CAP ROCK ZONE INTERPRETATION BASED ON 2D MODEL OF MAGNETOTELLURIC DATA IN AKESAHU, TIDORE, NORTH MALUKU, INDONESIA

Abstract:

There have been conducted magnetotelluric survey in Akesahu and surrounding area to obtain time series data in several electromagnetics component (Ex, Ey, Hx, Hy, and Hz) with the target of cap rock zone in local geothermal system. The survey was completed with 10 sounding points which are divided into two lines. The data was being processed in several step, they were Fourier transform, Robust Processing, Smoothing, and 1D/2D Modelling using SSMT, MTEditor, and WingLink. The final objective of the processing is to obtain 1D and 2D resistivity model in Akesahu. The interpretation scope of cap rock zone includes resistivity range value and the depth of the cap rock. Interpretation of 1D and 2D resistivity model shows high – low – high resistivity ranges value from the surface to the maximum depth at 10.000 meters based on regional stratigraphy correlated with resistivity table from various source. In Line 01, cap rock zone defined in low resistivity range 1 – 8 Ωm at the depth of 970 – 2100 m, while in Line 02 the cap rock zone defined in resistivity range of 0,78 – 8 Ωm at the depth of 500 – 2000 m. Based on Akesahu stratigraphy, the cap rock interpreted as Kayasa Formation (Pleistocene) that consist of basaltic and andesitic tuff.