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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

1998

Earth Sciences

Series

University of South Florida

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

Gps Measurement Of Surface Deformation Around Soufriere Hills Volcano, Montserrat From October 1995 To July 1996, Glen S. Mattioli, Timothy H. Dixon, Frederic Farina, Ellen S. Howell, Pamela E. Jansma, Alan L. Smith Sep 1998

Gps Measurement Of Surface Deformation Around Soufriere Hills Volcano, Montserrat From October 1995 To July 1996, Glen S. Mattioli, Timothy H. Dixon, Frederic Farina, Ellen S. Howell, Pamela E. Jansma, Alan L. Smith

School of Geosciences Faculty and Staff Publications

Global Positioning System geodesy was used to measure surface deformation on Soufriere Hills volcano, Montserrat from October 6, 1995 to July 1, 1997 during initial dome growth and gravitational collapse. Our data from this period show non-axially symmetric horizontal displacements, and decreasing subsidence as a function of radial distance from the former topographic high of the volcanic edifice. Forward modeling suggests that surface deformation is caused by a shallow vertical dike (< 3 km), which expanded approximately 1 m, coupled with a deflating Mogi source at about 6 km depth. These inferred source parameters are in good agreement with independent observations of regional dike widths and preemption magma storage depth.


Gps Measurements Athe Northern Caribbean Plate Boundary Zone: Impact Of Postseismic Relaxation Following Historic Earthquakes, Fred F. Pollitz, Timothy H. Dixon Jun 1998

Gps Measurements Athe Northern Caribbean Plate Boundary Zone: Impact Of Postseismic Relaxation Following Historic Earthquakes, Fred F. Pollitz, Timothy H. Dixon

School of Geosciences Faculty and Staff Publications

GPS measurements in the northern Caribbean suggest that the rate of Caribbean plate motion relative to North America is about 10 mm/yr faster than predicted by global plate motion model NUVEL-1A. Several of the key sites used in the GPS study are located in the Dominican Republic, near the rupture zones of large earthquakes in 1946 and in the previous two centuries. Postseismic relaxation of the crust and upper mantle is a possible explanation for the plate velocity discrepancy. We explore a range of fault mechanisms and crustal and mantle rheology to place an upper bound on postseismic relaxation effects. …


A Preliminary Assessment Of Wave, Current, And Sediment Interactions On The Louisiana Shoreface Adjacent To The Isles Dernieres, David A. Pepper, Gregory W. Stone, Ping Wang Jan 1998

A Preliminary Assessment Of Wave, Current, And Sediment Interactions On The Louisiana Shoreface Adjacent To The Isles Dernieres, David A. Pepper, Gregory W. Stone, Ping Wang

Geology Faculty Publications

The Louisiana coast is generally characterized as a low wave-energy environment where sediment transport is dominated by the influence of the Mississippi and the Atchafalaya Rivers. Winter cold fronts, however, generate waves and currents that have a significant impact on a variety of Louisiana’s coastal environments, although field data regarding their influence on the inner shelf are extremely sparse. During a 12-d period that included the passage of two cold fronts, waves and near-bed currents were measured on the Louisiana inner-shelf (depth-8 m) using a sophisticated bottom-mounted instrumentation system. Bottom boundary layer parameters were then calculated using wave-current interaction models, …