A method for monitoring an area that involves transmitting a first electromagnetic wave signal from a mobile platform moving over a ground surface, toward the ground surface. A receiver is used that is located remote from the mobile platform to receive the first electromagnetic wave signal after the signal is reflected from the ground surface. The first electromagnetic wave signal is processed to form a first synthetic aperture radar (SAR) image. Subsequently the receiver is used to receive a second electromagnetic wave signal transmitted from the mobile platform at a time subsequent to transmission of the first electromagnetic wave signal. The second electromagnetic wave signal is then processed to obtain a second SAR image. The first and second SAR images are then coherently analyzed to determine areas of non-correlation between the images.