Assessing the Subsurface Characteristics Using Electrical Resistivity Tomography in Penang

A 2D electrical resistivity tomography study was conducted in Jelutong, Penang, to characterise the subsurface condition using the electrical resistivity tomography method. This was also done to evaluate physical subsurface parameters, and the available borehole log data correlated well with the obtained results. On the basis of the data interpretation, a number of zones with relatively equal resistivity values were mapped and identified at three different lines. Line 1's inverse resistivity model revealed a high resistivity zone range from (1300-1800 ohm-m) on the right side of the survey line and a low resistivity zone ranges from (10-390 ohm-m) in the middle. The high resistivity zone defines the basement rocks as well as the concrete basketball court, whereas the low resistivity zone corresponds to the shallow groundwater level. According to the borehole log, the inverse resistivity model for Line 2 indicated a low resistivity zone ranges from (10-390 ohm-m) less than 4 m depth and a high resistivity zone range from (1300-1800 ohm-m)  greater than 5 m depth. The high resistivity body displayed in the saturated zone is interpreted as a boulder, whereas the scale shows variations of low resistivity values due to the high saturation of the subsurface. In addition, The Line 3 inversion model indicates the resistivity values are between the range of 10–1800 ohm.m. The inversion model shows a saturated zone on top, which is interpreted as very stiff silty sand. Sand's capacity to hold water resulted in a low resistivity value.