Watch the history of volcano eruptions in the Philippines since 1900– in less than 30 seconds:
You just saw 96 volcano eruptions over the last 112 years– an average of 1 for every two years. The most active volcanoes are Mayon and Kanlaon– tied in first place with 24 eruptions each since 1900, followed by Bulusan and Taal. Together, these four volcanoes account for 71 eruptions or 3/4 of the total, with the rest divided among nine other volcanoes. (Eruption history data shown here are from the Smithsonian’s Global Volcanism Project records.)
The eruption of Mt. Pinatubo on June 1991 is by far the most cataclysmic in the country– it was the second-largest eruption of the century and its effects were felt worldwide. The eruption ejected some 10 cubic kilometers of material (imagine filling a box that is 2 km on each side!), giving it a Volcanic Explosivity Index (VEI) of 6. This is a hundred times more material than that for the next largest eruption, Taal in 1965, which had a VEI of 4. (Like the Richter magnitude scale for earthquakes, the VEI scale is logarithmic. Note, though, that in the video, the bubble sizes do not increase tenfold from one VEI magnitude to the next, but increase linearly with VEI.*)
The most recent eruption is of Mt. Bulusan in Sorsogon on February 2011, with a listed VEI of 2. According to various reports, the eruption affected 17 nearby towns with over 100,000 people– and over 2,000 people were called to evacuate.
I wonder how many Filipinos live around active volcanoes. Worldwide, the number is estimated to be 500 million. I visualize a map with circles around the most active volcanoes, sized according to the number of people who would be affected by an eruption of a certain VEI (say, from 0 to 4).
PHIVOLCS (Philippine Institute of Volcanology and Seismology) is responsible for monitoring volcano activity and issuing regular volcano bulletins. There are hazard maps for individual volcanoes like this one for Mt. Kanlaon. I’ll find out if they can make (or, have already made) the population figures available too.
* A VEI = 1 bubble is twice as big as a VEI = 0 one, a VEI = 2 bubble is three times as big, and so on. If the bubble sizes were shown accurately in tenfold size increases, the biggest eruptions will completely fill the screen– and well beyond!