Five climbers were killed and seven were injured in the Philippines yesterday (May 6) when the volcano they were scaling suddenly exploded, according to news reports. The group was atop the turbulent Mayon volcano, an 8,077-foot-tall (2,462 meters) stratovolcano, which last erupted in 2010. There were no signs of an imminent eruption before the climb, according to Philippine Institute of Volcanology and Seismology (PHILVOCS), which monitors volcanic hazards. In fact, the volcano still remains at a zero alert level, with no earthquake activity.
The killer burst was likely a relatively unpredictable phreatic explosion, from water seeping into the volcano's magma chamber, then blasting out as steam (think of a geyser). The flare-up also sent a small ash column 1,600 feet (500 m) into the air, PHILVOCS said. The deaths highlight the danger of hiking and working on active volcanoes, whether for tourists or for scientists, volcanologist Erik Klemetti wrote on Wired's Eruptions blog. After a string of similar climbing fatalaties in the 1990s, the International Association of Volcanology and Chemistry of the Earth's Interior developed safety guidelines for researchers and the public working on active volcanoes.
Read more: Eruptions blog