( CNN ) -- A strong 6.6-magnitude earthquake struck Sunday off the coast of Antarctica , prompting a warning that there was a `` small possibility '' it could trigger a tsunami . The tremor was centered in waters south of South America 's southern tip , about 334 miles ( 539 kilometers ) west of Coronation Island and 388 miles northeast of Palmer Station in Antarctica , the U.S. Geological Survey reported . It hit at 9:40 a.m. local time ( 8:40 a.m . ET ) on Sunday , according to the federal agency , and had an estimated depth of 6.2 miles . Afterward , the Pacific Tsunami Warning Center released a statement saying that there appears to be no threat of `` destructive widespread tsunami '' because of the quake . But the agency did state `` there is a small possibility of a local or regional tsunami that could affect coasts located usually no more than a few hundred kilometers from the earthquake epicenter . `` Authorities in the region near the epicenter should be made aware of this possibility , '' the warning center added .
The storm struck Sunday morning near Scotland 's Shetland Islands . The USGS estimates it struck at a depth of 10 km . A U.S. agency warns there 's a ` ` small possibility of a ... regional outbreak ''