, includes not only the slopes of Mt. Pinatubo but also the mountains west and north of the volcano. Strong current heavy with lahar and mud breached almost a kilometer of the Bucao dike, swamping 10 villages up to more than 1.52 meters of floodwater. The volcanic sediments that settled on the village of Carael, which were more than two meters high as of Sunday, caused the river to flow back to the other villages before heading out to the sea, said Alfredo Tolentino, director of the Department of Public Works and Highways in Central Luzon.

“People need to be constantly aware of typhoon and monsoon weather warnings from [the Philippine Atmospheric, Geophysical, and Astronomical Services Administration] and should have a standing plan as to high ground to go to, and a good route to it,” Rodolfo said. The study, “Two years of lahar on the western flank of Mt. Pinatubo: Initiation, flow processes, deposits, and attendant geomorphic and hydraulic changes,” provides scientific data and findings on what lies ahead of Botolan and other Zambales towns located on the western side of the volcano. The study, the most extensive of its kind for a Philippine volcano, was done by Rodolfo, Jess Umbal and Rosalito Alonso (University of Illinois at Chicago), Cristina Remotigue (National Institute of Geological Sciences, University of the Philippines Diliman), Ma. Lynn Paladio-Melosantos (Phivolcs), Jerry Salvador and Digna Evangelista (Mines and Geosciences Bureau), and Yvonne Miller (University of Geneva). The study said about two-thirds of the five to six cubic kilometers of rocks, ash, sand, mud, and gases that Pinatubo spewed out in 1991 settled on the western slopes. “[Lahar deposits] have filled channels almost to capacity, so future flows are expected to avulse out of the present lahar field along new routes,” it said. The sediments were “funneled principally” into the Bucao and Santo Tomas rivers. These had filled the channels, spilled out and buried villages and farms. “Considering the vast quantity of fresh pyroclastic debris, lahar, and excess sedimentation may continue for five to 10 years or longer,” it said. The Bucao River, with a total watershed of 659 sq km, drains the west and northwest of the volcano and its terrain. The river’s Pinatubo portion, spanning

270 sq km, is “by far the largest catchment basin on the volcano.” The southern part of the Bucao watershed, on the other hand, is drained by nine tributaries of the upper Balin Baquero River, which is joined by the Maraunot River downstream. Rodolfo said monsoon rains must be watched because 70 to 80 percent of at least 3,800 millimeters of annual rainfall in the province is delivered by the southwest monsoon (habagat) from June to September. Mt Pinatubo's brimming lake threatens thousands  19:00 25 July 2001 by Joanna Marchant Pinatubo, the Philippine volcano that erupted 10 years ago killing hundreds of people, may be about to wreak havoc of a different kind among the people living in its shadow. What's more, the authorities are doing little about it. Since the last eruption, the volcano's crater has been filling with rainwater and the water is now only a few metres from the rim. If heavy rains continue the rim could be breached, and a wave of water and volcanic debris sweep through towns and villages below, say geologists. Kelvin Rodolfo, an expert on Mount Pinatubo from the University of Illinois in Chicago, and Rosalito Alonso, head of geology research with the British aid charity Oxfam, have been trying in vain to persuade the Philippine authorities to prepare for such a flood. "We can't ignore the fact that we have several hundred million cubic metres of water sitting up there, and a town down here," says Alonso. "Somebody has got to say something," says Rodolfo. Overspill Pinatubo's 1991 eruption was one of the most violent of the 20th century. Hundreds of thousands had to flee their homes as huge swathes of the Philippines were turned into a grey desert. Since then, many local people have returned to their homes. Few, however, know about the crater lake that now holds around 250 million cubic metres of water. With a local annual rainfall of more than 3.5 metres and the funnel effect of the crater, the water level has been rising by up to 10 metres each year. This year has been particularly wet, and since the rainy season began in June the water level has been rising by up to a metre each week. The last time Rodolfo and Alonso flew over the lake in a military helicopter, they estimated that the water was only four metres from the lowest point of the crater wall, a V-shaped cleft called the Maraunot notch. The geologists predict that when the water reaches the notch it will spill over the edge into the Maraunot river. Once the water starts to spill, they fear the crater wall could give way.

