Sonntag, Apr 14, 2013
A cluster of earthquakes has occurred during the past days under the caldera. USGS reports: ... [mehr]
Newberry VulkanNewberry volcano east of the Cascade Range in Oregon, is one of the largest volcanoes on the US mainland. It covers about 1600 km2 and contains a large caldera, Newberry Crater, that was created several 100,000 years ago by a series of devastating eruptions.
The volcano last erupted about 1300 years ago, blasting a plug of viscous lava and creating the well-known "Big Obsidian Flow."
Beschreibung:The 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