The string of active volcanoes around the Pacific Ocean has lived up to its "Ring of Fire" name lately, sparking mass evacuations in Indonesia and Vanuatu and unsettling part of southwestern Japan. The 450 or so volcanoes that make up the ring outline where the massive Pacific Plate grinds against other plates that form the Earth's crust, creating a 40,000-kilometer (25,000-mile) -long zone prone to earthquakes and other seismic upheaval….