Comparison of High-resolution P- and SH-wave Reflection Seismic Data in Alluvial and Pyroclastic Deposits in Indonesia

High-resolution, P- and SH-wave seismic reflection profiles were acquired at two different locations in Indonesia to test the capability of imaging in pyroclastic sediments. The seismic measurements for both locations were carried out using a 48-channel recording system, and sledge hammer and micro-vibrator ELVIS as sources. The results of seismic data in Semarang show fair to good seismic records for both P- and SH-waves. The raw data contain a high signal-to-noise ratio. Many clear reflectors can be detected. The P-wave data show reflectors down to 250 ms two-way time while the SH-wave records show seismic events up to 600 ms two-way time. This result is in strong contrast to the observations in the Tiris region. Here, the P-wave data show a very low signal-to-noise ratio, and there is no reflection signal visible, only the surface waves and the ambient noise from the surrounding area are visible. The SH-waves give a fair to good result which enables reflector detection down to 300 ms two-way time. Thus, the SH-wave reflection seismic seems to be the suitable method, which could be applied in Indonesia in both alluvial and pyroclastic regions.