ST. JOHN'S, Montserrat (AP) _ Staying close to their radios, thousands of islanders nervously awaited Friday a double whammy _ a possible volcanic eruption and the more certain onslaught of a violent tropical storm.

For the first time since Montserrat's centuries-dormant volcano rumbled to life July 18, the government urged people to get off the 7-by-11-mile island if they had anywhere to go.

Tropical Storm Iris was approaching from the east. The center was expected to hit the island Friday night, with sustained winds of 65 mph and gusts to hurricane force.

A separate tropical squall hit the island late Thursday. At a tent city inhabited by 700 evacuees, gusting winds wrenched corrugated iron sheeting from shower stalls and the kitchen and sent them crashing into the U.S. military-issue tents. Other tents were blown over and several children were separated from their parents in the chaos.

Two-thirds of the British colony's 12,000 residents have been evacuated from the southern half of the island since the Soufriere Hills volcano blew a column of ash, steam and noxious gases 7,000 feet into the air on Monday, said Gov. Frank Savage.

The ashes inundated Plymouth, plunging the capital into darkness for half an hour.

The volcano's behavior indicated there was a 70 percent to 80 percent chance of a ``violent eruption that may threaten the lives of the population,'' the U.S. Geological Survey reported this week.

More than 1,500 people flew to neighboring island-nations Wednesday and Thursday. Those left behind either went to the tent camp or moved in with friends and relatives.

``We're encouraging people who have families on neighboring islands to leave the island,'' said National Disaster Coordinator Juliette Brade, speaking to reporters Friday at a school-turned-hospital.

``If we were dealing with just a volcano, it would be fine. Now we're dealing with maybe a hurricane and the planning is different,'' she said.

The islanders anxiously followed radio reports on the progress of Tropical Storm Iris, downgraded from a hurricane, as it moved closer to the Caribbean.

The U.S. National Hurricane Center posted a tropical storm watch for all the islands in the Caribbean's Lesser Antilles: Antigua and Barbuda, Barbados, Grenada, Martinique, St. Maarten, St. Martin, St. Vincent and the Grenadines, Anguilla, Guadeloupe, Dominica, St. Lucia, and St. Kitts.

The center said the center of the storm would strike Friday night with sustained winds of 65 mph, with gusts to hurricane force.