A simple analysis of MT data in Seulawah volcano by using ModEM webportal

Abstract

Seulawah Agam volcano is one of the locations where manifestations of hot springs are found on the surface, which indicates a geothermal source. ldentifying a geothermal system requires exploration stages from multidisciplinary perspectives such as geology, geophysics, and geochemistry in regions where manifestation was located on the surface. Geophysical exploration using geophysical methods, especially the magnetotelluric (MT) method, has been widely carried out by geoscientists to provide information on subsurface data. The MT method with various frequency ranges of electromagnetic waves allows deeper penetration that can reach depths of up to tens of kilometers. However, this method has various limitations, from acquisition to data processing which requires a lot of effort and budget. One simple thing that can be done to keep up with information related to the geothermal system is by initial analysis of MT data using the ModEM WebPortal. So we get a gradient tipper vector that can help analyze subsurface information related to conductor anomalies that show the physical properties of the geothermal system. The apparent resistivity distribution is also used to support information about the influence of the geothermal system on the existing fault structure. ln general, conductive anomalies are found at different depths of each frequency. However, the center of the anomaly is not consistent at one position at each depth. Change in the center of the anomaly due to the Great Sumatran Fault structure that accommodates hot springs rising to the surface. Manifestations of hot water are found at several points around Mount Seulawah Agam, such as le Sueum, le Busuk, le Jue, Heutz, and Cempaga.