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Tectonics or magma intrusion?-- new results from multi-parameter studyat Gede Volcano, West Java, IndonesiaD Hidayat1, H Gunawan2, M Hendrasto2, A Basuki2, F Schwandner1, S Marcial1, SKunrat21 Earth Observatory of Singapore, Nanyang Technological University2 Center for Volcanology and Geological Hazard Mitigation, Indonesia
Flank CO2 flux measurement campaignsHighlight: 2011 NE sector: higher CO2 activity 2011-2012 flank CO2 flux : •Campaigns: • May, Sept 2011 (n 134) • March 2012 (n 40) •Method: • high resolution CO2 accumulation chamber (LICOR Li8100A) • ~10 points/day, >3/site •Results [CO2 g/m2/d]: • 019.8 mean (2011) 112.5 max (2011) • 011.7 mean (2012) 043.4 max (2012) Compare flanks Gede -Merapi mean ~40, max ~120 g/m2/day (9/2002 at Woro) Toutain et al. 2002, Figs.1,8
Possible source causing the earthquakes:-tectonic related earthquakes (faulting)-DVT (distal VT)
Concluding Remarks-Prior to the swarm in Feb-Mar 2012 and Aug 2012, sequences ofsmall earthquakes occurred along NE-SW across Gede andPangrango.-A short VT swarms occurred 27 Feb-8 Mar 2012. We postulatesthat there may be a magma intrusion under Gede volcano but donot lead to any eruption. Similar swarms occurred in 1997 werelocated under Gede Volcano.-Tilt data suggest deformation is controlled by local tectonic untilearly Nov 2011. Then tilt vector change suggests inflation due to(possibly) magma intrusion, followed by swarm of earthquakes at theend of Feb 2012. Several months later tilt data is back to NEdirection. While CO2 flux measurements around Gede suggest somehigh flux around NE from the volcano.-Gede & Salak activity need to be continously monitored with multi-parameter stations as any larger swarm, deformation, or gas fluxchanges may lead to surface activity (eruption) which will affectpeople living around the volcano.