ANALISIS SINYAL SEISMIK DAN SELF POTENTIAL (SP) DARI FENOMENA SEISMOELEKTRIK DI GUNUNG LUMPUR BLEDUG KUWU JAWA TENGAH; ANALYSIS OF THE SEISMIC AND SELF POTENTIAL (SP) SIGNAL FROM SEISMOELECTRIC PHENOMENON IN CENTRAL JAVA BLEDUG KUWU MUD VOLCANO
LAODE IHKSAN JUARZAN, Wahyudi
2015 | Disertasi | FMIPABledug Kuwu is one of the mud volcano (gunung lumpur) in Java. Bledug Kuwu eruption periodically occured with a frequency of more than five times in one minute, pointed by the release of gas bubbles and mud. This study aims to observe the signals of the seismic and self potential (SP) from seismoelectric phenomenon generated by Bledug Kuwu eruption. Measurements were performed by placed seismic sensor around the main crater point of Bledug Kuwu mud volcano, while the SP sensor placed in the vertical, the radial and tangential direction from the point of the main crater of a Bledug Kuwu mud volcano. The analysis was performed by determining the seismic and SP signals dominant frequency, calculating the arrival time different between seismic signal and the SP signal, determining the amplitude value of the seismic and SP event, finding the relationship between amplitude of the seismic and SP events. The result of analysis shows that the dominant frequency of seismic events is 0,2 Hz, while dominant frequency of SP signals is 48,0 Hz. The arrival time difference between seismic and SP signals predominantly in the range of time (0,0 to 1,5 second) which indicates that the appears of the seismic signal causes the appearance of the signal SP as a result of the transfer fluid as described in the seismoelectric phenomenon.The average value of the amplitude of seismic events for Z, NS and EW component is 0,6694, 0,4848 and 0,5158 Count/Volt. The average value of the amplitude of SP events for Z, NS and EW component is 1,338, 1,249 and 0,909 mVolt. SP events will appear if amplitude of seismic events more than 0,2 Count value. Amplitude of sesmic events proportional to the amplitude of the SP event with value of the correlation coefficient between the both is more than 80.0%, the seismic events caused the material in its path have excessive pressure that pore fluid in the material move and cause the separation of charge is the source of the appear of SP signal, the greater the amplitude of the seismic event the pressure exerted on the material so that the larger the amplitude of the SP events formed also getting bigger, this is in accordance with the theory of the seismoelectric phenomenon by electrokinetic effect mechanism .
Kata Kunci : Bledug Kuwu, Self Potential (SP), seismic, dominant frequency, different arrival time, amplitude and seismoelectric effect.
