SODIS is a simple technique to purify water using heat and ultraviolet rays from the sun. I discovered a modified version on Google+, posted by Rajini Rao of Johns Hopkins University (her G+ Profile: https://plus.google.com/u/0/114601143134471609087/posts), which included a link to this NIH report: (NIH report: http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.120-a305).
I've hiked around a few volcanoes—in Hawaii, Ecuador, Mexico—but the biggest chill I got was a vicarious one while interviewing volcanologist John Ewert for a children's book. He and his team climbed atop a very restless Mount Pinatubo in the Philippines in May 1991 to plant monitoring equipment. He told me they couldn't wait to get off that rock.
He and other observers smelled sulfur (the vents were belching gas), felt and heard periodic rumbling, and observed the strewn rocks and cracks of hiccups (a plugged vent exploding under pressure). The seismic recordings showed clear signs of big trouble ahead—which is what propelled the American team to join their Filipino counterparts.
John truly felt that his life was in danger.
What gave him—and me—chills, though, was his memory of the resident Aeta families, oblivious to that danger. Kids, women, men, elderly people—they stood watching the scientists with passive curiosity. John's voice rose and tensed as he told me how he tried to communicate what was about to happen to their mountain home. The language and cultural barriers proved too thick, and the scientists searched for a translator.