Chilean Lake May be the Site of Mega-Eruption

An odd-shaped Chilean lake in the Andes Mountains may not look like your typical volcano, but it may be the site of a future mega-eruption, according to a recent study.

Laguna del Maule has erupted 36 times during the last 25,000 years, and activity happening just three miles under it suggests that it may soon be ready to blow again. The rate of uplift is among the highest ever observed by satellite measurement for a volcano that is not actively erupting - rising 10 inches annually for the last seven years.

"We've always been looking at these mega-eruptions in the rear-view mirror. We look at the lava, dust and ash, and try to understand what happened before the eruption. Since these huge eruptions are rare, that's usually our only option," lead author Brad Singer said in a statement.

"But we look at the steady uplift at Laguna del Maule, which has a history of regular eruptions, combined with changes in gravity, electrical conductivity and swarms of earthquakes, and we suspect that conditions necessary to trigger another eruption are gathering force," he added.

Due to erosion caused by heavy rain and snow, this lake looks nothing like the classic, cone-shaped volcano people usually picture. But don't let that fool you, there is a restless magma reservoir lurking below, composed of the most explosive type of molten rock on the planet.

Referred to as rhyolite, this fiery magma often explodes into vast quantities of ash that can form deposits hundreds of yards deep, followed by magma tens of yards tall oozing for more than a mile from the eruption site. This could result in an eruption comparable to Mount St. Helens, or bigger.

"We know that over the past million years or so, several eruptions at Laguna del Maule or nearby volcanoes have been more than 100 times larger than Mount St. Helens," Singer said. "Those are rare, but they are possible."

Such an explosion has lasting effects, among them changing the weather, disrupting local ecosystems and damaging the economy.

To find out what Laguna del Maule holds in store, as many as 50 seismometers will eventually be placed above and around the site to create a 3-D image of Earth's crust. Singer is also conducting a five-year study to model the magma below to determine when a future eruption may occur. But one thing's for sure, he said, "the surface cannot continue rising indefinitely."

The findings were published in the journal GSA Today.

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