Merapi volcano is one of the most active volcanoes in the world and during the last 3000 yrs, it has been more or less continuously in eruption. Merapi volcano is a stratovolcano with a south-west facing horseshoe-shaped summit crater filled by a lava dome. Its composition rangers from basalt to basaltic andesite (52 to 56% SiO2) and it has high Al2O3 (18.5 to 20.2% wt) and medium to high K2O …