Publications
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Pre-1980 tephra-fall deposits erupted from Mount St. Helens, Washington Pre-1980 tephra-fall deposits erupted from Mount St. Helens, Washington
More than 100 tephra-fall deposits erupted from Mount St. Helens within about the last 40,000 years are grouped into tephra sets and layers distinguished from each other chiefly by differences in mineral composition and age. The tephra deposits record a complex history of the volcano, form important time-stratigraphic markers, and provide information about probable kinds, frequencies...
Authors
Donal R. Mullineaux
Long-period volcano seismicity: Its source and use in eruption forecasting Long-period volcano seismicity: Its source and use in eruption forecasting
At an active volcano, long-period seismicity (with typical periods in the range 0.2–2 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system, and hence provides a glimpse of the internal dynamics of the volcanic edifice. When this activity occurs at shallow depths, it may signal the pressure-induced disruption of the steam-dominated...
Authors
Bernard A. Chouet
Intermediate‐depth intraslab earthquakes and arc volcanism as physical expressions of crustal and uppermost mantle metamorphism in subducting slabs Intermediate‐depth intraslab earthquakes and arc volcanism as physical expressions of crustal and uppermost mantle metamorphism in subducting slabs
We elaborate on the well-known spatial association between axc volcanoes and Wadati Benioff zones and explore in detail their genetic relationships as dual physical expressions of slab metamorphism of the oceanic crust and uppermost mantle. At hypocentral depths less than 200 km intra slab Wadati-Benioff earthquakes tend to occur near the top surfaces of slabs. Subduction of very young...
Authors
Stephen H. Kirby, E. Robert Engdahl, Roger P. Denlinger
Knowledge of the fount and the cause of disaster Knowledge of the fount and the cause of disaster
No abstract available.
Authors
William C. Evans
Exsolved magmatic fluid and its role in the formation of comb-layered quartz at the Cretaceous Logtung W-Mo deposit, Yukon Territory, Canada Exsolved magmatic fluid and its role in the formation of comb-layered quartz at the Cretaceous Logtung W-Mo deposit, Yukon Territory, Canada
Comb-layered quartz is a type of unidirectional solidification texture found at the roofs of shallow silicic intrusions that are often associated spatially with Mo and W mineralisation. The texture consists of multiple layers of euhedral, prismatic quartz crystals (Type I) that have grown on subplanar aplite substrates. The layers are separated by porphyritic aplite containing equant...
Authors
Jacob B. Lowenstern, W. David Sinclair
Earthquakes and carbon dioxide beneath Mammoth Mountain, California Earthquakes and carbon dioxide beneath Mammoth Mountain, California
No abstract available.
Authors
David P. Hill
Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington Kulshan caldera: A quaternary subglacial caldera in the North Cascades, Washington
Calderas that collapse during large pyroclastic eruptions are anomalously rare in the Cascade arc. Recognition of the early Pleistocene 4.5 × 8 km Kulshan caldera, filled with rhyodacite ignimbrite at the northeast foot of Mount Baker, brings to only three the Quaternary calderas identified in the Cascades. A near-vertical ring fault cut in basement rocks of the North Cascades encloses...
Authors
W. Hildreth
This dynamic earth: the story of plate tectonics This dynamic earth: the story of plate tectonics
In the early 1960s, the emergence of the theory of plate tectonics started a revolution in the earth sciences. Since then, scientists have verified and refined this theory, and now have a much better understanding of how our planet has been shaped by plate-tectonic processes. We now know that, directly or indirectly, plate tectonics influences nearly all geologic processes, past and...
Authors
W. Jacquelyne Kious, Robert I. Tilling
Differentiation and magma mixing on Kilauea's east rift zone: A further look at the eruptions of 1955 and 1960. Part II. The 1960 lavas Differentiation and magma mixing on Kilauea's east rift zone: A further look at the eruptions of 1955 and 1960. Part II. The 1960 lavas
New and detailed petrographic observations, mineral compositional data, and whole-rock vs glass compositional trends document magma mixing in lavas erupted from Kilauea's lower east rift zone in 1960. Evidence includes the occurrence of heterogeneous phenocryst assemblages, including resorbed and reversely zoned minerals in the lavas inferred to be hybrids. Calculations suggest that this...
Authors
T. L. Wright, Rosalind Tuthill Helz
Observed discrepancy between geodolite and GPS distance measurements Observed discrepancy between geodolite and GPS distance measurements
Comparison of contemporaneous measurements of 84 distances in the range of 10 to 50 km by both Global Positioning System (GPS) and Geodolite (an electro-optical distance-measuring instrument) indicates that the Geodolite measurements are systematically longer by 0.283 ± 0.100 parts per million of the measured distance. Quoted uncertainty is 1 standard deviation. This amounts to 11.3 ± 4...
Authors
J.C. Savage, M. Lisowski, W.H. Prescott
Mauna Loa lava accumulation rates at the Hilo drill site: Formation of lava deltas during a period of declining overall volcanic growth Mauna Loa lava accumulation rates at the Hilo drill site: Formation of lava deltas during a period of declining overall volcanic growth
Accumulation rates for lava flows erupted from Mauna Loa, as sampled in the uppermost 280 m of the Hilo drill hole, vary widely for short time intervals (several thousand years), but overall are broadly similar to those documented elsewhere on this volcano since 100 ka. Thickness variations and accumulation rates for Mauna Loa lavas at the Hilo drill site have been strongly affected by...
Authors
P. W. Lipman, J.G. Moore