4:15 PM - 4:30 PM
[HTT19-16] Two-dimensional microtremor survey by chain array
Keywords:microtremor survey method, chain array, near surface
In this study, we show three cases. The first case is a near surface exploration of the crack zone in the Aso caldera caused by the 2016 Kumamoto earthquake. Detailed phase velocity distribution up to 30 m near surface was obtained with a line arrangement orthogonal to the cracks. We created a detailed 3D terrain model using UAV and captured the exploration cross section and visualized it. As a result, we obtained a low velocity distribution (Fig. 1a) that almost coincided with the cracks and graben.
Next are two cases, aiming at the visualization of the buried valley structure. An embankment road in Hashima, the buried valley was confirmed on the western end of the survey line (Fig. 1b) and in the Ikeda pond was almost in the center (Fig. 1c). In any of the chain array exploration, we obtained two - dimensional phase velocity distribution was effective as information of near surface.