Scattering and intrinsic absorption parameters of Rayleigh waves at 18 active volcanoes in Japan inferred using seismic interferometry

Assessing the relative seismic properties of volcanoes is essential because it improves our understanding of the similarity and diversity of processes occurring in magmatic and hydrothermal systems, thereby contributing to a comprehensive understanding of these systems. Scattering and absorption are among the most challenging but useful parameters to obtain to discriminate volcanic structures. However, the separation of scattering from absorption generally relies on active seismic data or earthquake activity. We estimated seismic scattering and intrinsic absorption parameters of Rayleigh waves at 18 active volcanoes in Japan using seismic ambient noise. The use of cross-correlation functions enables the estimation of these parameters in volcanoes where there are no active seismic data available and with insufficient earthquake activity. The scattering and intrinsic absorption parameters from the 18 volcanoes are about two orders of magnitude larger than those in non-volcanic regions, indicating strong medium heterogeneity in the shallow regions of those volcanoes, as the Rayleigh waves in our target frequency are mainly sensitive to subsurface structures shallower than 1 km in depth. Volcanic islands and volcanoes near the coastline or lakes show the highest intrinsic attenuation and frequency dependence, likely caused by widespread water-saturated regions beneath the volcanoes. Our study highlights both similarities and differences in scattering and absorption properties across the 18 volcanoes. Further developing passive estimation capabilities to better constrain scattering and absorption parameters will allow us to distinguish differences in fracturing and pore space properties of the subsurface medium and will contribute to detailed studies of complex subsurface structures at active volcanic systems.

Automated summary

Assessing the seismic properties of volcanoes through ambient noise can provide valuable insights into the heterogeneity of subsurface structures, with volcanic islands and coastlines showing higher intrinsic attenuation due to water-saturated regions. The study highlights the importance of passive estimation techniques in understanding volcanic systems and the need for further research to differentiate fracturing and pore space properties in subsurface mediums.