Publications
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Nature and mechanics of the mount St Helens rockslide — avalanche of 18 May 1980 Nature and mechanics of the mount St Helens rockslide — avalanche of 18 May 1980
The bulging sector of the north slope of Mount St. Helens collapsed on 18 May 1980, triggered by an earthquake, thereby creating a tremendous mass movement. This movement in turn initiated volcanic eruptions resulting in the formation of an avalanche of debris. Limit equilibrium analysis of the slope suggests that failure was due to several culminating factors, including progressive...
Authors
Barry Voight, R. J. Janda, H. Glicken
Sea-floor-mounted rotating side-scan sonar for making time-lapse sonographs Sea-floor-mounted rotating side-scan sonar for making time-lapse sonographs
A rotating side-scan sonar system was designed to make time-lapse sonographs of a circular area of the sea floor. To construct the system, the transducers of a commercial side-scan system (frequency 105 kHz; pulse length 0.1 ms; horizontal beam width 1°; vertical beam width 20°; beam depressed 10° with respect to horizontal) were mounted 2 m above the sea floor on a vertical shaft that...
Authors
David M. Rubin, David S. McCulloch, Harry R. Hill
Landslide risk assessment Landslide risk assessment
Landslide risk can be assessed by evaluating geological conditions associated with past events. A sample of 2,4 16 slides from urban areas in West Virginia, each with 12 associated geological factors, has been analyzed using SAS computer methods. In addition, selected data have been normalized to account for areal distribution of rock formations, soil series, and slope percents. Final...
Authors
P. Lessing, C.P. Messina, R.F. Fonner
Sensitivity of selected geomagnetic properties to truncation level of spherical harmonic expansions Sensitivity of selected geomagnetic properties to truncation level of spherical harmonic expansions
A two day selection of MAGSAT data is fit by spherical harmonic series truncated at increasing levels NF in the range 2
Authors
E.R. Benton, Ronald H. Estes, R.A. Langel, L.A. Muth
Crustal structure beneath the southern Appalachians: Nonuniqueness of gravity modeling Crustal structure beneath the southern Appalachians: Nonuniqueness of gravity modeling
Gravity models computed for a profile across the long-wavelength paired negative-positive Bouguer anomalies of the southern Appalachian Mountains show that the large negative anomaly can be explained by a crustal root zone, whereas the steep gradient and positive anomaly east of the root may be explained equally well by three different geometries: a suture zone, a mantle upwarp, or a...
Authors
Deborah R. Hutchinson, John A. Grow, Kim D. Klitgord
Triggering of large earthquakes by magma-chamber inflation, Izu Peninsula (Japan) Triggering of large earthquakes by magma-chamber inflation, Izu Peninsula (Japan)
A close spatial and temporal association between three aseismic uplift episodes and subsequent large (M ≈ 7) earthquakes on the Izu Peninsula, Japan, suggests a causal relation. Quaternary geology, as well as studies by other workers, indicates a volcanic origin for the observed uplift, and we use a simple inflation model constrained by leveling data to compute the expected increments in...
Authors
Wayne R. Thatcher, James C. Savage
Ice sculpture in the Martian outflow channels Ice sculpture in the Martian outflow channels
Many landforms in Martian outflow channels have characteristics that suggest sculpture by glaciers, ice streams, or ice sheets. Viking Orbiter and terrestrial satellite images were examined at similar resolution to compare features of the Martian outflow channels to features produced by the movement of ice on earth. Many resemblances were found. They include the anastomoses, sinuosities...
Authors
Baerbel K. Lucchitta
Reflection—refraction of general P- and type-I S-waves in elastic and anelastic solids Reflection—refraction of general P- and type-I S-waves in elastic and anelastic solids
The reflection and refraction of general (homogeneous or inhomogeneous) plane P and type-I S(SV) body waves incident on plane boundaries are considered for general linear viscoelastic solids. Reflection—refraction laws, physical characteristics of the waves, and the nature of critical angles are examined in detail at welded boundaries and a free surface. General visco-elasticity with no...
Authors
Roger D. Borcherdt
On the status of in-situ strong ground motion and structural response investigations On the status of in-situ strong ground motion and structural response investigations
No abstract available.
Authors
C. Rojahn, Roger D. Borcherdt
Seismic zonation of the Los Angeles region: A progress report Seismic zonation of the Los Angeles region: A progress report
No abstract available.
Authors
S. T. Algermissen, B. L. Askew, Roger D. Borcherdt, R. H. Campbell, S. H. Clarke, Jack F. Evernden, T. E. Fumal, J. F. Gibbs, H. G. Greene, Thomas C. Hanks, E. L. Harp, S.H. Hartzell, M. G. Hooper, C.E. Johnson, W. B. Joyner, D. K. Keefer, W. J. Kockelman, D. S. McCulloch, D. M. Perkins, A. M. Rogers, P. A. Spudich, P.C. Thenhaus, J. C. Tinsley, R. C. Wilson, R.F. Yerkes, T. L. Youd, J. I. Ziony
Application of wave field continuation to the inversion of refraction data Application of wave field continuation to the inversion of refraction data
Three examples of the inversion of refraction data by downward continuation illustrate the applicability of the method to field data. The first example is a refraction profile from the Mojave Desert, California. These data are spatially aliased and contain clear evidence of lateral inhomogeneity. The inversion in this case produces a broken image in the slowness‐depth domain due to the...
Authors
G. A. McMechan, Robert W. Clayton, Walter D. Mooney