Volcanoes across the country are beginning to wake up and erupt, and no one has a good explanation for why it's happening.

With a competent guide, active volcano treks are both safe and worth the climb. Here are some of the tallest active volcanoes ...

Volcanoes are rumbling as scientists monitor earthquakes at Washington's Mount Rainier and Alaska's Iliamna volcano.

The Hawaiian Volcano Observatory, part of the U.S. Geological Survey, defines an active volcano as one that has erupted within the past 10,000 years.

It has been an active volcano for more than a millennium. In December 1989, it erupted for the third time in the 20th century, spewing volcanic ash to an altitude of 45,000 feet.

The Hawaiian Volcano Observatory, part of the U.S. Geological Survey, defines an active volcano as one that has erupted within the past 10,000 years.