Publications
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Retreat of northern margins of George VI and Wilkins Ice Shelves, Antarctic Peninsula Retreat of northern margins of George VI and Wilkins Ice Shelves, Antarctic Peninsula
The George VI and Wilkins Ice Shelves are considered at risk of disintegration due to a regional atmospheric warming trend on the Antarctic Peninsula. Retreat of the northern margin of the George VI Ice Shelf has been observed previously, but the Wilkins Ice Shelf was thought to be stable. We investigated the positions of the northern fronts of these shelves from the literature and...
Authors
Baerbel K. Lucchitta, Christina E. Rosanova
Large impact features on Europa: Results of the Galileo Nominal Mission Large impact features on Europa: Results of the Galileo Nominal Mission
The Galileo Orbiter examined several impact features on Europa at considerably better resolution than was possible from Voyager. The new data allow us to describe the morphology and infer the geology of the largest impact features on Europa, which are probes into the crust. We observe two basic types of large impact features: (1) “classic” impact craters that grossly resemble well...
Authors
Jeffrey M. Moore, Erik Asphaug, Robert J. Sullivan, James E. Klemaszewski, Kelly C. Bender, Ronald Greeley, Paul E. Geissler, Alfred S. McEwen, Elizabeth P. Turtle, Cynthia B. Phillips, B. Randy Tufts, James W. Head, Robert T. Pappalardo, Kevin B. Jones, Clark R. Chapman, Michael J.S. Belton, Randolph L. Kirk, David Morrison
Scaling laws from geomagnetic time series Scaling laws from geomagnetic time series
The notion of extended self-similarity (ESS) is applied here for the X-component time series of geomagnetic field fluctuations. Plotting nth order structure functions against the fourth order structure function we show that low-frequency geomagnetic fluctuations up to the order n = 10 follow the same scaling laws as MHD fluctuations in solar wind, however, for higher frequencies (f > 1/5...
Authors
Z. Voros, P. Kovacs, A. Juhasz, A. Kormendi, A.W. Green
The age and constitution of Cerro Campanario, a mafic stratovolcano in the Andes of central Chile The age and constitution of Cerro Campanario, a mafic stratovolcano in the Andes of central Chile
Cerro Campanario, a towering landmark on the continental divide near Paso Pehuenche, is a glacially eroded remnant of a mafic stratovolcano that is much younger than previously supposed. Consisting of fairly uniform basaltic andesite, rich in olivine and plagioclase, the 10-15 km3 edifice grew rapidly near the end of the middle Pleistocene, about 150-160 ka, as indicated by 40Ar/39Ar and...
Authors
Wes Hildreth, B. Singer, E. Godoy, F. Munizaga
Automated detection of Pi 2 pulsations using wavelet analysis: 1. Method and an application for substorm monitoring Automated detection of Pi 2 pulsations using wavelet analysis: 1. Method and an application for substorm monitoring
Wavelet analysis is suitable for investigating waves, such as Pi 2 pulsations, which are limited in both time and frequency. We have developed an algorithm to detect Pi 2 pulsations by wavelet analysis. We tested the algorithm and found that the results of Pi 2 detection are consistent with those obtained by visual inspection. The algorithm is applied in a project which aims at the...
Authors
M. Nose, T. Iyemori, M. Takeda, T. Kamei, D. K. Milling, D. Orr, H. J. Singer, E. W. Worthington, N. Sumitomo
Overview of the Mars Pathfinder Mission and assessment of landing site predictions Overview of the Mars Pathfinder Mission and assessment of landing site predictions
Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000...
Authors
M. P. Golombek, R. A. Cook, T. Economou, W. M. Folkner, A. F. C. Haldemann, P. H. Kallemeyn, J. M. Knudsen, R. M. Manning, H. J. Moore, T. J. Parker, R. Rieder, J. T. Schofield, P. H. Smith, R. M. Vaughan
Results from the Mars Pathfinder camera Results from the Mars Pathfinder camera
Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images...
Authors
P. H. Smith, J. F. Bell, N. T. Bridges, D.T. Britt, Lisa R. Gaddis, R. Greeley, H.U. Keller, Kenneth E. Herkenhoff, R. Jaumann, J. R. Johnson, Randolph L. Kirk, M. Lemmon, J.N. Maki, M.C. Malin, S.L. Murchie, J. Oberst, T. J. Parker, R.J. Reid, R.M. Sablotny, Laurence A. Soderblom, C. Stoker, R. Sullivan, N. Thomas, M.G. Tomasko, W. Ward, E. Wegryn
Post seismic deformation associated with the 1992 Mω = 7.3 Landers earthquake, southern California Post seismic deformation associated with the 1992 Mω = 7.3 Landers earthquake, southern California
Following the 1992 Mω=7.3 Landers earthquake, a linear array of 10 geodetic monuments at roughly 5‐km spacing was established across the Emerson fault segment of the Landers rupture. The array trends perpendicular to the local strike of the fault segment and extends about 30 km on either side of it. The array was surveyed by Global Positioning System 0.034, 0.048, 0.381, 1.27, 1.88, 2.60...
Authors
James C. Savage, Jerry L. Svarc
Surface strain accumulation and the seismic moment tensor Surface strain accumulation and the seismic moment tensor
Although the scalar moment accumulation rate within the seismogenic zone beneath a given area is sometimes deduced from the observed average surface strain accumulation rate over that same area (e.g., Working Group on California Earthquake Probabilities, 1995), the correspondence between the two is very uncertain. The equivalence between surface strain accumulation and scalar moment...
Authors
James C. Savage, Robert W. Simpson
Debris-flow hazards in the San Francisco Bay region Debris-flow hazards in the San Francisco Bay region
No abstract available.
Authors
Water Resources Division U.S. Geological Survey
The Loma Prieta, California, earthquake of October 17, 1989: Aftershocks and postseismic effects The Loma Prieta, California, earthquake of October 17, 1989: Aftershocks and postseismic effects
While the damaging effects of the earthquake represent a significant social setback and economic loss, the geophysical effects have produced a wealth of data that have provided important insights into the structure and mechanics of the San Andreas Fault system. Generally, the period after a large earthquake is vitally important to monitor. During this part of the seismic cycle, the...
Authors
Paul A. Reasenberg, Lynn D. Dietz, William L. Ellsworth, Robert W. Simpson, John W. Gephart, Susan Y. Schwartz, Glenn D. Nelson, H. Guo, A. Lerner-Lam, William Menke, Susan E. Hough, Leif Wennerberg, K.S. Breckenridge, Jeff Behr, Roger G. Bilham, Paul Bodin, Arthur G. Sylvester, Jon S. Galehouse, R. Burgmann, Paul Segall, Michael Lisowski, Jerry L. Svarc, John Langbein, Mark F. Linker, J.R. Rice, M. T. Gladwin, R. L. Gwyther, R.H.G. Hart, Randall Mackie, Theodore R. Madden, Edward A. Nichols