30 percent of Galveston 's population evacuated the island when Hurricane Allen threatened the eastern Texas coastline in 1980 ; only 10 percent of the population living behind the seawall chose to leave when Alicia made landfall . ( About 30 percent of Galveston 's population evacuated the island when Hurricane Allen threatened the eastern Texas coastline in 1980 ; only 10 percent of the population living behind the seawall chose to leave when Alicia came ashore . )