Now Shield volcanoes, built almost entirely of lava flows, occur at mid-ocean ridges and hot spots. They have gentle topographic profiles and the lava is fluid. Lava fountains and flows may be spectacular. The Hawaiian shield volcanoes threaten sensitive coastal ecosystems, transportation and communication networks, and populated regions. Volcanic emissions are of interest to NOAA scientists who study the atmosphere.
Underwater volcanoes heat the ocean and change the sea floor topography.
These changes can cause the global sea level to rise and affect weather patterns. Tsunamis caused by debris avalanches pose a threat to the Hawaiian coast.