Dormant volcanoes can become active quickly

Washington: Researchers suggest that the magma sitting 4-5 kilometers beneath the surface of Oregon`s Mount Hood has been stored in near-solid conditions for thousands of years, but the time it takes to liquefy and potentially erupt can be as little as a couple of months.

The key, scientists say, is to elevate the temperature of the rock to more than 750 degrees Celsius, which can happen when hot magma from deep within the Earth`s crust rises to the surface. Adam Kent, an Oregon State University geologist and co-author of the study, said that it is the mixing of the two types of magma that triggered Mount Hood`s last two eruptions - about 220 and 1,500 years ago. The scientists are interested in the temperature at which magma resides in the crust, they say, since it is likely to have important influence over the timing and types of eruptions that could occur. The hotter magma from down deep warms the cooler magma stored at 4-5 kilometers, making it possible for both magmas to mix and to be transported to the surface to eventually produce an eruption. The research has been published in the journal Nature.