In all, Indonesia plays host to some 129 active volcanoes, forming one of the more spectacular corners of the Pacific Ring of Fire, a global system of tectonic faults resulting in dramatically increased earthquake and volcano activity.

People of the region have long lived side by side with volcanoes. The nearby island of Java, for instance, has experienced an estimated 140,000 volcano-related deaths in the last 500 years. (See NASA satellite images of Java's Mount Merapi erupting.)

Indonesian culture and religion revolves around this constant threat, and even now, locals balance the advice of mystic "gatekeepers" with warnings from scientifically trained volcanologists. (Read more in National Geographic: Living With Volcanoes.)

This eruption, although certainly breathtaking, did not cause authorities to recommend evacuation.