Approaches to electromagnetic monitoring of variations in apparent resistivity and electromagnetic emission in the ULF-ELF ranges before earthquakes are considered. Variations in apparent resistivity, determined from measurements of natural electromagnetic fields, should be studied in the frequency range of 7-300 Hz, and at lower frequencies, it is advisable to analyze the behavior of the components of the electrotelluric and magnetic fields. Results of studies on the identification of active faults and the search for stress-strain sensitive places for the installation of equipment using data on the registration of tidal variations in apparent resistivity are presented. Based on the analysis of monitoring data in China, possible sources of electromagnetic emission recorded before the Yangbi earthquake (March 27, 2017, M5.1) are considered.