Feature layer for the Learn tutorial Analyze volcano shelter access in Hawaii.This layer is a copy of the Volcano Lava Flow Hazard Zones by HawaiiStateGIS.The boundaries and classification of lava flow hazard zones on Hawaii Island were first mapped by the US Geological Survey in 1974. This classification scheme divides the island into 18 major zones that are ranked from 1 through 9 based on the probability of coverage by lava flows. The  risk levels are based primarily on the location and frequency of historic eruptions (those for which there are written records or that are known from the oral traditions of the Hawaiians) and the geologic mapping and scientific dating of the old flows from prehistoric eruptions.Much of the USGS work was based on a paper called Geologic Map of the Island of Hawaii by Edward Wolfe and Jean Morris.