Which '3 Little Pigs' House Would Survive a Volcano?
A spectacular volcanic eruption in Indonesia has killed three people and forced mass evacuations, disrupting long-haul flights and closing international airports on Friday. Mount Kelud, considered one of the most dangerous volcanoes on the main island of Java, spewed red-hot ash and rocks high into the air late Thursday night just hours after its alert status was raised.Learn more about volcanoes in our Volcano Explorer
Villagers in eastern Java described the terror of volcanic materials raining down on their homes, while AFP correspondents at the scene saw residents covered in grey dust fleeing in cars and on motorbikes towards evacuation centers. Some of Java's Buddhist temples, such as Prambanan Temple, above, were closed as volcanic ash from Mount Kelud rained down on them.
U.S. Geological Survey
The 1,731-meter (5,712-foot) Mount Kelud has claimed more than 15,000 lives since 1500, including around 10,000 deaths in a massive eruption in 1568. It is one of 130 active volcanoes in Indonesia, which sits on the Pacific Ring of Fire, a belt of seismic activity running around the basin of the Pacific Ocean. Earlier this month, another volcano, Mount Sinabung on western Sumatra island, unleashed an enormous eruption that left at least 16 dead and has been erupting almost daily since September.
Some 200,000 people were ordered to evacuate, though some families ignored the orders and others have returned home, with just over 75,000 now in temporary shelters, National Disaster Mitigation Agency Spokesman Sutopo Purwo Nugroho told AFP.
Nugroho confirmed that ash and pumice were still raining down on villages within a radius of 15 kilometers (9 miles) from the volcano on Friday, but said that some activities were resuming "as normal."
The ash has blanketed eastern Javanese cities, forcing seven airports to close, including those in Surabaya, Yogyakarta, Solo, Semarang and Bandung, which serve international flights, officials said, while grounded planes were seen covered in the dust. "All flights to those airports have been cancelled, and other flights, including some between Australia and Indonesia, have been rerouted," Transport Ministry director general of aviation Herry Bakti said, adding it was "too dangerous to fly" near the plume.
The relative strengths of building materials in a wolf-induced windstorm are clear, thanks to the classic story of the Three Little Pigs. But how do basic buildings hold up in a more complex natural hazard such as a volcano? A new study assesses the various threats to structures during an eruption, hoping to help communities better understand their vulnerabilities.
Eruptions of explosive volcanoes, such as those that dot the Pacific Rim, feature many more hazards than lava alone. Falling ash and hot flying rock can overload or puncture roofs, while scalding flows of ash, debris or mud can pound at walls and pour through doors and windows. This is all assuming, of course, that the building under assault hasn’t already been leveled by a volcanic earthquake or a lateral blast, or buried under a landslide. Even the best-built homes face serious challenges in volcanic hazard zones.
An international team assessing volcanic risks visited the areas surrounding two active volcanoes: Kanlaon volcano in the Philippines and Fogo volcano in Cape Verde. Researchers found that most dwellings near Fogo were constructed with masonry and featured reinforced concrete roofs. Dwellings near Kanalon included some built with masonry, some built with timbers and still others built from woven palm fronds with corrugated steel as a common roofing material.
Unreinforced masonry structures with concrete roofs may be vulnerable to volcanic earthquakes, the researchers report in the Journal of Volcanology and Geothermal Research, which published their results. Timber structures may resist seismic shaking better, but are more vulnerable to ash and debris falling from the sky or flowing along the ground. Masonry structures, on the other hand, may bear ash falls just fine.