A method includes introducing a tool into a wellbore lined at least partially with a first casing and a second casing concentrically overlapping a portion of the first casing emitting an acoustic wave from an acoustic source included in the tool causing the first and second casings to vibrate at their respective resonant frequencies, emitting high frequency electromagnetic (EM) energy using the tool that interacts with the first casing to generate a first EM scattered field, emitting low frequency EM energy using the tool, at least a portion of the low frequency EM energy traversing the first casing and interacting with the second casing to generate a second EM scattered field, and analyzing the first and second EM scattered fields to determine a presence of corrosion in at least one of the first and second casings.