A powerful 8.0 magnitude earthquake caused a tsunami that sent strong waves crashing into several South Pacific islands on Wednesday, with officials in the Solomon Islands saying that at least four people died.

The earthquake prompted tsunami warnings and watches from several island chains to Australia and later New Zealand, but many were later canceled.

The low-lying Solomon Islands, however, were not spared. At least 100 homes in the town of Lata were destroyed by a surge of water, according to World Vision, a Christian humanitarian organization. Water and electricity also remained out in the town, which is the capital of the Solomon Islands’s Temoto Province.

Government officials said that in addition to the four confirmed deaths in the islands, there were unconfirmed reports that some people in fishing boats were swept out to sea.

The majority of Lata’s residents relocated to higher ground in central Lata, following many who fled before the surge. Even though the tsunami warning for the region was lifted, significant tremors were still being felt throughout Temotu Province and waters had not fully receded late in the day.

The Pacific Tsunami Warning Center said the tsunami warning was limited to the Solomon Islands, Vanuatu, Nauru, Papua New Guinea, Tuvalu, New Caledonia, Kosrae, Fiji, Kiribati, and Wallis and Futuna.

A lesser alert, a tsunami watch, was declared for American Samoa, Australia, Guam, the Northern Marianas, New Zealand and eastern Indonesia.

The earthquake was not only powerful but also shallow, which gave it significant potential to cause damage, said Barry Hirshorn, a geophysicist with the National Weather Service in Hawaii. Moreover, it was a thrust earthquake, he said, meaning that the seafloor moved up or down, not sideways, contributing to the potential for a dangerous tsunami.

But after the earthquake, as scientists watched to see how far a tsunami might spread, there were few early indications of a major threat beyond the immediate area, Mr. Hirshorn said. A water rise of about three feet had been observed close to the earthquake, he said, still high enough to be potentially damaging but probably not big enough to threaten distant shores.

In New Zealand, thousands of people were at the beach, swimming in the sea on a glorious summer afternoon on Waitangi Day, a national holiday — quite oblivious to the potential for a tsunami. Tsunami sirens were set off late in the afternoon there, and people in coastal areas were being told to stay off beaches and out of the sea, rivers and estuaries.

The New Zealand Herald reported Wednesday afternoon on its Web site that tsunami sirens in Suva, the capital of Fiji, had been warning people to stay inside or go to higher ground.