Crumbly top Chris Newhall of the University of Washington in Seattle led a field trip to Pinatubo in May. His group found that at least the top 10 metres of crater wall is made of volcanic "breccia" - angular fragments of sand and rock deposited by the last eruption. If water starts running over the top, Newhall says, the breccia will crumble. "When the water reaches the top it could begin eroding downward until it hits rock that is solid," he says. Rodolfo and Alonso estimate that if the notch eroded down 10 metres, 30 million cubic metres of water would spill out. The water would probably mix with loose volcanic sediment on the way, hugely increasing its volume and creating a cement-like mixture knows as a "lahar". Rodolfo has seen fast-flowing lahars in action before. "It is a horrendous sight - horrifying and exceedingly beautiful." After hearing about Newhall's work, and realising that nothing was being done, Lan Mercado, Oxfam's representative in the Philippines, asked Rodolfo and Alonso to identify the risks to local people. There are two hamlets built on the riverbanks and at the bottom of the slopes is the town of Botolan, with 48,000 inhabitants. At the rate the water is rising, the geologists estimate that the crater wall could give way in less than a month, letting a lahar plough straight through Botolan. "The town would have less than two hours' warning. There is no plan. We want people to know about it and be prepared," says Alonso. Watch and wait National authorities have been slow to respond to Oxfam's warnings. Last month, Rey Punongbayan, director of the Philippines Volcanology and Seismology Agency commissioned a report into the lake by Masao Chida, an engineer from the Japanese consultancy firm Nippon Koei. Chida visited the crater by helicopter and concluded that there was little likelihood of a serious breach. "We will just watch what happens this rainy season," says Florente Soriquez of the Department of Public Works and Highways. Engineering solutions to the threat include reinforcing the notch, or boring a tunnel into the crater to drain the lake. But the government says it is too late for such action now the rainy season has started. Rodolfo and Alonso believe this complacency could be disastrous and are now working with Oxfam to reach local agencies and people directly. They are urging people to find safe buildings, arrange shelter and supplies, and monitor the rivers for rising water levels. Oxfam's actions have alarmed the government. Oxfam "should not announce their findings in public", says Punongbayan. "It may make people nervous." But Mercado counters: "It's raining cats and dogs out here and the crater is filling up fast

Add a comment

Related presentations

Related pages

Mount Pinatubo Eruption (June 1991) - About Geography ...

The 1991 eruption of Mount Pinatubo in the Philippines killed hundreds, damaged thousands of homes, and had negative effects on the whole planet.
Read more

Pinatubo Volcano, Luzon Island (Philippines) - facts ...

Pinatubo Volcano, Luzon Island (Philippines) - facts & information / VolcanoDiscovery/ VolcanoDiscovery
Read more

Articles about Mount Pinatubo - latimes

Mount Pinatubo News. Find breaking news, commentary, and archival information about Mount Pinatubo From The latimes
Read more

Pinatubo | WIRED

Pinatubo subscribe. Open Search Field. Search. Business; culture; Design; Gear; Science; Security; transportation; ... Skip To: Latest News. pinatubo ...
Read more

BBC Bitesize - GCSE Geography - Powerful volcanic eruptions

Powerful volcanic eruptions. Duration 02:31. You need to have JavaScript enabled to view this video clip. Description. An animation of the Mount Pinatubo ...
Read more

Pinatubo: Why the Biggest Volcanic Eruption Wasn't the ...

If you'd been on the Philippines island of Luzon on June 15, 1991, you'd have been forgiven for thinking that the world was ending. Typhoon Yunya was ...
Read more

Featured Articles about Mount Pinatubo - Page 3 - latimes

Featured Mount Pinatubo News. Find breaking news, commentary, and archival information about Mount Pinatubo From The latimes (Page 3 of 5)
Read more

Pinatubo volcano eruptions / VolcanoDiscovery

Pinatubo Volcano, Luzon Island (Philippines) - facts & information / VolcanoDiscovery/ VolcanoDiscovery
Read more

Supervolcano eruption mystery solved - BBC News

Supervolcano eruption mystery solved. By James Morgan Science reporter, BBC News. 6 January 2014. From the section Science & Environment; Image caption If ...
Read more