Publications
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Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon
The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks
Authors
Mark L. Ferns, Martin J. Streck, Jason D. McClaughry
Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon
Crater Lake partly fills one of the most spectacular calderas of the world—an 8 by 10 kilometer (km) basin more than 1 km deep formed by collapse of the Mount Mazama volcano during a rapid series of explosive eruptions ~7,700 years ago. Having a maximum depth of 594 meters (m), Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 squar
Authors
Charles R. Bacon, Heather M. Wright
Oxygen and U-Th isotopes and the timescales of hydrothermal exchange and melting in granitoid wall rocks at Mount Mazama, Crater Lake, Oregon
We report new whole rock U-Th and in-situ oxygen isotope compositions for partially melted (0–50 vol% melt), low-δ18O Pleistocene granitoid blocks ejected during the ∼7.7 ka caldera-forming eruption of Mt. Mazama (Crater Lake, Oregon). The blocks are interpreted to represent wall rocks of the climactic magma chamber that, prior to eruption, experienced variable amounts of exchange with meteoric hy
Authors
Meagan E. Ankney, Charles R. Bacon, John W. Valley, Brian L. Beard, Clark M. Johnson
Field-trip guide to Mount St. Helens, Washington - An overview of the eruptive history and petrology, tephra deposits, 1980 pyroclastic density current deposits, and the crater
This field trip will provide an introduction to several fascinating features of Mount St. Helens. The trip begins with a rigorous hike of about 15 km from the Johnston Ridge Observatory (9 km north-northeast of the crater vent), across the 1980 Pumice Plain, to Windy Ridge (3.6 km northeast of the crater vent) to examine features that document the dynamics and progressive emplacement of pyroclasti
Authors
John S. Pallister, Michael A. Clynne, Heather M. Wright, Alexa R. Van Eaton, James W. Vallance, David R. Sherrod, B. Peter Kokelaar
Field-trip guide to a volcanic transect of the Pacific Northwest
The Pacific Northwest region of the United States provides world-class and historically important examples of a wide variety of volcanic features. This guide is designed to give a broad overview of the region’s diverse volcanism rather than focusing on the results of detailed studies; the reader should consult the reference list for more detailed information on each of the sites, and we have done
Authors
Dennis Geist, John A. Wolff, Karen Harpp
Initial pulse of Siberian Traps sills as the trigger of the end-Permian mass extinction
Mass extinction events are short-lived and characterized by catastrophic biosphere collapse and subsequent reorganization. Their abrupt nature necessitates a similarly short-lived trigger, and large igneous province magmatism is often implicated. However, large igneous provinces are long-lived compared to mass extinctions. Therefore, if large igneous provinces are an effective trigger, a subinterv
Authors
Seth D. Burgess, James D. Muirhead, Samuel A. Bowring
Temporal variation of tectonic tremor activity in southern Taiwan around the 2010 ML6.4 Jiashian Earthquake
Deep tectonic tremor, which is extremely sensitive to small stress variations, could be used to
monitor fault-zone processes during large earthquake cycles and aseismic processes before
large earthquakes. In this study, we develop an algorithm for the automatic detection and
location of tectonic tremor beneath the southern Central Range of Taiwan and examine the
spatio-temporal relationship betwee
Authors
Kevin Chao, Zhigang Peng, Ya-Ju Hsu, Kazushige Obara, Kuo-En Ching, Chunquan Wu, Hsin-Chieh Pu, Peih-Lin Leu, Aaron Wech
Geologic field-trip guide to Long Valley Caldera, California
This guide to the geology of Long Valley Caldera is presented in four parts: (1) An overview of the volcanic geology; (2) a chronological summary of the principal geologic events; (3) a road log with directions and descriptions for 38 field-trip stops; and (4) a summary of the geophysical unrest since 1978 and discussion of its causes. The sequence of stops is arranged as a four-day excursion for
Authors
Wes Hildreth, Judy Fierstein
United States-Chile binational exchange for volcanic risk reduction, 2015—Activities and benefits
In 2015, representatives from the United States and Chile exchanged visits to discuss and share their expertise and experiences dealing with volcano hazards. Communities in both countries are at risk from various volcano hazards. Risks to lives and property posed by these hazards are a function not only of the type and size of future eruptions but also of distances from volcanoes, structural integ
Authors
Thomas C. Pierson, Margaret T. Mangan, Luis E. Lara Pulgar, Álvaro Ramos Amigo
Volcano geodesy in the Cascade arc, USA
Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-b
Authors
Michael P. Poland, Michael Lisowski, Daniel Dzurisin, Rebecca Kramer, Megan McLay, Benjamin Pauk
New insights into the Kawah Ijen hydrothermal system from geophysical data
Volcanoes with crater lakes and/or extensive hydrothermal systems pose significant challenges with respect to monitoring and forecasting eruptions, but they also provide new opportunities to enhance our understanding of magmatic–hydrothermal processes. Their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of m
Authors
Corentin Caudron, G. Mauri, Glyn Williams-Jones, Thomas Lecocq, Devy Kamil Syahbana, Raphael de Plaen, Loic Peiffer, Alain Bernard, Ginette Saracco
The saltiest springs in the Sierra Nevada, California
The five saltiest springs in the Sierra Nevada in California are found between 38.5° and 38.8° N. latitude, on the South Fork American River; on Caples Creek, a tributary of the Silver Fork American River; and on the North Fork Mokelumne River. The springs issue from Cretaceous granitic rocks in the bottoms of these major canyons, between 1,200- and 2,200-m elevation. All of these springs were wel
Authors
James G. Moore, Michael F. Diggles, William C. Evans, Karin Klemic