A study on tsunami inversion analysis was conducted using Lasso regression, which is a typical approach to sparse modeling. Characteristics of spatiotemporal distribution of the fault slips were then analyzed. Sparse modeling is characterized by yielding obtained solutions that contribute significantly to the output of the model. This feature is useful for investigating the development of prediction models. This paper applies a tsunami inversion analysis based on sparse modeling to the 2011 Tohoku Earthquake Tsunami and analyzes the characteristics of the fault slips.
On April 25, 2015, Gorkha earthquake occurred about 80 km northwest of Kathmandu. In Patan, masonry structures collapsed in Durbar Square. The two-story masonry building that is the subject of this study, is about a 5-minute walk from Durbar Square. Although the building did not collapse, cracks were confirmed in several places. Microtremor measurements performed before and after the earthquake revealed that the natural frequencies of the building decreased. This study examined the factors that decrease the natural frequencies of buildings by seismic response analysis using ground motion estimated by the H/V spectrum ratio as input.
The effects of partial fairings and open grating slabs on reducing tsunami-induced forces on bridges were studied. Fairings are an effective measure to reduce drag,but have limited effect on reducing lift. Therefore, this study conducted numerical simulations with the objective of identifying an effective combination consisting of a partial fairing and an open grating floor slab. The results showed that a fairing that covers more than 75% of the length with an open grating slab could reduce drag by more than 20% and the lift by more than 30% compared to the original bridge model.