Joint Inversion of RMT and TEM Data for Mapping Active Faults in Northern Greece

Abstract

Northern Greece is an area with one of the most seismically active region in Europe. Several earthquakes occurred during 20th century. The largest earthquake in recent time with magnitude of 6.5 happened in June 1978. The objective of the presented study is to investigate local geological structure and the top of the basement of the Volvi Basin, Northern Greece. The geophysical surveys are carried out using electromagnetic methods, Radiomagnetotelluric (RMT) and Transient electromagnetic (TEM). The investigations are limited to near surface studies with shallow depth (< 200 m). It is expected that the complex geological structure and the vertical distribution of resistivity layers can be defined by RMT and TEM methods. Joint inversion can increase the number of important model parameters and it can also decrease the ambiguity of the model. The result of joint inversion was in agreement with assumption as the RMT data are resolved the surface layer at depth down to 40 m, and TEM data is small enough to resolve the surface structure (z < 10 m), however it can resolve the deeper structure down to 200 m of depth, depending on the resistivity structure. The joint and sequential models can both represent 1-D single inversion of RMT and TEM data. The model parameters are well resolved in joint inversion in comparison with the single RMT and TEM inversions. Hence, the joint inversion of RMT and TEM data will produce good resolution of model parameters in shallow and deeper parts of fault structure.