Pyroclastic flows run downhill along the Achupasal ravine on the side of the Tungurahua volcano 16 July, 2006 in southern Ecuador. Tungurahua erupted for a fourth day, burying thousands of farms in ash and threatening to "boil over" and dump lava on a nearby town, officials said.(AFP/Rodrigo Buendia)
Tania Martinez, left, cleans the roof of their house with her mother Silvia Ruiz after the Tungurahua volcano spewed ashes in the village of Pillate, near the Tungurahua volcano, Sunday, July 16, 2006. Some 3,700 people have been evacuated since Friday, when the volcano began expelling toxic gases and at least four lava flows, the first since it became active nearly seven years ago. (AP Photo/Cecilia Puebla.)
Red-hot lava cascades down the slopes of Mayon volcano, about 340 kilometers (212 miles) southeast of Manila, Philippines in its continuing 'mild and quiet' eruption late evening Monday July 17, 2006. The Philippine Institute of Volcanology and Seismology, PHIVOLCS, said the silent, steady flow of lava and debris on the 2,474-meter (8,118-foot) mountain has reached 800 meters (2,624 feet) down the summit but accompanying tremors have eased down to more than 100 overnight but still not ruling out an explosive eruption. (AP Photo/ Bullit Marquez)
Red-hot lava pours down the slopes of Mayon volcano, about 340 kilometers (212 miles) southeast of Manila, Philippines, accompanied by more tremors, for the fourth straight day Monday, July 17, 2006, indicating an explosive eruption may occur soon, scientists said. The Philippine Institute of Volcanology and Seismology, PHIVOLCS, said the silent, steady flow of lava and debris on the 2,474-meter (8,118-foot) mountain, famous for its near-perfect cone, has reached 800 meters (2,624 feet) down the summit since Friday. Scientists recorded 314 tremors in the past 24 hours, significantly higher than 111 tremors the previous day. (AP Photo/Bullit Marquez)