3:30 PM - 5:00 PM
[SVC35-P01] Sub-theme B-2: Developments of portable radar interferometer and spaceborne SAR interferometry for precise observation of volcano deformation
Keywords:Crustal deformation, SAR, SCOPE
Accurate evaluation of volcanic activity is important in order to predict its transition, and multiple observations are effective for such evaluation. Especially, significant surface phenomena related to volcanic activity often occur around the crater, and we would like to capture such information in detail. However, access to the crater area of an active volcano is hazardous, making observation of the crater area difficult. To solve such problems, the Next Generation Volcano Research Project Sub-theme B-2 is developing remote sensing technology that enables observation of the crater area from remote locations. One of the development items is to create a database of crustal deformation information obtained from synthetic aperture radar (SAR). This will enable anyone to easily access useful crustal deformation information by SAR. In this presentation, we will report on the progress of this development.
In the development related to spaceborne SAR, we will collaborate with the PIXEL, Japanese SAR research community for surface deformation research, and analyze ALOS/PALSAR and ALOS-2/PALSAR-2 data shared among PIXEL. After downloading the data, SAR interferometry and time-series analysis methods are automatically applied, and the resulting crustal deformation information is stored in the Japan Volcanological Data Network (JVDN). The data are stored in the grid data format (NetCDF format) of the generic mapping tools (Wessel and Smith, EOS Trans. AGU, 1998), including slant-range change and line-of-sight vectors. Until now, we have started to release the data for 11 volcanoes (Tokachi-dake, Usu, Zao, Azuma, Kusatsu-Shiranesan, Unzen, Kirishima, Sakurajima, Izu-Oshima, Miyakejima, and Kuchinoerabu-jima). In these volcanoes, surface deformation due to crustal deformation associated with volcanic activity and landslides has been detected. By the end of March 2023, we will release results for additional five volcanoes (Meakan-dake, Iwate-san, Yakedake, Hakone, and Aso).
The temporal resolution of spaceborne SAR is basically limited by the satellite recurrence period, and therefore it is difficult to understand crustal deformation progressing over several days. However, in situations where an eruption is imminent, it is desirable to understand crustal deformation with a higher temporal resolution. In addition, crustal deformation detection using SAR has a disadvantage which is low sensitivity to the north-south component. Furthermore, it is often difficult to accurately measure crustal deformation in steep terrain. To solve these problems, we are developing a portable radar interferometer (sensor name: SCOPE) that can observe crustal deformation by illuminating radar waves from the ground when volcanic activity is observed (Ozawa et al., JDR, 2019; Ozawa et al., JDR, 2022). Unlike conventional ground-based SAR, which is fixed at a certain point, SCOPE observes crustal deformation repeating sensor relocation. To conduct such repeat observation effectively, a radar wave with 1.3 GHz band (L-band), which is less susceptible to scatter change by vegetation, is adopted in this development. In addition, SCOPE has four observation types: GB-SAR, car-borne SAR, cart-borne SAR, and man-borne SAR, which are used to conduct such repeat observations efficiently. Until now, observations using SCOPE were conducted in Kirishima, Asama-yama, Tokachi-dake, Azuma-yama, Kusatsu-Shirane, and Mt. Tsukuba. In particular, observations of Azuma-yama were conducted three times from October 2021 to November 2022, and succeeded in the detection of crustal deformation around the Oana crater related to volcanic activity (Ozawa and Himematsu, JpGU2023). In the future, we will conduct SCOPE observation to investigate crustal deformations of more volcanoes.
In the development related to spaceborne SAR, we will collaborate with the PIXEL, Japanese SAR research community for surface deformation research, and analyze ALOS/PALSAR and ALOS-2/PALSAR-2 data shared among PIXEL. After downloading the data, SAR interferometry and time-series analysis methods are automatically applied, and the resulting crustal deformation information is stored in the Japan Volcanological Data Network (JVDN). The data are stored in the grid data format (NetCDF format) of the generic mapping tools (Wessel and Smith, EOS Trans. AGU, 1998), including slant-range change and line-of-sight vectors. Until now, we have started to release the data for 11 volcanoes (Tokachi-dake, Usu, Zao, Azuma, Kusatsu-Shiranesan, Unzen, Kirishima, Sakurajima, Izu-Oshima, Miyakejima, and Kuchinoerabu-jima). In these volcanoes, surface deformation due to crustal deformation associated with volcanic activity and landslides has been detected. By the end of March 2023, we will release results for additional five volcanoes (Meakan-dake, Iwate-san, Yakedake, Hakone, and Aso).
The temporal resolution of spaceborne SAR is basically limited by the satellite recurrence period, and therefore it is difficult to understand crustal deformation progressing over several days. However, in situations where an eruption is imminent, it is desirable to understand crustal deformation with a higher temporal resolution. In addition, crustal deformation detection using SAR has a disadvantage which is low sensitivity to the north-south component. Furthermore, it is often difficult to accurately measure crustal deformation in steep terrain. To solve these problems, we are developing a portable radar interferometer (sensor name: SCOPE) that can observe crustal deformation by illuminating radar waves from the ground when volcanic activity is observed (Ozawa et al., JDR, 2019; Ozawa et al., JDR, 2022). Unlike conventional ground-based SAR, which is fixed at a certain point, SCOPE observes crustal deformation repeating sensor relocation. To conduct such repeat observation effectively, a radar wave with 1.3 GHz band (L-band), which is less susceptible to scatter change by vegetation, is adopted in this development. In addition, SCOPE has four observation types: GB-SAR, car-borne SAR, cart-borne SAR, and man-borne SAR, which are used to conduct such repeat observations efficiently. Until now, observations using SCOPE were conducted in Kirishima, Asama-yama, Tokachi-dake, Azuma-yama, Kusatsu-Shirane, and Mt. Tsukuba. In particular, observations of Azuma-yama were conducted three times from October 2021 to November 2022, and succeeded in the detection of crustal deformation around the Oana crater related to volcanic activity (Ozawa and Himematsu, JpGU2023). In the future, we will conduct SCOPE observation to investigate crustal deformations of more volcanoes.