5:15 PM - 7:15 PM
[SCG55-P26] Seasonal change of distribution of fin whale signals along the Japan trench deduced from continuous seafloor seismic observation
Keywords:S-net, fin whale call, seasonal migration
NIED ( National Research Institute for Earth Science and Disaster Resilience ) launched the project of construction of S-net, a seafloor observation network for tsunami and earthquake on the seafloor, just after the occurrence of the 2011 Tohoku earthquake. S-net is the online and real-time seafloor observation network of 150 observatories for earthquakes and tsunamis along the Japan Trench. It covers the focal region of the 2011 Tohoku earthquake and its vicinity regions. All the data from 150 seafloor observatories are being transferred to the data center and being automatically processed for monitoring of earthquake activities in these regions.
We have investigated noise sources that contaminated seismic signals recorded by S-net and cause deteriorating of automatic earthquake detection capability. One of such noise sources is fin whale signal ( call ) caught on the seismic velocimeter. Waveforms of fin whale signals have characteristic spectral peaks in narrow frequency bands of 14-25 Hz. They have a short duration of about one second and are repeated at regular intervals of several tens of seconds.
Mochizuki et al. (2021, 2022, 2023, 2024) performed the analysis, based on the method of Nakamura and Iwase (2020), on the S-net seismic observation data for 2020, 2021, 2022 and 2023, respectively. They found similar seasonal distribution pattern of fin whale signals from northeast to southwest direction in all 2020 to 2023, just as Nakamura and Iwase (2020) reported for the S-net data from 2017 to 2019.
Monitoring and counting the fin whale signals within S-net area with the method by Nakamura and Iwase (2020) have continued, in order to understand characteristics of observation environment at each of S-net observatories. We report spatio-temporal distributions of fin whale signals recorded by S-net observatories in the year of 2024 in this presentation.
We have investigated noise sources that contaminated seismic signals recorded by S-net and cause deteriorating of automatic earthquake detection capability. One of such noise sources is fin whale signal ( call ) caught on the seismic velocimeter. Waveforms of fin whale signals have characteristic spectral peaks in narrow frequency bands of 14-25 Hz. They have a short duration of about one second and are repeated at regular intervals of several tens of seconds.
Mochizuki et al. (2021, 2022, 2023, 2024) performed the analysis, based on the method of Nakamura and Iwase (2020), on the S-net seismic observation data for 2020, 2021, 2022 and 2023, respectively. They found similar seasonal distribution pattern of fin whale signals from northeast to southwest direction in all 2020 to 2023, just as Nakamura and Iwase (2020) reported for the S-net data from 2017 to 2019.
Monitoring and counting the fin whale signals within S-net area with the method by Nakamura and Iwase (2020) have continued, in order to understand characteristics of observation environment at each of S-net observatories. We report spatio-temporal distributions of fin whale signals recorded by S-net observatories in the year of 2024 in this presentation.