VDAP Responses at Merapi in Indonesia
A successful crisis response by a first-class volcano hazards team (Indonesias CVGHM)
Merapi, one of the worlds most hazardous volcanoes, is located in Indonesia, the most volcanically active country on Earth. In 2006, VDAP sent a four-person team to assist the Indonesian Center for Volcanology and Geologic Hazard Mitigation (CVGHM) during the eruption of Merapi, which threatens more a million people living in the metropolitan Yogyakarta region. The VDAP team provided a new seismic processing system, remote sensing data, and monitoring equipment that enabled more rapid hazard analyses by CVGHM. They also worked with CVGHM scientists to develop a probabilistic event tree for use in informing decisions regarding the likely course of the eruption and requirements for evacuations.
The principal hazard at Merapi is pyroclastic flows. Pyroclastic flows are fast moving, >500°C hot ash hurricanes. The geologic history of the area shows that the magnitude of eruptions and the extent of impacts have ranged widely in the past. Another big concern in 2006 was the possibility of a summit collapse. In 1930, such a collapse devastated areas out to more than 10 km from the summit and killed 1400 people.
On 25 April 2006, a lava spine emerged. Deformation of the summit region stopped as the pressure was relieved and the threat of a 1930type collapse was reduced. However, the threat then shifted to the possibility of a collapse of the new lava dome to produce pyroclastic flows in areas that had not been subject to this hazard for decades. CVGHM effectively anticipated such collapses and their impacts, producing a hazard map showing potential areas at risk and using monitoring data and an alerting system to warn at-risk populations. These preparations resulted in evacuations of up to 40,000 and saved lives when collapses of the lava dome sent pyroclastic flows down drainages previously assumed by the inhabitants to be safe.
This successful volcano response was largely overshadowed on 27 May, when a M6.3 earthquake rocked Yogykarta, ~20 km from the volcano, killing 5700, injuring 40,000 and displacing 500,000.
Again in 2010 and at the request of the President of Indonesia, a VDAP team was deployed to assist CVGHM in their response to the largest eruption of Merapi in the past 100 years. VDAP organized an unparalleled remote sensing response, which utilized satellite radar data to see through clouds that obscured the volcano, which took place during the rainy season in late October and early November of 2010. VDAP served as manager for the International Charter for Space and Major Disasters. Building on more than 20 years of collaboration with CVGHM and its predecessor organization, the Volcanological Survey of Indonesia (VSI), VDAP scientists were able to effectively deliver near-real time analyses of changes at the volcanos summit directly to the CVGHM response team. This information allowed CVGHM to assess the magnitude of the eruption and areas affected, thereby informing their decisions regarding the extent of evacuations needed. In addition, the on-site VDAP crisis-response team provided technical assistance and monitoring equipment to help CVGHM replace systems destroyed in the early phase of the eruption and to expand their monitoring program. Although ~350 fatalities were recorded, it is estimated that CVGHM decisions regarding the extent of evacuations required and prompt actions by the Government of Indonesia saved tens of thousands of lives.