Temperatures are fluctuating wildly at one of two volcanoes Peter Jackson used as "Mount Doom" in his Lord of the Rings trilogy, and scientists believe an eruption at Mount Ruapehu on New Zealand's North Island could happen any day. Ruapehu is the country's largest active volcano and last erupted in 2007. If it does blow its top soon, it could ground flights and potentially disrupt the world premiere of The Hobbit: An Unexpected Journey in Wellington next week, International Business Times reports. (More New Zealand stories.)