Estimation Site Effect From The Seismogram

A seismogram is a combination of several important information, namely source effects, path effects, and site effects. The location effect provides initial information about the amplification of the receiving station's soil layer response in the event of an earthquake. This study aims to obtain site effect information by analyzing spectrum seismograms. The seismogram data used are seismograms at Wanagama Yogyakarta (UGM), Jajag Banyuwangi (JAGI), and Cisompet Garut (CISI) stations for earthquake events in the Intraplate and subduction areas. To determine the source effects, path effects, and site effects by analyzing the displacement spectrum using Simple Nelder's nonlinear inversion method. The results of spectrum analysis and inversion processes are site effects spectrum curves. The results of spectrum analysis and inversion process are location effect spectrum curves. From the site effect, the spectrum curve shows that JAGI and CISI stations cannot be used as reference stations because they still have site effects in decreasing amplitude in the frequency range of 0.1 - 1 Hz. The magnitude of CISI station amplification ten times from the JAGI station that occurs in the 5-10 Hz frequency range by pointing to the UGM station as a reference station.