WRAPUP 11-Hurricane Ike menaces vulnerable Texas coast

*Ike expected to make landfall within hours

*Storm could flood 100,000 homes

*More than 20 percent of US refining capacity shut down

By Chris Baltimore

HOUSTON, Sept 12 (Reuters) - Hurricane Ike roared toward the Texas coast on Friday, threatening to drive a 20-foot (6-metre) wall of water into coastal communities and menacing Houston, the fourth-largest U.S. city.

The enormous hurricane, roughly the size of Texas itself, may be the worst storm to hit the state in nearly 50 years and is likely to make landfall within hours, the National Hurricane Center said.

High winds and rain from the storm's outer bands lashed the coast, sending huge waves crashing against a 17-foot (5-meter) sea wall built to protect Galveston, a barrier island city, after a hurricane there in 1900 killed at least 8,000.

The storm shut down 17 oil refineries, totaling more than a fifth of U.S. production, endangered a freighter at sea, and destroyed a pier in Galveston.

The National Weather Service warned that people in coastal areas could "face the possibility of death" and officials said the enormous storm could flood as many as 100,000 homes and send a huge wave across 100 miles (160 km) of U.S. coastline.

"Our nation is facing what is by any means a potentially catastrophic hurricane," said U.S. Homeland Security Secretary Michael Chertoff, warning that the storm surge could present the gravest danger.

Nearly a million Texans heeded evacuation orders and headed inland, but officials said they were worried that many people had stayed in their homes.

"We don't know what we're going to find tomorrow," Galveston's mayor Lyda Ann Thomas told the Houston Chronicle. "We hope we'll find that the people who didn't leave here are alive and well."

Ike was a Category 2 storm with 110 mph (175 kph) winds, and could easily become a Category 3 hurricane on the five-step intensity scale with winds of more than 111 mph (178 kph).

Forecasters warned the storm would send water surging up the Houston Ship Canal, the second busiest U.S. port and that strong winds could heavily damage the glass-laden skyscrapers that dot Houston's skyline.

Ike also forced waters inland and up a network of bayous that weave through the city, threatening to inundate neighborhoods.

At 10 p.m. CDT (0300 GMT), the storm was about 55 miles (85 km) south-southeast of Galveston and moving northwest at 12 mph (19 kph), the center said.