9:45 AM - 10:00 AM
[SVC29-04] The Sea-Bottom Benchmark system in Aira Caldera and its current performance
Keywords:Ocean-bottom geodetic observations, GNSS, Aira Caldera
The Sea-Bottom Benchmark system (SBB) is introduced and its performance is reported, which was installed in 2.2 kilometers northeast off Sakurajima on March 2023. SBB comprises an anchor of 19 tons weight and a universal coupled buoy of 40 meters length and 21 tons weight. The measureing system comprises four GNSS antennas, two GNSS receivers, a mobile router, and a power supply system. The power supply system includes three iron phosphate lithum-ion batteries, three photo-voltaic cells, and a charge controller. The light beacon is also builted on the buoy top and is turned on after the sunset. Data in the receivers are pulled up once a day through a LTE commercial network, and are processed in the machine in the headquater, SVO, automatically. The position at the top of the anchor is calculated through the attitude correction from GNSS antenna array at the top of the buoy.
The system operation has been running successfully for 320 days after the establishment without any day-long break and stood through strong wind of a typhoon storm. The attitude correction is based on the method on Tsutsui et al. (2022). The location result show a simple normal distribution with the standard deviations of location 0.17 m for lateral components and 0.017 m for the vertical component. The result of the vertical component has been tested with those from the surrounding stations. Although almost flat trend are observed in the surrounding station, the result from SBB shows down slope with increasing time. Difference between these results are around 4 cm and the vertical component shows on-going local subsidence after the installation. The reduction of the local subsidence is necessary to resolve exact ground deformation. The reduction will be perfomed through continueing operation of SBB.
The system operation has been running successfully for 320 days after the establishment without any day-long break and stood through strong wind of a typhoon storm. The attitude correction is based on the method on Tsutsui et al. (2022). The location result show a simple normal distribution with the standard deviations of location 0.17 m for lateral components and 0.017 m for the vertical component. The result of the vertical component has been tested with those from the surrounding stations. Although almost flat trend are observed in the surrounding station, the result from SBB shows down slope with increasing time. Difference between these results are around 4 cm and the vertical component shows on-going local subsidence after the installation. The reduction of the local subsidence is necessary to resolve exact ground deformation. The reduction will be perfomed through continueing operation of SBB.