During the last century, Merapi eruptions characterized by effusive dome growth and collapsed producing “Merapi Type” pyroclastic flows. The eruption of Mt. Merapi in November 2010 was more explosive, a VEI 4 eruption, involving large size dome and fountain collapse pyroclastic flows as well as ash falls. To obtain the deformation precursor to the eruption, we applied a Differential Interferometric Synthetic Aperture Radar (D-InSAR) with short-continuous baseline method using ALOS PALSAR data. We collected 38 scenes single and dual polarization modes in total. Among them, there are only 25 scenes plausible for D-InSAR analysis due to low coherency and data quality. To reduce the atmospheric disturbance in the interferograms, we combined the Pair-wise Logic (PWL) with Referenced Linear Correlation (RLC) method. The Electronic Distance Measurement (EDM) and Seismicity statistics prior to the eruption were used to know the correction performance. This proposed method was proved effective to reduce the atmospheric phase twice from deformation phase.

Fig.1. Original interferogram containing deformation, atmospheric delay, and noise.

Fig.2. Interferogram after atmospheric phase delay removal.

Source:

Saepuloh A., Urai M., Evaluating the Deformation and Atmospheric Signals in the InSAR of ALOS PALSAR data at Mt. Merapi, Abstract of Workshop on Renovation of Observation of Natural Disaster 2012, DPRI-Kyoto University, Japan, pp. 3-7, September 2012.