How Much Worse Could That Eruption in the Philippines Get?

There's no end in sight to the hellish-looking eruption at Mount Mayon, the Filipino volcano that's been spewing a mix of ash and lava for two weeks. This week, after Mayon ratcheted things up with tall ash clouds and half-mile-high lava fountains, volcanologists placed it on alert level 4 out of 5--meaning a...