Merapi volcano (Central Java, Indonesia) is one on the most active strato-volcanoes in the world, located in a very densely populated rural area and at 25 km north of the historical city of Yogyakarta. Before 2010, known eruptions implied the growth and collapse of domes, with generation of deadly “nuées ardentes”. These eruptions have been studied in detail by many research groups in the world, with different techniques and methods, including ground and space observations, numerical modelling, and sociological approaches. The October-November 2010 eruption was very different in many aspects. According to seismic records, the energy released during that eruption was 100 times larger than that from any previously monitored eruptions. Space observations of ground deformations by means of high resolution SAR data has been available for the first time at near real-time basis thanks to the quick response from Space Agencies and GMES system. In addition to the usual proximal hazards, this eruption also produced significant ash emissions, with a more explosive mode of eruption, that resulted in widespread ash fall on communities and disruptions to air traffic in the region. This large amount of deposits increased dramatically the threat of number and size of lahars. This session is dedicated to highlighting similarities and differences between previous eruptions and the 2010 eruption. Understanding the possible link between volcanic and tectonic activity at various scales will also be of particular interest. We would like to make a state-of-the-art of our scientific knowledge on Merapi volcano, with emphasis in the fields of geology, geochemistry, geophysics, tectonics, but also including risk analysis and socio-economics. We are seeking to gather researchers who worked in the past and at present at Merapi volcano and who are willing to collaborate in future studies to make the link between various hazards and risks. Despite a clear focus of this session on Merapi volcano, we also very welcome studies of other volcanoes showing a similar eruptive behaviour.