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The derivation of World Magnetic Model 2000 The derivation of World Magnetic Model 2000

This report contains a detailed summary of the data used, the modelling techniques employed and the results obtained in the production of the World Magnetic Model 2000. This model is designed for use in air and sea navigation systems and is valid till 2005.0. The derivation of World Magnetic Model 2000 has been the joint responsibility of the British Geological Survey (BGS) and the...
Authors
Susan Macmillan, John M. Quinn

Methane hydrate dissociation rates at 0.1 MPa and temperatures above 272 K Methane hydrate dissociation rates at 0.1 MPa and temperatures above 272 K

We performed rapid depressurization experiments on methane hydrate under isothermal conditions above 272 K to determine the amount and rate of methane evolution. Sample temperatures rapidly drop below 273 K and stabilize near 272.5 K during dissociation. This thermal anomaly and the persistence of methane hydrate are consistent with the reported recovery of partially dissociated methane...
Authors
S. Circone, Laura A. Stern, Stephen H. Kirby, John C. Pinkston, William B Durham

Duration of sedimentation of Creede Formation from 40Ar/39Ar ages Duration of sedimentation of Creede Formation from 40Ar/39Ar ages

The Oligocene Creede Formation was deposited in the moat of the Creede caldera, which formed as a result of eruption of ythe Snowshoe Mountains Tuff. The Creede Formation in the two moat drill holes contains ash layers that are considered fallout tuffs derived from Fisher Dacite volcanoes that were erupting during accumulation of the Creede Formation. The duration of sedimentation of the...
Authors
Marvin A. Lanphere

Landslides and tsunamis Landslides and tsunamis

The study of tsunamis has been shifting away from theoretical modeling of tsunami source, wave propagation and runup toward multidisciplinary investigations, with an emphasis on field studies. This collection of papers highlights the many approaches being utilized to study landslides and tsunamis.
Authors
Christopher F. Waythomas, Alastair G. Dawson

Volcanism and ice interactions on Earth and Mars Volcanism and ice interactions on Earth and Mars

Volcano/ice interactions produce meltwater. Meltwater can enter the groundwater cycle and under the influence of hydrothermal systems, it can be later discharged to form channels and valleys or cycled upward to melt permafrost. Water or ice-saturated ground can erupt into phreatic craters when covered by lava. Violent mixing of meltwater and volcanic material and rapid release can...
Authors
Mary G. Chapman, Carlton C. Allen, Magnus T. Gudmundsson, Virginia C. Gulick, Sveinn P. Jakobsson, Baerbel K. Lucchitta, Ian P. Skilling, Richard B. Waitt

SMSIM--Fortran programs for simulating ground motions from earthquakes: Version 2.0.--a revision of OFR 96-80-A SMSIM--Fortran programs for simulating ground motions from earthquakes: Version 2.0.--a revision of OFR 96-80-A

A simple and powerful method for simulating ground motions is based on the assumption that the amplitude of ground motion at a site can be specified in a deterministic way, with a random phase spectrum modified such that the motion is distributed over a duration related to the earthquake magnitude and to distance from the source. This method of simulating ground motions often goes by the...
Authors
David M. Boore

Preliminary method for anticipating the occurrence of precipitation-induced landslides in Seattle, Washington Preliminary method for anticipating the occurrence of precipitation-induced landslides in Seattle, Washington

Analysis of precipitation data associated with historical landslide events in Seattle has resulted in the identification of precipitation thresholds for the initiation of landslides. Also, an air-temperature index for multiple landslide events is identified, and in conjunction with the precipitation thresholds, is used to develop a method for anticipating the occurrence of landslides...
Authors
Alan F. Chleborad

Surface ages and resurfacing rates of the Polar Layered Deposits on Mars Surface ages and resurfacing rates of the Polar Layered Deposits on Mars

Interpretation of the polar stratigraphy of Mars in terms of global climate changes is complicated by the significant difference in surface ages between the north and south polar layered terrains inferred from crater statistics. We have reassessed the cratering record in both polar regions using Viking Orbiter and Mariner 9 images. No craters have been found in the north polar layered...
Authors
Kenneth E. Herkenhoff, Jeffrey J. Plaut

Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600°C and 1000°C: II. Mechanical properties Hydrogen defects in α-Al2O3 and water weakening of sapphire and alumina ceramics between 600°C and 1000°C: II. Mechanical properties

Hydrogen impurities in alumina have been introduced by hydrothermal annealing (see part I). In this paper, we report on reductions in the flow strength of α-Al2O3 single crystals and polycrystals associated with hydrogen incorporation. Prior to deformation, α-Al2O3 single crystal and ceramic specimens were annealed in the presence of supercritical water at 850° or 900°C, under 1500 MPa...
Authors
J. Castaing, A. K. Kronenberg, S. H. Kirby, T. E. Mitchell
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