Hundreds of North Jersey and Eastern Pennsylvania residents reported hearing a loud explosion Wednesday afternoon around 12:30. I saw several Facebook posts myself but didn't hear anything. A few videos posted on the Sussex County What's Happening page confirm the loud noise. More than 600 comments were made on the forum "Volcano Discover" which theorize the "boom" could have come from seismic activity near Parsippany. A quarry in Rockaway Township says they caused a small blast around 10:30. Picatinny Arsenal says some ammunition was destroyed around 2:30 PM. Which could have caused a booming sound in the area. The timing of both these events doesn't come close to when the widespread boom was heard around 12:30. The New Jersey State Police say they didn't get any calls about a loud explosion on Wednesday. So the cause of what people say they heard remains a mystery.