The Toba depression in northern Sumatera is a complex structure, formed by repeated episodes of caldera subsidence and resurgence, strongly influenced by regional structure. The Toba depression, and the associated Toba Tuff, a widespread ignimbrite sheet which covers approximately 20.000km, are the result of three major eruptive events.
This thesis concered with volcanic hazard and risk. The study was addressed to analyzed and mapping of volcanic landform, mapping of volcanic hazard and volcanic risk zones of the area by yusing an aid of aerial photograph and other remote sensing image. Geomorphological approach have been used for analysing the landform wich is relatide to the volcanic hazard and its risk.
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 …
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