KUALA LUMPUR, Malaysia — Australia announced on Friday that it had moved the search area for Malaysia Airlines Flight 370 nearly 700 miles to the northeast, the latest in a long series of changes by the authorities on where they think the plane might have disappeared.

The authority said it was acting after further analysis of radar data from when the plane, which was supposed to be flying from Kuala Lumpur to Beijing, instead turned over the South China Sea and flew back over Peninsular Malaysia. The analysis showed that the aircraft was moving faster than previously estimated and so would have used more fuel.

That in turn would mean that the aircraft could have run out of fuel sooner as it flew out over the southern Indian Ocean, according to the Australian Maritime Safety Authority.

“This is a credible new lead and will be thoroughly investigated today,” Prime Minister Tony Abbott of Australia said in a statement on Friday morning, adding that 10 aircraft, six vessels and various satellites would focus on the new search area.

Mikael Robertsson, a co-founder of Flightradar24, an aviation tracking firm based in Stockholm, said that the unusual speed of the aircraft over peninsular Malaysia following its turnaround over the South China Sea could be explained either as an attempt by pilots to race to a runway to land the plane in response to an aircraft malfunction or else as part of an effort to hide from the authorities.

“Either they wanted to land very fast or they wanted to escape radar coverage as soon as possible,” he said. “You burn a lot more fuel when you fly very fast, so normally you try to avoid it.”

The revision of the search area, based on further analysis by an international team of experts working with Malaysian officials, means that Australia is redirecting the search far from the floating objects seen in the previous search area in satellite images released by Australia, China and the European satellite launch company Airbus Defense and Space.

Those objects were in or very near the previous search area, as satellite operators had trained their cameras there.

At 123,000 square miles, or 319,000 square kilometers, the new area is about the size of New Mexico and is only one-fifth of the size of the previous search area. John Young, the director general of the Maritime Safety Authority, said at a news conference near Canberra on Friday that the ocean is 2,000 to 4,000 meters deep in the new search area, or 6,500 to 13,000 feet, making it shallower in some places than the previous search area.

Mr. Young also said at the news conference that the weather in the new search area should be considerably better than that of the zone previously searched.

The new zone is 1,150 miles west-southwest of Perth, Australia, closer to Perth than the previous zone, shortening the flight for surveillance aircraft by up to an hour in each direction and allowing aircrews to spend more time actually looking for debris from Flight 370.

“It is a different ballpark,” said Erik van Sebille, an oceanographer of New South Wales University, of the new search area. “Where they are searching now is more like a subtropical ocean. It is not nearly as bad as the southern Indian Ocean, which should make the search easier.”

“The water in this area is more like the oceans around the Bahamas,” Dr. van Sebille added. But he also warned that the seabed in the area is marked by a steep ridge and that prevailing currents drag in more debris from other parts of the ocean.

“It may be harder to spot from the air the debris related to the plane because there is more garbage floating in this area,” he said.