"Galveston is a barrier island, a narrow landmass made mostly of sand that extends along a coastline parallel to the land. These islands, common along the Gulf Coast and East Coast of the United States, are some of the most fragile and changing landforms on Earth.
Barrier islands like Galveston are particularly vulnerable to storm damage because they are made of sand, as opposed to the hard bedrock that underlies larger islands and the mainland. They also tend to have very low elevations, making it easy for water to wash over and submerge the island. For many people living on barrier islands, there is no amount of structural support that can ward off the worst.
The eastern part of Galveston Island (also the more densely inhabited) has a strong 18-foot sea wall in place to deflect some of the incoming waves, so it should be more protected than the western half, depending on the extent to which the storm surge overtops the wall.
Many have questioned the wisdom of choosing to build on and develop barrier islands, given their risks."