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The plate tectonics concept has dramatically changed the understanding about the Earth's phenomena since the 1960s. But do we understand correctly the concept? We try to address the problem of plate motion direction using seismological evidences. We emphasize the proofs of a southward component of motion for central Eurasian plate, which has not been addressed in any other plate motion model. The question first arose following a M6.7 earthquake on Feb. the 4th, 1997 in northeast Iran. Based on the aftershocks distribution relative to the surface rupture trace we concluded that the Turan block, which is part of the Eurasian plate, should have a southward component of motion directed towards Iran. This was in odds with the common belief that Turan block was fixed and that the geological structures in northeastern Iran were regarded as resulting from compression of Iranian sub-plate to Eurasia. The aftershocks distribution of the M7.4 earthquake on June 20th, 1990 in northern Iran supports the idea of existence of a southward component of motion for Eurasian plate. Although the concept of relative plate motion is mathematically correct, it is sometimes mis-interpreted and consequently it will be confusing. In order to prevent this confusion, it seems necessary to derive the absolute plate motion vectors using additional constraints. The same confusion but in smaller scales, which roots from the mis-interpretation of Newton's third law, is observed in other branches of the Earth sciences, like seismology and structural geology.
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