Volcanic eruptions can drastically alter the geography of a region. Hot, liquid lava flowing downslope can force people living near volcanoes to flee their homes. Even more dangerous, however, are pyroclastic flows and lahars, in which volcanic rock fragments travel in fast-moving clouds and mudslides. This interactive resource adapted from the National Park Service explains why eruptions are explosive or effusive and details the many hazards associated with each type.
This media asset was adapted from Views of the National Parks: Volcanism Knowledge Center by the National Park Service.