Distribution of ambient noise at offshore Kii peninsula by using DONET

Studies about ambient noise have been investigated on the North Pacific, the Atlantic oceans and so on. It has been clarified that the increasing ship traffic correlated with an overall increase of the ambient noise level. However, the ambient noise level has not been well measured and analyzed in Japan's coast. Recently, DONET (Dense Oceanfloor Network System for Earthquakes and Tsunamis) was constructed as a submarine cabled real-time seafloor observatory network for earthquake, geodetic and tsunami observation and analysis. This system has 51 observatories, including not only seismic sensors but also hydrophones. These observatories cover about 230 km from east to west and 130 km from north to south. Therefore, it is possible to measure the ambient noise in the large area by using 51 hydrophone's network. It has been clarified that the spatio-temporal distribution of the ambient noise levels, computed from the measured data.