Understanding precursory signal leading to a large and explosive eruption, such as Merapi eruption in 2010, is the key to a successful hazard assessment in the future. Towards resolution of this problem, time series of Differential Interferometric SAR (D-InSAR) of ALOS/PALSAR data together with thermal radiance at summit area were analyzed to characterize magmatic process. The D-InSAR could detect deformation changes in between two eruption episodes of Merapi in 2006 and 2010. The maximum uplifting rate ~0.7 mm/day is observed twice: two years and one month before eruption in October 26, 2011. The first uplift is related to magma ascent and the later is precursory to an imminent eruption. Thermal radiance of ASTER data not only served as indicator on the arrival of fresh magma near the surface, but also to confirm whether or not the deformation signal is related to the imminent eruption.

Fig. 1. Location of Mt. Merapi in Central Java, Indonesia.

Fig. 2. The interferograms of ALOS/PALSAR shows the uplifting and subsidence phenomena prior to the eruption.

Fig. 3. ASTER TIR images of Mt. Merapi from 2006 to 2010. The hot spots indicated the beginning and the ending of one periodical of eruption.

Fig. 4. The estimated-deformation rate at Mt. Merapi.

Source:

Saepuloh A., Urai M., Widiwijayanti C., Aisyah N., Observing 2006-2010 ground deformations of Merapi volcano (Indonesia) using ALOS/PALSAR and ASTER TIR data, Proceeding of the IEEE International Geoscience and Remote Sensing Symposium 2011 (IGARSS-2011), Vancouver, Canada, July 2011.