Nine fairly strong earthquakes, all registering 4 on the 7-point Japanese intensity scale, jolted the islands of Niijima, Kozu, and Miyake in the Izu chain Monday, the Meteorological Agency said.

There were no immediate reports of casualties or damage caused by the quakes, which struck between 4:42 a.m. and 1:00 p.m.

The focus of the strongest quake, at 5:03 a.m., which had a magnitude of 5.4, was located about 10 km below the seabed off Miyake, a small volcanic island some 180 km south of Tokyo.

The quake registered 3 on the Japanese intensity scale on Izu-Oshima Island, also in the Izu chain, and 2 in Yokohama, Suwa, Nagano Prefecture, and Mishima, Shizuoka Prefecture.

The quake was felt in a wide area of eastern Japan, including the Tokyo metropolitan area and Niigata, Nagano, and Shizuoka prefectures.

The agency issued a warning that the Izu islands may be jolted by more quakes with an intensity of 5 on the Japanese intensity scale.

In Kozu, which Saturday was hit by a powerful quake measuring lower 6 on the Japanese scale, restoration efforts are under way, with the island’s water supply expected to be restored Monday. One islander was killed in the quake.

However, aftershocks are hampering efforts to repair roads damaged by the temblor.

A local official of Kozu village said, “I’m worried about another earthquake and heavy rain, because irrigation channels for agricultural use are still out of use.”

Miyake schools open

Classes resumed Monday at Miyake Island’s six elementary and junior high schools, after seven days of temporary closure caused by the threat of a volcanic eruption on the island.

Life on Miyake Island is gradually returning to normal, despite continuous earthquakes and a disrupted water supply for some of the schools.

On June 26, after the number and intensity of volcanic earthquakes had increased rapidly, evacuation orders were issued for parts of the island, notably the Ako and Tsubota districts, which have four junior high schools.

Classes in the Miyake elementary school and Miyake junior high school, which are not in areas evacuated, were also affected because the schools were used as evacuation shelters.

Although the evacuation alert was lifted Thursday, some places, especially in the Ako district, still have no water supply because of earthquake-related damage.

Students and teachers at elementary and junior high schools in Ako resumed classes Monday and were supplied by water tanker.