About this map:

This map shows the extent of the contour line that corresponds to the zero elevation of the boundary surface between basement volcanic units and overlying limestone units in northern Guam. The source of the geospatial information is the 2013 volcanic basement map, an update of the original 1982 map produced by the Northern Guam Lens Study (CDM, 1982). The work on updating the map utilized geophysical and drilling data to correct and refine the understanding of basement topography and improve the map; see WERI Technical Report #141 (Bendixson, 2013). Details on the methodology used, content, and applications of the map can be found in WERI Technical Report #142 (Vann et al., 2013).