Large-scale map of flow field

This map shows recent changes to Kīlauea's active East Rift Zone lava flow field. The area of the flow field on March 25 is shown in pink, while widening and advancement of the flow field as mapped on May 9 is shown in red. The yellow lines show the mapped portion of the active lava tube system. Pu‘u ‘Ō‘ō lava flows erupted prior to June 27, 2014, are shown in gray. Pu‘u ‘Ō‘ō is at lower left.

The blue lines show steepest-descent paths calculated from a 1983 digital elevation model (DEM; for calculation details, see http://pubs.usgs.gov/of/2007/1264/). Steepest-descent path analysis is based on the assumption that the DEM perfectly represents the earth's surface. DEMs, however, are not perfect, so the blue lines on this map can be used to infer only approximate flow paths. The base map is a partly transparent 1:24,000-scale USGS digital topographic map draped over a 1983 10-m digital elevation model (DEM).