2:00 PM - 2:15 PM
[STT57-08] Crustal deformation and crater depth change before and after the 2015 dyke intrusion event of Sakurajima volcano investigated by SAR analysis
Keywords:SAR, Crustal deformation, Sakurajima
We investigated crustal deformation and depth change of Syowa crater before and after the dyke intrusion event by SAR analysis. In crustal deformation detection by InSAR analysis, we used the atmospheric delay noise reduction method using numerical weather model (e.g., Ozawa and Shimizu, 2010) and the ionospheric delay noise reduction method by the split-spectrum method (e.g., Gomba et al., 2015). Crustal deformations obtained from descending right-looking PALSAR-2 data indicate slant-range contraction exceeding 5cm in the west area of Sakurajima just before the dyke intrusion event. Although this might have been precursor of the dyke intrusion event, more investigation about significance of this signal is necessary. On the other hand, slant-range extension was obtained in east of Syowa crater after the dyke intrusion event. This crustal deformation started just after the dyke intrusion event and decayed over time. Then it must have related to the dyke intrusion event. However its spatial pattern is obviously different to that for the dyke intrusion. Then it is necessary to consider a mechanism different from the tensile fault for dyke intrusion. Additionally, slant-range contraction was obtained in northwest of the Kita-dake. It seems that this deformation has started from the 2016 summer.
We estimated depth change of the Syowa crater from feature of SAR Layover. Although slight depth changes were estimated in periods that explosions had occurred actively, it did not exceed several tens of meters. It suggests that pressure condition under the Syowa crater has not changed significantly.