Sidescan sonar image of a portion of the insular shelf off Luquillo showing a channel cutting across the eolianite ridges partially filled with sediment. USGS marine geologists examined coral reef complexes around Culebra Island affected by Hurricane Hugo. The shelf area offshore the town of Luquillo was mapped using Divers examined and photographed reefs around Culebra Island, drilled deep cores to determine the geologic history of the reefs, and took cores from individual living corals to study growth rates and to evaluate the effect of Hugo and of previous storms. In spite of the devastation, the reefs on the east side of Culebra are showing signs of healthy regrowth. The geological evidence suggests that high-energy storms may be necessary for healthy growth of coral reef complexes in the same way fire is necessary for healthy forest growth.
North is to the left.
Understanding the ability of coastal environments to recover from effects of storms requires high-quality scientific data. From a geological perspective, hurricanes often accomplish less modification to coastal environments than do other high-energy events because the hurricane passes quickly. Geological evidence suggests that sand and gravel resources may be lost as a result of storm action. An understanding of the sediment budget for an area depends on geologists' ability to track movement of sediment and to map the seafloor in detail. For example, early suggestions that sand and gravel off Luquillo were lost off the shelf into the deep ocean during a storm were rejected after detailed mapping indicated that other geological factors intervened.