The Bam area has an underground base consisting of a series of faults. The main one, called Bam Fault, had been inactive for a very long time. Though the earthquake was on the southern part of Bam, the main direction of the horizontal motion of the waves was East-West and was perpendicular to the direction of the main fault located around 3 km East of Bam. It seems that the Bam Fault channeled the energy of the earthquake in its direction, North-South, but at the same time, it acted like a boomerang or amplifier by sending back the energy on an East-West direction.