Japan Geoscience Union Meeting 2022

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[E] Oral

S (Solid Earth Sciences ) » S-SS Seismology

[S-SS04] Seismic Spectra for Source, Subsurface Structure, and Strong-motion Studies

Mon. May 23, 2022 10:45 AM - 12:15 PM 103 (International Conference Hall, Makuhari Messe)

convener:Takahiko Uchide(Research Institute of Earthquake and Volcano Geology, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST)), convener:Rachel E Abercrombie(Boston University), Kuo-Fong Ma(Institute of Geophysics, National Central University, Taiwan, ROC), convener:Kazuhiro Somei(Geo-Research Institute), Chairperson:Takahiko Uchide(Research Institute of Earthquake and Volcano Geology, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST)), Rachel E Abercrombie(Boston University), Kuo-Fong Ma(Institute of Geophysics, National Central University, Taiwan, ROC), Kazuhiro Somei(Geo-Research Institute)


11:45 AM - 12:00 PM

[SSS04-11] Spectral analysis for precise estimation of seismic attenuation

*Junichi Nakajima1 (1.Department of Earth and Planetary Sciences, Tokyo Institute of Technology)

Spectral analyses of seismic waveforms have been used to estimate source parameters of earthquakes (corner frequency and stress drop) and medium heterogeneity (direct and coda attenuation). However, we often have a strong tradeoff, for example, between corner frequency and attenuation because both parameters control the high-frequency fall-off of each spectrum. We developed a new method to avoid the trade-off using two-step approaches and was able to estimate seismic attenuation with high resolution in space and time (Nakajima et al., JGR, 2013; Nakajima and Uchida, Nature Geoscience, 2018). In this talk, we will present two spectral analysis methods and show that they were able to reveal high-resolution 3D seismic attenuation model and temporal variation in attenuation. The former method will improve our understanding sub-surface attenuation structures associated with magmatism and fault heterogeneity, while the latter one will highlight the migration of fluids along the megathrust boundary and immediately below active volcanoes.