Evaluation of vs,30 estimating models for Indonesia

Series of strong-motion instruments are being installed as part of the seismic hazard reduction program. One of the required information for an instrument station is the geotechnical characteristics, particularly the 30 m deep weighted average of shear wave velocity, V_S,30. The V_S,30 values of 25 strong-motion instrument stations in western part of Java Island and western-southern part of Sumatra Island were used to evaluate the topographical information and the geomorphological information based V_S,30 estimation models. The ratio of the measured V_S,30 to the estimated V_S,30 is evaluated, and the simple statistical parameters could not suggest the better model. No apparent geographical and/or geological factors could be identified as the affecting factor as well. Furthermore, the ratio is found to decrease with increasing the estimated values. Based on these observations, several recommendations are proposed, including to develop a new V_S,30 estimation model, specifically for Indonesia.