Volcano Journal Entry

Scientists Keep Watch on Galeras (November 16, 2009)

Scientist's are watching Colombia's Galeras volcano very closely these days. The volcano's alert level was raised to code "orange," the second highest level, signaling a larger eruption may occur within days or weeks. This week, the volcano's summit shook with an increase of earthquakes, a sign that magma is moving inside the volcano. A few weeks ago, the volcano exploded with thick clouds of ash and hot, glowing lava.

Galeras is found in southwestern Colombia, 335 miles (540 km) from the nation's capital Bogota. Scientists consider it one of the most dangerous volcanoes in South America. The volcano woke up from dormancy in 1989 and has been active on and off ever since.

The volcano's deadliest eruption since waking up was in 1993, when nine people were killed after it exploded suddenly. Five of the victims were scientists who had gone down into the volcano's crater to sample gases just before it exploded. More recent eruptions have forced thousands of people to flee their homes to escape clouds of ash.

The Nazca plate subducts or dives under the South American plate all along the Pacific coast of South America. Crust from the subducting plate melts and forms magma as it slides into the hot upper mantle. Eventually, some of the magma finds its way back to the surface through the continent's many volcanoes.