Hazards

Volcano and earthquake hazards occur regularly in Hawaii.

The earthquake hazard in the State of Hawaii is among the highest in the United States. The south side of the Island of Hawai‘i is under the greatest threat, as evidenced by the three largest earthquakesthat occurred there since 1868.

Hawaiian volcanoes have produced explosive eruptions ranging in size and vigor from relatively small lava fountains to large eruptions.

Ground fractures and subsidence hazards Hawai‘i.

Lava entering the ocean creates a distinctive set of hazards that have seriously injured or killed unsuspecting people eager to see up close the interaction of hot lava and cool seawater.

Lava flows on the Island of Hawai‘i are renowned for their frequent occurrence, relatively easy access, land-building ocean entries, and for Hawaiian names that describe their surface textures—rubbly ‘a‘ā or smooth and sometimes ropey pāhoehoe.

Volcanic gas emissions are composed mainly of water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2) gas, with trace amounts of several other gaseous compounds, including hydrogen sulfide (H2S), hydrogen fluoride (HF), and carbon monoxide (CO). The chief gas hazard in Hawai‘i results from SO2 gas.

Residents of Hawaii are accustomed to feeling earthquake shaking. The magnitude, location, and depth of an earthquake, and overlying soil conditions determine how widely and strongly any particular event can be felt. Typically, people report feeling earthquakes larger than about magnitude 3.0.

Thousands of earthquakes occur every year in the State of Hawaii. They are caused by eruptive processes within the active volcanoes or by deep structural adjustments due to the weight of the islands on Earth's underlying crust.