11:00 〜 11:15
[SVC28-02] 干渉SAR時系列解析による火山活動モニタリング
キーワード：火山活動、干渉SAR、地盤変動
The Centre for the Observation and Modelling of Earthquakes Volcanoes and Tectonics (COMET), in the UK conducts the Looking Inside the Continents from Space (LiCS) project, which primarily aims at understanding how the continents deform at all spatial and temporal scales, with a focus on using observations of the earthquake deformation cycle to understand how seismic hazard is distributed in space and time. And the project develops an automated InSAR processing system, LiCSAR (Lazeckýet al., [1]) using the earth observing satellite Sentinel-1 by European Union (EU) and the European Space Agency (ESA). Morishita et al. [2] releases LiCSBAS, an open-source SAR interferometry (InSAR) time series analysis package that integrates with LiCSAR.
All programs of LiCSBAS are written in Python3 and a bash script controls the sequence of the steps such as downloading LiCSAR products, data conversion, down-sampling, propagation delay correction, masking and clipping, quality checking (QC), small-baseline inversion, error estimation, time-series masking, and filtering. It also includes plentiful tools to convert formats among float, GeoTIFF, KMZ, and text, to draw LOS displacement maps and time-series, to calculate 2.5-dimensional displacements (Fujiwara et al., [3]), and so on.
Applying LiCSBAS to Sakurajima volcano for the period from Aug., 2015 to Aug., 2020, the InSAR time-series analyses revealed the uplifting in the area along the NE coast of the island with the maximum rate of about 10 mm/year. Yamamoto et al. [4] derived the similar result using repeated precise leveling for the period from 1996 to 2010 and suggested a model of the pressurized magma reservoir beneath Aira caldera. The other characteristic obtained by the InSAR time-series analyses is the subsidence around the SE frank of the summit, where Morishita et al. [6] retrieved uplifting and eastward displacements due to the magma intrusion event in 2015 based on InSAR analysis and proposed a dike model beneath the Showa crater at a depth of 0.4–1.2 km.
Applying LiCSBAS to Kuchierabujima volcano for the period from 2015 to 2020, extensional LOS displacements are noticeable around the summit area both for ascending and descending tracks and suggesting the subsidence in the area. There have been three major eruptions in the last decade; Aug. 2014 (VEI1), May – Jun., 2015 (VEI3), and Oct. 2018 – Feb. 2019 (VEI3), when the overall eruptive activity resulted in the contractive deformation as mentioned above. The Japan Meteorological Agency reported that the extensional baseline length change started around Oct. 2019 suggesting a deeper pressure source. The InSAR results shows that the subsidence rate around the summit area slows down almost in the same period.
These two application examples suggest that the InSAR time series analysis is useful and effective in volcano monitoring.
References:
[1] Remote Sens. 2020, 12, 2430; doi:10.3390/rs12152430. [2] Remote Sens. 2020, 12, 424; doi:10.3390/rs12030424. [3] GRL, 2000, 27, 2049–2052. [4] BVSJ, 2013, 58, 137-151. [5] GRL, 2016, 43, 4197-4204.
All programs of LiCSBAS are written in Python3 and a bash script controls the sequence of the steps such as downloading LiCSAR products, data conversion, down-sampling, propagation delay correction, masking and clipping, quality checking (QC), small-baseline inversion, error estimation, time-series masking, and filtering. It also includes plentiful tools to convert formats among float, GeoTIFF, KMZ, and text, to draw LOS displacement maps and time-series, to calculate 2.5-dimensional displacements (Fujiwara et al., [3]), and so on.
Applying LiCSBAS to Sakurajima volcano for the period from Aug., 2015 to Aug., 2020, the InSAR time-series analyses revealed the uplifting in the area along the NE coast of the island with the maximum rate of about 10 mm/year. Yamamoto et al. [4] derived the similar result using repeated precise leveling for the period from 1996 to 2010 and suggested a model of the pressurized magma reservoir beneath Aira caldera. The other characteristic obtained by the InSAR time-series analyses is the subsidence around the SE frank of the summit, where Morishita et al. [6] retrieved uplifting and eastward displacements due to the magma intrusion event in 2015 based on InSAR analysis and proposed a dike model beneath the Showa crater at a depth of 0.4–1.2 km.
Applying LiCSBAS to Kuchierabujima volcano for the period from 2015 to 2020, extensional LOS displacements are noticeable around the summit area both for ascending and descending tracks and suggesting the subsidence in the area. There have been three major eruptions in the last decade; Aug. 2014 (VEI1), May – Jun., 2015 (VEI3), and Oct. 2018 – Feb. 2019 (VEI3), when the overall eruptive activity resulted in the contractive deformation as mentioned above. The Japan Meteorological Agency reported that the extensional baseline length change started around Oct. 2019 suggesting a deeper pressure source. The InSAR results shows that the subsidence rate around the summit area slows down almost in the same period.
These two application examples suggest that the InSAR time series analysis is useful and effective in volcano monitoring.
References:
[1] Remote Sens. 2020, 12, 2430; doi:10.3390/rs12152430. [2] Remote Sens. 2020, 12, 424; doi:10.3390/rs12030424. [3] GRL, 2000, 27, 2049–2052. [4] BVSJ, 2013, 58, 137-151. [5] GRL, 2016, 43, 4197-4204.