TOKYO (AP) _ A moderate earthquake shook a chain of volcanic islands south of Tokyo early Wednesday, but no injuries or damage were reported.

The temblor was part of a series of quakes that rattled the area a day after a volcano again spewed ash on one of the largest of the Izu islands, about 120 miles south of Tokyo.

The magnitude 4.2 earthquake struck at 6:21 a.m. and was centered six miles under the ocean floor near the islands of Niijima and Kozushima in the Izu chain, Japan's Meteorological Agency said.

The quake caused buildings to sway, but no damage or injuries were reported, said Katsuhiro Ishida, a town official on Kozushima.

The Izu chain has been shaken by thousands of quakes since Mt. Oyama, a 2,686-foot volcano on Miyake island, awoke from a 17-year slumber July 9.

On Tuesday, Mount Oyama again spewed ash more than a thousand feet into the air, forcing the island's airport to close temporarily.

On Friday, the volcano shot a cloud of ash five miles high, the fifth and largest eruption since the mountain rumbled back to life.