Installation Method of the Caisson in the Seafloor for High-Quality Seismic Observation

In seafloor seismic observation, the seismometer is usually installed on the seafloor. The data obtained from the seismometer installed on the seafloor is influenced by background noise. Therefore, in seafloor observation, it is necessary to install seismometer with consideration of influence depending on installation environment for observation with high accuracy. We investigated that whether the observation site is suitable to penetrate the caisson. If the tentative site is determined to be unsuitable for installation of the casing, an alternative site is selected near the tentative site. After that, a sediment sampling is carried out and the evaluation of soil mechanics of sediment. In the construction of DONET2, we have investigated more than thirty core samples of the observatories. In this paper, we introduce the evaluation results about our location selection based on the sediment sampling and the state-of-the-art installation method of the caissons of DONET2.