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Chapter 8:Hazard Analysis—Lava and VOG <br /> 8.1.2 VOG <br /> "VOG,"coined from "volcanic smog"but standing for"Volcanic Gas", is a term used by the <br /> public in Hawaii to describe hazy conditions caused by gaseous emissions from Kilauea <br /> volcano. Vog is created when Volcanic Gases (primarily oxides of sulfur, S02)react with <br /> sunlight, oxygen and moisture. The result includes sulphuric acid and other sulfates. VOG is <br /> made up of a mixture of gases and aerosols which makes it hard to study and potentially <br /> more dangerous than either on their own. The S02 gas in VOG is greater near the sources <br /> (Halema`uma`u and Pu`u `O`o vents). S02 levels are lessened further away or upwind from <br /> the vents. Vog mostly affects the Kona coast on the west side of the island of Hawaii,where <br /> the prevailing trade winds blow the vog to the southwest and southern winds then blow it <br /> north up the Kohala coast. The haze caused by vog may be heavy in West Hawaii, but the <br /> S02 levels are typically lower due to the geographic distance from the sources. One cannot <br /> judge the amount of S02 in the air or its danger to humans and plants by how heavy the vog <br /> appears, S02 levels can be high with only light vog. <br /> 11*61 <br /> a <br /> .r <br /> ,LL <br /> Figure 8-1. Volcanic Gas Emissions at Kilauea Volcano's Summit Vent on May,2009 <br /> 8-2 Hawaii County Multi-Hazard Mitigation Plan <br />