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Tales of the Coast
Coastal Dynamics

Waves and Volcanic Coasts

Waves can have various effects on volcanic coasts, depending on the type of volcanic sediment present at the shore.

Shoreline erodability along volcanic coasts ranges from very erodible for ash and unconsolidated sediment to very resistant for basalt. In the Aleutian Arc, lava and mudflows from volcanic eruptions have buried the coast, and the deposits are quickly reworked by waves. In contrast, the basalt masses of the Hawaiian Islands are very resistant to wave erosion.

On the Big Island of Hawaii, sea cliffs are about 10 m high and have been notched or undercut by the surf. Small, steep pocket beaches consisting of black volcanic sands have developed in some notches. Throughout Hawaii, many beaches are undergoing serious erosion, and finding suitable sources of sand for renourishment has been difficult.

Volcano
Source:National Parks Service

Waves and Volcanic Coasts

Hawaiian Coast: Because of the harsh wave climate and tectonic instability, coastal engineering in the Hawaiian Islands is particularly challenging.