[quote]The supervolcano that lies beneath Yellowstone National Park in the US is far larger than was previously thought, scientists report. A study shows that the magma chamber is about 2.5 times bigger than earlier estimates suggested. A team found the cavern stretches for more than 90km (55 miles) and contains 200-600 cubic km of molten rock. The team found that the magma chamber was colossal. Reaching depths of between 2km and 15km (1 to 9 miles), the cavern was about 90km (55 miles) long and 30km (20 miles) wide. It pushed further into the north east of the park than other studies had previously shown, holding a mixture of solid and molten rock. “To our knowledge there has been nothing mapped of that size before,” added Dr Farrell. Some believe a massive eruption is overdue, estimating that Yellowstone’s volcano goes off every 700,000 years or so. But Prof Smith said more data was needed, because there had only been three major eruptions so far. These happened 2.1 million years ago, 1.3 million years ago and 640,000 years ago. “You can only use the time between eruptions (to work out the frequency), so in a sense you only have two numbers to get to that 700,000 year figure,” he explained.[/quote] So when that thing goes boom, even more of America will be gone.