Isolated cases of flu and diarrhea have broken out in an evacuation center for villagers ordered from their homes after a volcano began erupting on this remote South Pacific island, officials said Sunday.

Morris Harrison, a Vanuatu geophysicist, said low-level earthquakes continued to shake Ambae Island, "and if they continue or increase in size we will be worried."

Several thousand people were evacuated last weekend after Mout Manaro began spewing steam, sulfur gas and ash up to 10,000 feet above this island of 10,000 villagers in northern Vanuatu.

Across camps holding 5,000 people "there are no major illnesses," acting provincial health director Hope Leodoro told The Associated Press. "We have a report from Londua Center in West Ambae of flu and diarrhea. But after checking with the health nurse at the center there are not many people with these diseases," he said.

He said evacuees generally were healthy.

The volcano's seismic activity has remained largely stable since Dec. 4, when monitoring began, Harrison said. After a 10-year slumber, Mount Manaro been pumping steam and ash on Nov. 27.

Scientists are to hike to the volcano rim Monday to check reports that two vents have now formed in the crater lake — and that new ash islands are emerging from the muddy, toxic waters of the once blue Lake Vui.

Villagers accustomed to huts built from palm fronds and sheets of tin in the cool jungles on the volcano's flanks are now crowded into hot concrete block buildings close to the shore.

Leodoro said the island's dispensaries have enough drugs to last three weeks, with more expected on Monday from stocks on nearby Santo Island and from the capital, Port Vila.

Hospitals on the island, cleared of patients when the emergency began, remain empty but staffed by surgeons and other medical staff in case the volcano explodes or unleashes a devastating mud flow.

Ambae lies in northern Vanuatu, an 80-island archipelago 1,400 miles northeast of Sydney, Australia, that is said to be the inspiration for the idyllic Bali Hai in James Michener's "Tales of the South Pacific."