IntroductionThe low-angle basaltic to basaltic-andesite shield volcano is dotted with more than 400 cinder cones, and most of its edifice is the result of voluminous lava flows. However, Newberry volcano has also produced major explosive silicic eruptions, which formed the 6 x 8 km wide summit caldera containing two caldera lakes.
The earliest eruptive products (<0.73 million years ago) (Ma) consist of a sequence of ash-flow and airfall tuffs. Caldera collapse is thought to be associated with 2 major ash flows emplaced about 0.5 and 0.3-0.5 Ma, respectively. These eruptions were preceded by the emplacement of numerous basaltic cones and vents and silicic lava domes and flows, many of which are aligned NNW and NNE parallel to regional fault zones.
A rhyolitic magma chamber has been present throughout the past 10,000 years. 6 major eruptive episodes within the past 10,000 years until about 1300 years ago have included both the eruption of basaltic lava flows from flank vents and the explosive ejection of rhyolitic pumice and pyroclastic flows and the extrusion of obsidian flows within the caldera.
Source: GVP Newberry volcano information
See also: Sentinel hub | Landsat 8