Insights into the October-November 2010 Gunung Merapi eruption (Central Java, Indonesia) from the stratigraphy, volume and characteristics of its pyroclastic deposits

► The 2010 Merapi pyroclastic density currents were the largest ever reported. ► High-energy surges were decoupled from block-and-ash flows due to topography. ► Extreme hazard in the future relates to block-and-ash flows out beyond 10-15 km. ► Future decoupled surges could impact further populated areas in Kali Urang.