#Sulphur Cone

Ta‘ū volcano in American Samoa experienced volcanic unrest in the form of an earthquake swarm that was felt throughout the Manuʻa Islands (Ofu-Olosega and Ta‘ū Islands) from late July through early September 2022.

Disturbances to a magma or lava body—such as Kīlauea Volcano’s underground summit magma reservoir or its current lava lake—can occur for a variety of reasons, including rising gas pockets or the fall of wall rocks into a lava lake. When a body of magma or lava is disturbed, the fluid in it can respond by vibrating or sloshing in a variety of ways.

The original purpose of geologic mapping in Hawaiʻi was to understand the distribution of groundwater and soils to support agriculture. But as geologic maps have been developed over time, they’ve provided basic information on how the Hawaiian Islands evolved, the workings of individual volcanoes, and the relative degree of long-term hazards posed.

Olivine crystals—the beautiful green mineral common in Hawaiian lavas—record when and where magmas move inside Hawaiian volcanoes before they erupt. We can actually use these little crystals like clocks to better understand the magmatic events leading to the December 2020 and September 2021 summit eruptions at Kīlauea.