Detecting DC Electrical Resistivity Changes in Seismic Active Areas: State-of-the-Art and Future Directions

A critical review of geoelectrical monitoring activities carried out in seismically active areas is presented and discussed. The electrical resistivity of rocks is one of the geophysical parameters of greatest interest in the study of possible seismic precursors, and it is strongly influenced by the presence of highly fractured zones with high permeability and fluid levels. The analysis in this study was based on results obtained over the last 50 years in seismic zones in China, Japan, the USA and Russia. These previous works made it possible to classify the different monitoring strategies, to analyze the theoretical models for interpreting possible correlations between anomalies in resistivity signals and local seismicity, and to identify the main scientific and technological gaps. In addition, much attention is given to some recent work on the study of correlations between focal mechanisms and the shapes of anomalous patterns in resistivity time series, and to the new possibilities offered by the AI-based methods for geophysical data processing. Finally, new strategies and activities for investigating the spatial and temporal dynamics of the electrical resistivity changes in seismically active areas were identified.