Detecting Surface Structures after Large Eruption of Mt. Merapi in 2010 Using ALOS/PALSAR Data

Abstract Mt. Merapi located in central Java is one of the most active volcanoes in Indonesia. Its activity is characterized by small eruptions with periodicities ranging from one to five years. Eruptions of the last century were characterized by effusive lava dome growth and collapse to produce “Merapi type” pyroclastic flows. However, the characteristics of Merapi eruptions have changed in November 2010. The eruptions are more explosive (VEI 4), involving exceptionally rapid dome growth and collapse that produced extensive pyroclastic flows and heavy ash fall. Following the extra-ordinary eruption, we evaluated the changes of surface structures by quantifying the Linear Features Density (LFD) related to the geological structures before and after eruption using dual observation of ALOS/PALSAR data. An automatic extraction of linear feature density from Synthetic Aperture Radar (lifedSAR) was applied to quantify the LFD. Statistically, the LFD increased to about 85% after the eruption with the location of maximum density at Southern flank. The high fractured zones were located at NW and NE from the summit. The zones could be served as fluid path of meteoric water infiltration to the subsurface. Therefore, the path may connect the water to the hot materials beneath the surface.