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Simulation of active tectonic processes for a convecting mantle with moving continents Simulation of active tectonic processes for a convecting mantle with moving continents

Numerical models are presented that simulate several active tectonic processes. These models include a continent that is thermally and mechanically coupled with viscous mantle flow. The assumption of rigid continents allows use of solid body equations to describe the continents' motion and to calculate their velocities. The starting point is a quasi-steady state model of mantle...
Authors
V. Trubitsyn, M. Kaban, Walter D. Mooney, C. Reigber, P. Schwintzer

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

Seismic characteristics of central Brazil crust and upper mantle: A deep seismic refraction study Seismic characteristics of central Brazil crust and upper mantle: A deep seismic refraction study

[1] A two‐dimensional model of the Brazilian central crust and upper mantle was obtained from the traveltime interpretation of deep seismic refraction data from the Porangatu and Cavalcante lines, each approximately 300 km long. When the lines were deployed, they overlapped by 50 km, forming an E‐W transect approximately 530 km long across the Tocantins Province and western São Francisco...
Authors
J.E. Soares, J. Berrocal, R.A. Fuck, Thomas Mooney, D.B.R. Ventura

Crustal structure of mainland China from deep seismic sounding data Crustal structure of mainland China from deep seismic sounding data

Since 1958, about ninety seismic refraction/wide angle reflection profiles, with a cumulative length of more than sixty thousand kilometers, have been completed in mainland China. We summarize the results in the form of (1) a new contour map of crustal thickness, (2) fourteen representative crustal seismic velocity–depth columns for various tectonic units, and, (3) a Pn velocity map. We...
Authors
S. Li, Walter D. Mooney, J. Fan

Blind comparisons of shear-wave velocities at closely-spaced sites in San Jose, California: Proceedings of a Workshop held at the US Geological Survey, Menlo Park, May 3, 2004 Blind comparisons of shear-wave velocities at closely-spaced sites in San Jose, California: Proceedings of a Workshop held at the US Geological Survey, Menlo Park, May 3, 2004

Shear-wave velocities within several hundred meters of Earth's surface are important in specifying earthquake ground motions for engineering design. Not only are the shearwave velocities used in classifying sites for use of modern building codes, but they are also used in site-specific studies of particularly significant structures. Many are the methods for estimating sub-surface shear...

Direct measurement of methane hydrate composition along the hydrate equilibrium boundary Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

The composition of methane hydrate, namely nw for CH4·nwH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nw may show a...
Authors
S. Circone, Stephen H. Kirby, Laura A. Stern

High-resolution seismic-reflection image of the Chesapeake Bay impact structure, NASA Langley Research Center, Hampton, Virginia High-resolution seismic-reflection image of the Chesapeake Bay impact structure, NASA Langley Research Center, Hampton, Virginia

A 1-kilometer-long (0.62-mile-long) seismic reflection and refraction profile collected at the National Aeronautics and Space Administration (NASA) Langley Research Center, Hampton, Va., provides a detailed image of part of the annular trough of the buried, 35-million-year-old Chesapeake Bay impact structure. This profile passes within 5 meters (m; 16.4 feet (ft)) of a 635.1-m-deep (2...
Authors
Rufus D. Catchings, David S. Powars, Gregory Gohn, Mark R. Goldman

Remotely triggered earthquakes following moderate mainshocks (or, why California is not falling into the ocean) Remotely triggered earthquakes following moderate mainshocks (or, why California is not falling into the ocean)

On several occasions in recent memory California has experienced apparent clusters of earthquake activity that are too far apart to be considered related according to a classic taxonomy that includes foreshocks, mainshocks, and aftershocks. During a week-long period in July 1986, California experienced the M 6.0 North Palm Springs earthquake, the M 5.5 Oceanside earthquake, and a swarm...
Authors
Susan E. Hough
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