Merapi is one of the most active volcanoes in Indonesia and has produced more pyroclastic flows than any other volcano in the world. It has been active for 10,000 years. Most eruptions of Merapi involve a collapse of the lava dome creating pyroclastic flows which travel
6 to 7 km from the summit. Some flows have traveled as far as 13 km from the summit, such as the deposit generated during the 1969 eruption. Velocity of these flows can reach up to 110 km/hour. A slow up flow of magma leads to an extrusion of viscous magma, which accumulate and construct a dome in the crater.
There has been no late eruption. Typically, small eruptions occur every two to three years, and larger ones every 10–15 years or so. Its volcanic devastation is claimed to have led to the collapse of the Hindu Kingdom of Mataram. Since 2006, there is increased seismicity at more regular intervals and a detected bulge in the volcano’s cone indicating that fresh eruptions were imminent. Authorities put the volcano’s neighboring villages on high alert and local residents prepared for a likely evacuation. The eruption in 2006 was followed with quakes of long-period oscillation rendering over 3,00,000 people homeless. Mount Merapi last erupted in 2010 that killed more than 200 people and thousand of people homelest.