When the safety of railway facilities and running vehicles are threatened by large shakings of ground motions during earthquakes, railway operators stop trains as soon as possible. After the safety of train operation are ensured by a cautious inspection patrol along the railway section following the rule decided in advance, the train operation is resumed. To confirm visually the damage of railway facilities and deformation of railway tracks in the inspection, it may take a lot of time. It is necessary to carry out the safety inspection more precisely and effectively, for shortening downtime of regular train operation. Therefore to comprehend exactly the characteristics of earthquake ground motions along the target railway, the rapid evaluation of the earthquake ground motions, not only at the points where the seismographs are installed at equal intervals but also at the other points on the railway, are strongly required.
In this study, we adopted Miyazaki maglev test line, which has a total length of 7 km, located in the middle coast of Miyazaki prefecture, as a model railway. We tried to estimate the continuous linear S-wave velocity structures and earthquake ground motions along Miyazaki maglev test line. At first, we tried to estimate S-wave velocity structures at two sites where seismographs are installed, using the geophysical exploration such as surface wave exploration and array microtremor survey. Secondly, we estimated the continuous linear S-wave velocity structures on the model railway, based on the S-wave velocity structures estimated by the geophysical exploration method, using the H/V spectral ratios obtained by the high-dense microtremor measurement. Finally, we estimated the high-dense earthquake ground motions along Miyazaki maglev test line by the one-dimensional multiple reflection theory. We confirmed the validity of the continuous linear S-wave velocity structures and the estimated earthquake ground motions along Miyazaki maglev test line, through the comparison with the observed earthquake ground motions.
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