S-wave velocity of soil layers is needed to calculate earthquake ground responses, but the cost of observing S-wave velocity is high. Therefore, it is often estimated from various soil data such as N-value. However, the variation in the S-wave velocity measured from N-value is very large. The purpose of this study is to examine the effects of this variation on the earthquake response of base isolated houses using a stochastic method. Results show that a soft ground surface leads to a larger the variation of the displacement response.
