1. A method for detecting whether an object is buried beneath a target surface area of the ground, comprising: 1) in a first cycle: a) capturing a first infrared image of the target surface area indicative of a first initial temperature distribution thereon; b) directing a microwave signal of a first frequency at the target surface area and capturing a second infrared image of the target surface area indicative of a first heated temperature distribution thereon; and c) subtracting the first infrared image from the second infrared image to form a first temperature rise image; 2) in a second cycle: a) directing a microwave signal of a second frequency at the target surface area and capturing a third infrared image of the target surface area indicative of a second heated temperature distribution thereon, the second frequency differing from the first frequency by an amount effective to yield an acceptably high signal to noise ratio in a difference image to be calculated as part of the method; and b) subtracting a fourth infrared image from the third infrared image to form a second temperature rise image, the fourth infrared image being indicative of a second initial temperature distribution of the target surface area at the beginning of the second cycle; and 3) subtracting the first temperature rise image from the second temperature rise image to obtain the difference image for processing to identify characteristics indicative of the presence of a buried object.