Feasibility Study of AMT Application to Sedimentary Structure of Tidal Flat

We have applied the audio-frequency magnetotelluric (AMT) method to the intertidal deposits of Gunhung Bay, west coast of Korea, and analyzed the field data both qualitatively and quantitatively to investigate the morphology and sedimentary stratigraphy of the tidal flat. In order to test the sensitivity of AMT responses, the AMT inversion results were compared with the seismic section. The AMT survey and seismic survey both show the three-layered structure comprising unconsolidated deposits, semi-consolidated sedimentary rocks, and metasedimentary basement. The inversion of AMT data well reveals the upper sedimentary layer of Holocene intertidal sediments. However, it is thought that the AMT inversion tends to overestimate the depth of basement when compared with the seismic section. Since MT responses are not significantly sensitive to the resistivity of middle layer or the depth of basement, the AMT inversion result for the basement may have to be adjusted using other geophysical information like a seismic section or logging data if possible.