Publications
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Rhyodacites of Kulshan caldera, North Cascades of Washington: Postcaldera lavas that span the Jaramillo Rhyodacites of Kulshan caldera, North Cascades of Washington: Postcaldera lavas that span the Jaramillo
Kulshan caldera (4.5×8 km), at the northeast foot of Mount Baker, is filled with rhyodacite ignimbrite (1.15 Ma) and postcaldera lavas and is only the third Quaternary caldera identified in the Cascade arc. A gravity traverse across the caldera yields a steep-sided, symmetrical, complete Bouguer anomaly of −16 mGal centered over the caldera. Density considerations suggest that the...
Authors
W. Hildreth, M. A. Lanphere, D.E. Champion, J. Fierstein
Dispersal scaling from the world's rivers Dispersal scaling from the world's rivers
Although rivers provide important biogeochemical inputs to oceans, there are currently no descriptive or predictive relationships of the spatial scales of these river influences. Our combined satellite, laboratory, field and modeling results show that the coastal dispersal areas of small, mountainous rivers exhibit remarkable self-similar scaling relationships over many orders of...
Authors
J.A. Warrick, D.A. Fong
Shear wave velocity, seismic attenuation, and thermal structure of the continental upper mantle Shear wave velocity, seismic attenuation, and thermal structure of the continental upper mantle
Seismic velocity and attenuation anomalies in the mantle are commonly interpreted in terms of temperature variations on the basis of laboratory studies of elastic and anelastic properties of rocks. In order to evaluate the relative contributions of thermal and non-thermal effects on anomalies of attenuation of seismic shear waves, Q−1s, and seismic velocity, Vs, we compare global maps of...
Authors
I.M. Artemieva, M. Billien, J.-J. Leveque, Walter D. Mooney
The coefficient of friction of chrysotile gouge at seismogenic depths The coefficient of friction of chrysotile gouge at seismogenic depths
We report new strength data for the serpentine mineral chrysotile at effective normal stresses, σn between 40 and 200 MPa in the temperature range 25°-280°C. Overall, the coefficient of friction, μ (= shear stress/effective normal stress) of water-saturated chrysotile gouge increases both with increasing temperature and σn, but the rates vary and the temperature-related increases begin...
Authors
Diane E. Moore, D.A. Lockner, H. Tanaka, K. Iwata
The Spirit Rover's Athena science investigation at Gusev crater, Mars The Spirit Rover's Athena science investigation at Gusev crater, Mars
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former take, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks...
Authors
S. W. Squyres, R. E. Arvidson, J.F. Bell, J. Bruckner, N.A. Cabrol, W. Calvin, M. H. Carr, P. R. Christensen, B. C. Clark, L. Crumpler, D.J. Des Marais, C. D'Uston, T. Economou, J. Farmer, W. Farrand, W. Folkner, M. Golombek, S. Gorevan, J. A. Grant, R. Greeley, J. Grotzinger, L. Haskin, Kenneth E. Herkenhoff, S. Hviid, J. Johnson, G. Klingelhofer, A. Knoll, G. Landis, M. Lemmon, R. Li, M.B. Madsen, M. C. Malin, S. M. McLennan, H.Y. McSween, D. W. Ming, J. Moersch, R.V. Morris, T. Parker, J. W. Rice, L. Richter, R. Rieder, M. Sims, M. Smith, P. Smith, Laurence A. Soderblom, R. Sullivan, H. Wanke, T. Wdowiak, M. Wolff, A. Yen
Crustal structure along the geosciences transect from Altay to Altun Tagh Crustal structure along the geosciences transect from Altay to Altun Tagh
No abstract available.
Authors
Y.-X. Wang, G.-H. Han, M. Jiang, X.-C. Yuan, Walter D. Mooney, R. G. Coleman
Late Quaternary evolution of channel and lobe complexes of Monterey Fan Late Quaternary evolution of channel and lobe complexes of Monterey Fan
The modern Monterey submarine fan, one of the largest deep-water deposits off the western US, is composed of two major turbidite systems: the Neogene Lower Turbidite System (LTS) and the late Quarternary Upper Turbidite System (UTS). The areally extensive LTS is a distal deposit with low-relief, poorly defined channels, overbank, and lower-fan elements. The younger UTS comprises almost...
Authors
Andrea Fildani, William R. Normark
Strain accumulation across the Coast Ranges at the latitude of San Francisco, 1994-2000 Strain accumulation across the Coast Ranges at the latitude of San Francisco, 1994-2000
A 66-monument geodetic array spanning the Coast Ranges near San Francisco has been surveyed more than eight times by GIPS between late 1993 and early 2001. The measured horizontal velocities of the monuments are well represented by uniform, right-lateral, simple shear parallel to N29°W. (The local strike of the San Andreas Fault is ∼N34°W.) The observed areal dilatation rate of 6.9 ± 10...
Authors
J.C. Savage, Weijun Gan, W.H. Prescott, J. L. Svarc
Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA Magmatic precursors to the 18 May 1980 eruption of Mount St. Helens, USA
Perhaps the most difficult task facing volcanologists today is that of distinguishing between low-level volcanic restlessness and activity that presages a full-scale eruption. We illustrate these difficulties by reexamining the sequence of events that led to the 18 May 1980 eruption of Mount St. Helens, activity that is often presented as a classic example of early phreatic explosions...
Authors
K. V. Cashman, R. Hoblitt
Coastal vulnerability assessment of Assateague Island National Seashore (ASIS) to sea-level rise Coastal vulnerability assessment of Assateague Island National Seashore (ASIS) to sea-level rise
A coastal vulnerability index (CVI, http://pubs.usgs.gov/of/2004/1020/html/cvi.htm) was used to map relative vulnerability of the coast to future sea-level rise within Assateague Island National Seashore (ASIS) in Maryland and Virginia. The CVI ranks the following in terms of their physical contribution to sea-level rise-related coastal change: geomorphology, regional coastal slope, rate...
Authors
Elizabeth A. Pendleton, S. Jeffress Williams, E. Robert Thieler
Landslides triggered by the 2002 Denali fault, Alaska, earthquake and the inferred nature of the strong shaking Landslides triggered by the 2002 Denali fault, Alaska, earthquake and the inferred nature of the strong shaking
The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15 ?? 106 m3. The pattern of landsliding was unusual; the number of slides was less than expected for an earthquake of this magnitude, and the landslides were...
Authors
R.W. Jibson, E. L. Harp, W. Schulz, D. K. Keefer
Eruptive history and chemical evolution of the precaldera and postcaldera basalt-dacite sequences, Long Valley, California: Implications for magma sources, current seismic unrest, and future volcanism Eruptive history and chemical evolution of the precaldera and postcaldera basalt-dacite sequences, Long Valley, California: Implications for magma sources, current seismic unrest, and future volcanism
The Long Valley Volcanic Field in east-central California straddles the East Sierran frontal fault zone, overlapping the Sierra Nevada and western Basin and Range Provinces. The volcanic field overlies a mature mid-Tertiary erosional surface that truncates a basement composed mainly of Mesozoic plutons and associated roof pendants of Mesozoic metavolcanic and Paleozoic metasedimentary...
Authors
Roy A. Bailey