Indonesia’s Mount Merapi Volcano

A lava dome is forming rapidly at the volcano’s peak. When it collapses, the most powerful stage of the eruption is expected to take place.  (Blontank Poer / Getty Images)

Its last eruption, in 1994, left 66 dead. Another in 1930 killed 1,300 people.  (Blontank Poer / Getty Images)

Mount Merapi spewed deadly clouds, known by locals as “wedhus gembel” (shaggy goat) in May 2006. The clouds consist of gases, ash and dust that reach temperatures of up to 430 degrees Fahrenheit. A 1994 eruption left 66 dead. Another in 1930 killed 1,300 people.   (Blontank Poer / Getty Images)

Searing heat clouds belched out of the volcano early on Wednesday, May 17th, as scientists anxiously waited for a major eruption.  (Jewel Samad / AFP/Getty Images)

The alert remained at its highest level Wednesday for the 3,000-meter (9,800-foot) mountain at the heart of Java island. Scientists cautioned that a lull in activity did not mean the danger was over.  (Ed Wray / AP)