Seismic microtremor experiment to determine seismic vulnerability of North Aceh

Abstract North Aceh is an area in Aceh, Indonesia, which is crossed by the active Lhokseumawe Fault. The existence of Lhokseumawe fault makes North Aceh relatively vulnerable to seismic hazard. The seismic vulnerability consists of two main components, natural frequency and amplification factor. Microtremor measurement is necessary in order to obtain natural frequency and amplification factor of certain area. A microtremor experiment has been conducted to understand the seismic vulnerability in north Aceh. The seismic microtremor has been measured at 30 sites which are located relatively evenly in the Lhokseumawe City. The measurement result is processed using Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the main components of seismic vulnerability. The natural frequency and amplification factor are able to be calculated. The seismic vulnerability index calculated form natural frequency and amplification factor is also successfully calculated. The area located in the south of the Lhokseumawe Fault is seismically more vulnerable which is also correlated with the rock’s formation of the area. The results are still preliminary that needs more information from the seismic wave velocity representing the characteristics of rocks or soils.