A powerful 6.4 magnitude earthquake hit San Juan Province in Argentina late Monday night, according to early reports from the U.S. Geological Survey.  A series of aftershocks, with a lower magnitude than the quake also occurred.  The U.S. Tsunami Warning System said the earthquake in west central Argentina did not pose a tsunami threat and no warning was posted.  Initial reports indicate the quake, which hit at a shallow depth of 10 kilometers beneath the epicenter near Pocito, Argentina, had the potential to damage buildings and infrastructure, but there were no immediate reports of widespread damage.  
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