Pyroclastic flows are among the most dangerous volcanic hazards on Earth. They can move at extremely high speeds and carry scorching material capable of devastating everything in their path. When Semeru produces large collapses like this, the flows often race down drainages on the volcano's flanks and can travel great distances from the summit.
Also known as Mahameru, Semeru is the highest volcano on Java and has remained one of Indonesia's most closely watched active volcanoes. This video captures a powerful and dangerous moment as a major pyroclastic flow surges from the volcano during the morning hours.
