DUBAI, United Arab Emirates—A fiery explosion erupted on a container ship anchored in Dubai at one of the world’s largest ports late Wednesday, authorities said, sending tremors across the commercial hub of the United Arab Emirates. There were no immediate reports of casualties, and it was unclear what triggered the blast. The blaze sent up giant orange flames from a vessel at the Jebel Ali Port, the busiest in the Middle East. Jebel Ali sits on the eastern side of the Arabian Peninsula and is also the busiest port of call for American warships outside the United States. The combustion unleashed a shock wave through the city of Dubai, causing walls and windows to shake in neighborhoods as far as 25 kilometers (15 miles) away from the port. Residents filmed from their high-rises as a fiery ball illuminated the night sky. The blast was powerful enough to be seen from …