"Distributed volcanic fields" are so named because they contain many small volcanoes scattered over a large area instead of a central vent. These volcanoes are often – but not always - small "one-and-done" eruptions which erupt once and then never again.  Springerville volcanic field (SVF), Arizona, is a distributed volcanic field that covers about 3000 km 2 (1,160 mi 2 ) and has at least 405 vents in the form of fissures, cones, and maar craters (see photo of the Cerro Hueco maar crater below).  Cerro Hueco maar crater: a giant hole blasted though preexisting rocks by magma explosively interacting with groundwater. The gently-sloping cone surrounding the crater was formed by layers of debris piling up over the course of the eruption. Three people are standing on the crater rim for scale. USGS photo by Dawnika Blatter. The SVF is one of seven distributed volcanic fields found along the margin between  the Colorado Plateau and the Basin and Range.…