A mysterious sonic boom ratttled part of the Eastern seaboard Thursday afternoon, being felt from southern New Jersey to Long Island, the United States Geological Survey confirmed on Twitter. It was not immediately clear what caused the boom, but some initially believed that it was an earthquake.

The boom was centered north of Hammontown, NJ, around 1:30 p.m. It was the first of nine booms reported in southern New Jersey and along the Eastern Seaboard to Long Island, New York in the hours following the initial boom, the USGS said. The National Weather Service in Mount Holly said it contacted researchers at Columbia University who confirmed that the trembling was not an earthquake. FULL REPORT