11:30 AM - 11:45 AM
[STT45-04] Surface displacements at the Kumamoto plain using persistent scatterer interferometry and comparison with groundwater levels
Keywords:Surface displacement, the Kumamoto plain, change in groundwater levels
As a result of analysis, we estimated surface displacement with the magnitude of about 2-3 cm along the Futagawa and Hinagu fault systems. We interpreted that the displacements along the fault traces were due to the afterslip. On the other hand, we also found surface displacements apart from the fault traces. For example, surface uplift up to 4 cm/year was observed during about 1 year after the earthquake around the west flank of Aso volcano. The displacement began several months after the earthquake, and generally correlated with the areas of groundwater level increased. Since the displacement pattern was not observed in ALOS/PALSAR results, we speculated that the displacement was induced by the groundwater level changes by the earthquake. In addition, we estimated the skeletal storage coefficients from surface displacements and groundwater levels, and found that the coefficients differed by the earthquake at several locations, indicating the temporal alteration of permeability or compressibility of the aquifer. Our results demonstrate the effectiveness of the surface displacement monitoring combined with groundwater level data at the aquifer system.
Acknowledgements: The ALOS-2/PALSAR-2 level 1.1 data used in this study were provided by the PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land Surface) group in cooperative research with the Earthquake Research Institute, University of Tokyo. The ALOS-2/PALSAR-2 data belongs to the Japan Aerospace Exploration Agency. The groundwater level data used in this study were measured by several public institutes, and the data were corrected by the working group in Japan Association of Groundwater Hydrology.