A supertanker gashed its hull near the country’s busiest port Wednesday and dumped about 390,000 gallons of light crude that drifted toward rich fishing grounds.
Japanese officials today drastically reduced their earlier estimates of the amount of oil spilled by the ship in Tokyo Bay. They initially placed the figure at nearly 4 million gallons.
Maritime Safety Agency spokesman Masami Suda said authorities changed the estimate because a tank they had thought ruptured when the Diamond Grace ran aground south of Tokyo on Wednesday was found to be intact.
By early this morning, the 11-mile-wide slick had reached land in three places along the industrial shoreline of Yokohama and Kawasaki just south of Tokyo. More than a dozen people - mostly children - were sickened by the fumes.
Authorities feared the widening slick could also reach coastal fishing areas in the northern part of Tokyo Bay and on the Chiba peninsula on the bay’s eastern side.
“The most important thing for us to do now is to limit the extent of the spill,” said Shigehiro Sakamoto, head of the cleanup crew. “We are putting all of our resources into that.”
The 147,012-ton, Panamanian-registered Diamond Grace ran aground Wednesday morning about 22 miles south of Tokyo, not far from Yokohama, Japan’s busiest port.
The leaking stopped 1-1/2 hours after the accident, and the black-and-white cigar-shaped vessel, sitting low in the water, moved to nearby Kawasaki to be emptied of its shipment.
Investigators were trying to determine what the single-hulled tanker had struck. Kyodo News agency reported it had scraped a reef in shallow waters in the middle of Tokyo Bay, tearing holes in an oil tank near the starboard bow.
The government said both the vessel’s oil storage tanks had sustained damage but later announced that only one had been gashed.
More than 100 ships have been mobilized to clean up the spill and slow the oil’s advance north. Workers spread absorbent mats on the slick or scooped it up with barrels, buckets and ladles, and helicopters sprayed dissolving agents on it.
Japan’s worst oil spill occurred in 1974, when 2 million gallons poured from a storage tank in southwestern Japan.
Wednesday’s spill was the second major oil accident this year in Japan. In January, a Russian tanker split and sank in the Sea of Japan, spilling 1.2 million gallons of fuel oil and fouling hundreds of miles of shoreline.
Nearly 60 tankers a week crisscross this busy harbor, providing the fuel for the 26 million residents of this supercity. Experts expressed surprise that a tanker could run aground in an shipping channel so thoroughly charted, and the Kyodo News Agency quoted Maritime Safety officials as saying the incident may have been caused by mismanagement by the tanker’s captain, Hidenori Tsunematsu.
Investigators questioned him as to why the single-hulled tanker entered a shallow sea lane, where the water is only 40 to 55 feet deep. A tanker ran aground near there in 1975.
It was not clear how the slick would affect life in Tokyo itself and neighboring Chiba - home to nearly 18 million people. Fifteen people who lived near the bay, including 13 children, were sickened by the strong odor Wednesday and hospitalized.
The greatest immediate threat seemed to be to the bay’s fishing grounds. Yokohama port is heavily industrialized and oil storage facilities dot the coastline, but towns that depend on the bay’s fish - which help feed Japan’s largest metropolitan area - ring the bay as well.