The post-Mazama northwest rift zone eruption at Newberry Volcano, Oregon
The post-Mazama northwest rift zone eruption at Newberry Volcano, Oregon (in Volcanoes to vineyards; geologic field trips through the dynamic landscape of the Pacific Northwest, Jim E. O'Connor (editor), Rebecca J. Dorsey (editor) and Ian P. Madin (editor))
Field Guide (Geological Society of America) (December 2009) 15: 91-110
- Cascade Range
- Cenozoic
- Deschutes County Oregon
- eruptions
- geochemistry
- geologic hazards
- hawaiian-type eruptions
- Holocene
- igneous rocks
- lapilli
- lava flows
- lower Holocene
- major elements
- Newberry Volcano
- Oregon
- pyroclastics
- Quaternary
- review
- rift zones
- scoria
- strombolian-type eruptions
- trace elements
- United States
- vents
- volcanic ash
- volcanic risk
- volcanic rocks
- volcanism
- volcanoes
The northwest rift zone (NWRZ) eruption took place at Newberry Volcano approximately 7000 years ago after the volcano was mantled by tephra from the catastrophic eruption that destroyed Mount Mazama and produced the Crater Lake caldera. The NWRZ eruption produced multiple lava flows from a variety of vents including cinder cones, spatter vents, and fissures, possibly in more than one episode. Eruptive behaviors ranged from energetic Strombolian, which produced significant tephra plumes, to low-energy Hawaiian-style. This paper summarizes and in part reinterprets what is known about the eruption and presents information from new and ongoing studies. Total distance spanned by the eruption is 32 km north-south. The northernmost flow of the NWRZ blocked the Deschutes River upstream from the city of Bend, Oregon, and changed the course of the river. Renewed mafic activity in the region, particularly eruptions such as the NWRZ with tephra plumes and multiple lava flows from many vents, would have significant impacts for the residents of Bend and other central Oregon communities.
