日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 S (固体地球科学) » S-TT 計測技術・研究手法

[S-TT45] 合成開口レーダー

2019年5月27日(月) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:木下 陽平(筑波大学)、森下 遊(国土地理院)、小林 祥子(玉川大学)、阿部 隆博(国立研究開発法人宇宙航空研究開発機構 地球観測研究センター)

[STT45-P02] Mitigation of atmospheric delay in InSAR for fair estimate of crustal deformation at Azumayama volcano

*阿部 華菜1小川 佳子1久田 泰広1出村 裕英1小澤 拓2三浦 哲3日下部 玲1荒井 雄大1 (1.公立大学法人会津大学、2.防災科学技術研究所、3.東北大学大学院理学研究科)

キーワード:吾妻山、地殻変動、火山、合成開口レーダー、数値気象モデル

Azumayama volcano is one of the five active volcanoes in Fukushima prefecture which is now issued volcanic alert level 2. Since 2014 winter, the volcano had/has been issued the level 1 and 2 repeatedly according to the situation. It is the most active volcano in the Fukushima pref. We have been working to clarify time-series of crustal deformation at Azumayama volcano.

Abe et al. [2017, JpGU] conducted InSAR (Interferometric Synthetic Aperture Radar) analysis using ALOS2 (Advanced Land Observing Satellite 2)/PALSAR2 (Phased Array L-band Synthetic Aperture Radar-2) data and estimated crustal deformation around Azumayama volcano . However, some of the results showed subsidence at the west of Azumayama which would be due to atmospheric delay and ionospheric delay.

In this study, we attempted to correct atmospheric delay and ionospheric delay in InSAR analysis using three numerical weather models: MSM (MesoScale Model), LFM (Local Forecast model) and WRF (Weather Research and Forecasting). WRF is created by using MSM data to improve resolution of time. Then we tried to estimate the amount of crustal deformation more precisely from 2014 fall to 2017 fall after applying atmospheric correction. Eight of the ALOS2/PALSAR2 data were used for the InSAR analysis. We evaluated the InSAR results after performing each atmospheric correction based on each numerical model and compare them quantitatively and select suitable weather model among the three.

Artifacts and false fringe in InSAR results seem to be reduced. Comparing InSAR analysis results with the value of GNSS (Global Navigation Satellite System) analysis at ground stations, correction by LFM and WRF showed similar trend better than that by MSM. Numerical weather models with higher resolutions seem effective in correcting atmospheric delay in InSAR. Uplift and subsidence at the Oana crater and subsidence in the western part of Azumayama were detected during 2014 fall - 2015 summer and 2015 summer - 2015 fall, respectively, which reflect actual deformation.