Publications
Filter Total Items: 7620
Identifying the effects of petrologic processes in a closed basaltic system using trace element concentrations in olivines and glasses: Implications for comparative planetology Identifying the effects of petrologic processes in a closed basaltic system using trace element concentrations in olivines and glasses: Implications for comparative planetology
We use trace-element concentrations in olivines and glasses from a closed basaltic system to identify the effects of petrologic processes on the trace-element record of that system. The closed basaltic system in question is the Makaopuhi Lava Lake (MLL), which is closed with respect to magma mixing. Detailed studies of this lava lake have provided important information about system...
Authors
Justin Hagerty, Charles K. Shearer, David Vaniman, Paul V. Burger
The San Andreas fault in Sonoma and Mendocino counties The San Andreas fault in Sonoma and Mendocino counties
This two-day trip explores the northern San Andreas fault in the Gualala area between Fort Ross and Point Arena (Fig. 1). The first stop overlooks the Golden Gate Bridge and includes a discussion of its in-progress seismic retrofit. Several subsequent stops are at paleoseismic sites on the San Andreas fault. The stop at Annapolis Road includes a short hike along the fault through the...
Authors
Carol S. Prentice, Keith I. Kelson
Source scaling telationships of microearthquakes at Parkfield, CA, determined using the SAFOD pilot hole seismic array Source scaling telationships of microearthquakes at Parkfield, CA, determined using the SAFOD pilot hole seismic array
Weestimate thesourceparametersof34microearthquakes at Parkfield,CA,ranginginsizefromM-0.2 toM2.1, byanalyzingseismogramsrecorded bythe32-level, 3-componentseismic arrayinstalled in theSAFODPilotHole. Wesucceeded in obtainingstablespectral ratios by stacking theratioscalculatedfromthemovingwindowstakenalongtherecordfollowingthedirectwaves.Thesespectral ratios were modeledtodetermine...
Authors
Kazutoshi Imanishi, William L. Ellsworth
Earthquake Trail, Sanborn County Park: A geology hike along the San Andreas fault Earthquake Trail, Sanborn County Park: A geology hike along the San Andreas fault
On the southern part of the San Francisco Peninsula, the San Andreas fault traverses the actively uplifting Santa Cruz Mountains. The field guide is comprised of a hiking tour along the fault in Sanborn County fault, a visit to a winery and vineyards traversed by the fault, and visits to two wineries that provide vistas of the San Andreas Rift Valley and surroundings.
Authors
Philip W. Stoffer
Shocked plagioclase signatures in Thermal Emission Spectrometer data of Mars Shocked plagioclase signatures in Thermal Emission Spectrometer data of Mars
The extensive impact cratering record on Mars combined with evidence from SNC meteorites suggests that a significant fraction of the surface is composed of materials subjected to variable shock pressures. Pressure-induced structural changes in minerals during high-pressure shock events alter their thermal infrared spectral emission features, particularly for feldspars, in a predictable...
Authors
Jeffrey R. Johnson, Matthew I. Staid, Timothy N. Titus, Kris J. Becker
Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA Geodetic observations and modeling of magmatic inflation at the Three Sisters volcanic center, central Oregon Cascade Range, USA
Tumescence at the Three Sisters volcanic center began sometime between summer 1996 and summer 1998 and was discovered in April 2001 using interferometric synthetic aperture radar (InSAR). Swelling is centered about 5 km west of the summit of South Sister, a composite basaltic-andesite to rhyolite volcano that last erupted between 2200 and 2000 yr ago, and it affects an area ∼20 km in...
Authors
Daniel Dzurisin, Michael Lisowski, Charles W. Wicks, Michael P. Poland, Elliot T. Endo
Real-time measurement of volcanic SO2 emissions: Validation of a new UV correlation spectrometer (FLYSPEC) Real-time measurement of volcanic SO2 emissions: Validation of a new UV correlation spectrometer (FLYSPEC)
A miniaturized, lightweight and low-cost UV correlation spectrometer, the FLYSPEC, has been developed as an alternative for the COSPEC, which has long been the mainstay for monitoring volcanic sulfur dioxide fluxes. Field experiments have been conducted with the FLYSPEC at diverse volcanic systems, including Masaya (Nicaragua), Poás (Costa Rica), Stromboli, Etna and Vulcano (Italy)...
Authors
Keith A. Horton, Glyn Williams-Jones, Harold Garbeil, Tamar Elias, A. Jeff Sutton, Peter J. Mouginis-Mark, John T. Porter, Steven Clegg
Crustal structure across the Altyn Tagh Range at the northern margin of the Tibetan Plateau and tectonic implications Crustal structure across the Altyn Tagh Range at the northern margin of the Tibetan Plateau and tectonic implications
We present new seismic refraction/wide-angle-reflection data across the Altyn Tagh Range and its adjacent basins. We find that the crustal velocity structure, and by inference, the composition of the crust changes abruptly beneath the Cherchen fault, i.e., ∼100 km north of the northern margin of the Tibetan plateau. North of the Cherchen fault, beneath the Tarim basin, a platform-type...
Authors
J. Zhao, Walter D. Mooney, X. Zhang, Z. Li, Z. Jin, N. Okaya
Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars
Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have...
Authors
H.Y. McSween, M.B. Wyatt, Ralf Gellert, J.F. Bell, R.V. Morris, Kenneth E. Herkenhoff, L.S. Crumpler, K.A. Milam, K.R. Stockstill, L.L. Tornabene, R. E. Arvidson, P. Bartlett, D. Blaney, N.A. Cabrol, P. R. Christensen, B. C. Clark, J.A. Crisp, D.J. Des Marais, T. Economou, J.D. Farmer, W. Farrand, A. Ghosh, M. Golombek, S. Gorevan, R. Greeley, V.E. Hamilton, J. R. Johnson, B.L. Joliff, G. Klingelhofer, A.T. Knudson, S. McLennan, D. Ming, J.E. Moersch, R. Rieder, S. W. Ruff, C. Schroder, P.A. de Souza, S. W. Squyres, H. Wanke, A. Wang, A. Yen, J. Zipfel
Constraints on the mechanism of long-term, steady subsidence at Medicine Lake volcano, northern California, from GPS, leveling, and InSAR Constraints on the mechanism of long-term, steady subsidence at Medicine Lake volcano, northern California, from GPS, leveling, and InSAR
Leveling surveys across Medicine Lake volcano (MLV) have documented subsidence that is centered on the summit caldera and decays symmetrically on the flanks of the edifice. Possible mechanisms for this deformation include fluid withdrawal from a subsurface reservoir, cooling/crystallization of subsurface magma, loading by the volcano and dense intrusions, and crustal thinning due to...
Authors
Michael P. Poland, Roland Burgmann, Daniel Dzurisin, Michael Lisowski, Timothy Masterlark, Susan Owen, Jonathan Fink
Sulfate deposition in subsurface regolith in Gusev crater, Mars Sulfate deposition in subsurface regolith in Gusev crater, Mars
Excavating into the shallow Martian subsurface has the potential to expose stratigraphic layers and mature regolith, which may hold a record of more ancient aqueous interactions than those expected under current Martian surface conditions. During the Spirit rover's exploration of Gusev crater, rover wheels were used to dig three trenches into the subsurface regolith down to 6-11 cm depth...
Authors
A. Wang, L.A. Haskin, S. W. Squyres, B.L. Jolliff, L. Crumpler, Ralf Gellert, C. Schroder, Kenneth E. Herkenhoff, J. Hurowitz, N.J. Tosca, W. H. Farrand, R. Anderson, A.T. Knudson