- Copyright © 1992, by the Seismological Society of America
To interpret observations of the upthrow of boulders followed by their remarkable displacement during the 1984 Western Nagano Prefecture, Japan, earthquake, shaking-table experiments, field measurements, and numerical simulations on the upthrow were conducted. First, upthrow of objects was produced during a shaking-table vibration experiment in which table motion was in the horizontal direction only. Next, after field measurements on the ground and boulders were carried out to determine the parameters in the numerical simulations, a series of numerical simulations was conducted using the distinct element method. Both the experimental and numerical approaches not only resulted in reinforcement of Newmark's argument (1973) that the upthrow does not necessarily indicate vertical ground acceleration greater than that of gravity, but further extended it to quantitative assessment of ground-motion intensity.