Alaska Volcano Observatory

Scientists have been watching two volcanoes on the Aleutian chain after noticing what they call a pattern of "seismic unrest" in the area.

The Alaska Volcano Observatory has been active since 1988. A lot of the tools it uses to monitor volcanoes in Alaska have changed since those early days.

When an ominous mushroom cloud of ash erupted from Mount Redoubt 31 years ago today, it was anyone’s guess how long the volcanic event would last.“The…