PEMBUATAN MODEL FISIS LETUSAN GUNUNG LUMPUR BLEDUG KUWU DAN PEMODELAN NUMERIK UNTUK MENGETAHUI KECEPATAN PERAMBATAN GELOMBANG SEISMIKNYA; PHYSICAL AND NUMERICAL MODELING OF BLEDUG KUWU MUD VOLCANO ERUPTION TO DETERMINE THE VELOCITY OF SEISMIC WAVE PROPAGATION

AHMAD FAUZI POHAN, Wiwit Suryanto

2015 | Disertasi | FMIPA

Bledug Kuwu mud volcano activity in Central Java is an interesting phenomenon to be studied using both physical and numerical modeling. The objective of this study was to determine the physical parameters of the medium and to help the interpretation of the subsurface structure of Bledug Kuwu. The Physical model was an aquarium with a dimension of 59 × 59 × 37.3 cm filled with Bledug Kuwu?s mud. The eruption source is generated by a compressor pressure that can be controled both the depth and the angel of the source. The resulting seismic signals were recorded by using 3 vertical component geophones for 10 and 5 seconds durations at a frequency of 2 and 4 kHz respectively. Numerical modeling was done by using a finite-difference method with a convolutional perfectly matched layer (CPML) to fit the results from the physical modeling. The source and geophone configuration was also made with the same configuration as the physical modeling. The physical modeling shows that the P-wave velocity of the Bledug Kuwu?s medium is 48.7 m/s with a dominant frequency of 20 to 25 Hz. The comparison of seismogram from physical and numerical model gives S-wave velocity 28.1 m/s, mud density 1200 Kg/m3. It also shows the conduit of the Bledug Kuwu mud volcano system 30° dipping. The correlation of the physical and numerical model is 0.9.

Kata Kunci : N