金曜日セミナー(1月12日) 中田 令子 氏(海洋研究開発機構)

We estimated spatial distribution of the long-term slow slip events (L-SSEs) beneath the Bungo channel in southwest Japan. The total slip distributions of these L-SSEs estimated by geodetic data have been smoothed to some extent due to prior constraints on inversion analyses.

In this study, by using fused regularization, a type of sparse modelling suitable for detecting discontinuous changes in the model parameters, we found that the largest slip abruptly becomes zero at the down-dip limit of the seismogenic zone, and is immediately reduced to half at the up-dip limit of the deep low-frequency tremors, and becomes zero near its down-dip limit. Such correspondences imply that some thresholds exist in the generation processes for both tremors and SSEs. It suggests that geodetic data inversion with sparse modelling can detect such abrupt changes in the slip distribution.