Publications
Filter Total Items: 2705
Preliminary volcano-hazard assessment for Aniakchak Volcano, Alaska
Aniakchak is an active volcano located on the Alaska Peninsula 670 kilometers southwest of Anchorage. The volcano consists of a dramatic, 10-kilometer-diameter, 0.5 to 1.0-kilometer-deep caldera that formed during a catastrophic eruption 3,500 years ago. Since then, at least a dozen separate vents within the caldera have erupted, often explosively, to produce lava flows and widespread tephra (ash)
Authors
Christina A. Neal, Robert G. McGimsey, Thomas P. Miller, James R. Riehle, Christopher F. Waythomas
Carbon cycling in boreal wetlands: A comparison of three approaches
Three independent methods were used to measure net ecosystem production (NEP) in four wetlands near Thompson, Manitoba, Canada. The first method calculated NEP by subtracting heterotrophic respiration from net primary productivity, using both measurements and estimates derived from the literature. The second method used radiocarbon data from cores to derive long-term NEP averaged over the past sev
Authors
Susan E. Trumbore, Jill Bubier, Jennifer W. Harden, Patrick M. Crill
Gas and Isotope Geochemistry of 81 Steam Samples from Wells in The Geysers Geothermal Field, Sonoma and Lake Counties, California
The Geysers geothermal field in northern California,
with about 2000-MW electrical capacity, is the largest geothermal
field in the world. Despite its importance as a resource
and as an example of a vapor-dominated reservoir,
very few complete geochemical analyses of the steam have
been published (Allen and Day, 1927; Truesdell and others,
1987). This report presents data from 90 steam, gas,
Authors
Jacob B. Lowenstern, Cathy J. Janik, Lynne Fahlquist, Linda S. Johnson
Proceedings of the Workshop on Present and Future Directions in Volcano-Hazard Assessment; Menlo Park, California, September 23-24, 1998
No abstract available.
Authors
C. R. Bacon, T. C. Hanks, W. E. Scott
Volcano hazards in the Mount Jefferson region, Oregon
Mount Jefferson is a prominent feature of the landscape seen from highways east and west of the Cascades. Mount Jefferson (one of thirteen major volcanic centers in the Cascade Range) has erupted repeatedly for hundreds of thousands of years, with its last eruptive episode during the last major glaciation which culminated about 15,000 years ago. Geologic evidence shows that Mount Jefferson is capa
Authors
Joseph S. Walder, Cynthia A. Gardner, Richard M. Conrey, Bruce J. Fisher, Steven P. Schilling
Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii
The purpose of this paper is to present a complete account of contrasting yet related eruptions, thus filling a gap in the published narratives of recent activity of Kilauea; and to examine their significance within a broader context of regional magmatic and eruptive dynamics. We have gained a historical perspective and can view these three eruptions within a multidecade context of the eruptive be
Authors
John P. Lockwood, Robert I. Tilling, Robin T. Holcomb, Fred W. Klein, Arnold T. Okamura, Donald W. Peterson
Data on Holocene tephra (volcanic ash) deposits in the Alaska Peninsula and lower Cook Inlet region of the Aleutian volcanic arc, Alaska
This site provides information about the number, thickness, and grainsize of Holocene volcanic ash deposits at 50 localities in the eastern Aleutian volcanic arc. In addition, the major-element compositions of the glasses separated from more than 350 samples of tephra from these localities, determined by electron microprobe, are presented as a basis for correlating samples. Where known with reason
Authors
J.R. Riehle, C.E. Meyer, Ronny T. Miyaoka
Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins
Measurements of pore-fluid pressure and total bed-normal stress at the base of several ∼10 m3 experimental debris flows provide new insight into the process of debris-flow deposition. Pore-fluid pressures nearly sufficient to cause liquefaction were developed and maintained during flow mobilization and acceleration, persisted in debris-flow interiors during flow deceleration and deposition, and di
Authors
J. J. Major, R. M. Iverson
Gas-driven filter pressing in magmas
Most silicic and some mafic magmas expand via second boiling if they crystallize at depths of about 10 km or less. The buildup of gas pressure due to second boiling can be relieved by expulsion of melt out of the region of crystallization, and this process of gas-driven filter pressing assists the crystallization differentiation of magmas. For gas-driven filter pressing to be effective, the region
Authors
Thomas W. Sisson, Charles R. Bacon
Tsunami generation by pyroclastic flow during the 3500-year B.P. caldera-forming eruption of Aniakchak Volcano, Alaska
A discontinuous pumiceous sand, a few centimeters to tens of centimeters thick, is located up to 15 m above mean high tide within Holocene peat along the northern Bristol Bay coastline of Alaska. The bed consists of fine-to-coarse, poorly to moderately well-sorted, pumice-bearing sand near the top of a 2-m-thick peat sequence. The sand bed contains rip-up clasts of peat and tephra and is unique in
Authors
Christopher F. Waythomas, Christina A. Neal
Late Quaternary slip rate and seismic hazards of the West Klamath Lake fault zone near Crater Lake, Oregon Cascades
Crater Lake caldera is at the north end of the Klamath graben, where this N10°W-trending major Basin and Range structure impinges upon the north-south–trending High Cascades volcanic arc. East-facing normal faults, typically 10–15 km long, form the West Klamath Lake fault zone, which bounds the graben on its west side. The fault zone terminates on the south near the epicentral area of the Septembe
Authors
C. R. Bacon, M. A. Lanphere, D. E. Champion
Origin of the Columbia River basalts: Melting model of a heterogeneous plume head
In order to study the origin of the Grande Ronde basalts (GRs) erupted in the climax stage of the Columbia River basalts (CRBs), we carried out high pressure melting experiments on four of the most primitive rock compositions representing the Yakima group of the CRBs. The voluminous GRs (constituting >80 vol% of CRBs) are totally aphyric basaltic andesites. GRs show very narrow and coherent chemic
Authors
Eiichi Takahahshi, K Nakajima, Thomas L. Wright