Geology topics

Timothy Dixon

Publications and source records attributed to Timothy Dixon.

4 recordsLinked to original sources

USGS2022

Assessing global geologic carbon dioxide storage resources

The U.S. Geological Survey (USGS), in conjunction with the U.S. Department of Energy (U.S. DOE) Office of Fossil Energy and Carbon Management (FECM), the IEA Greenhouse Gas R&D Programme (IEAGHG), and the Clean Energy Ministerial Carbon Capture, Utilization and Storage Initiative (CEM-CCUS Initiative), plans to work with partner nations to assess geologic carbon dioxide (CO2) storage resources globally. The goal of this work is to help countries, particularly those with emerging economies, understand the mass of CO2 they could potentially store in geologic units within their borders. Knowledge of the CO2 storage resources in their geologic units can provide countries pathways for reducing emissions to meet their future climate mitigation goals.

Conference Paper↗

USGS2012

Inflation of Long Valley Caldera from one year of continuous GPS observations

A permanent Global Positioning System receiver at Casa Diablo Hot Springs, Long Valley Caldera, California was installed in January, 1993, and has operated almost continuously since then. The data have been transmitted daily to the Jet Propulsion Laboratory for routine analysis with data from the Fiducial Laboratories for an International Natural sciences Network (FLINN) by the JPL FLINN analysis center. Results from these analyses have been used to interpret the on going deformation at Long Valley, with data excluded from periods when the antenna was covered under 2.5 meters of snow and from some periods when Anti Spoofing was enforced on the GPS signal. The remaining time series suggests that uplift of the resurgent dome of Long Valley Caldera during 1993 has been 2.5±1.1 cm/yr and horizontal motion has been 3.0±0.7 cm/yr at S53W in a no-net-rotation global reference frame, or 1.5±0.7 cm/yr at S14W relative to the Sierra Nevada block. These rates are consistent with uplift predicted from frequent horizontal strain measurements. Spectral analysis of the observations suggests that tidal forcing of the magma chamber is not a source of the variability in the 3 dimensional station location. These results suggest that remotely operated, continuously recording GPS receivers could prove to be a reliable tool for volcano monitoring throughout the world.

California↗

USGS2006

The global topography mission gains momentum

An accurate description of the surface elevation of the Earth is of fundamental importance to many branches of Earth science. Continental topographic data are required for studies of hydrology, ecology, glaciology, geomorphology, and atmospheric circulation. For example, in hydrologic and terrestrial ecosystem studies, topography exerts significant control on intercepted solar radiation, water runoff and subsurface water inventory, microclimate, vegetation type and distribution, and soil development. The topography of the polar ice caps and mountain glaciers directly reflects ice-flow dynamics and is closely linked to global climate and sea level change.

Eos, Transactions, American Geophysical Union↗

USGS2004

Geodetic and seismic constraints on some seismogenic zone processes in Costa Rica

New seismic and geodetic data from Costa Rica provide insight into seismogenic zone processes in Central America, where the Cocos and Caribbean plates converge. Seismic data are from combined land and ocean bottom deployments in the Nicoya peninsula in northern Costa Rica and near the Osa peninsula in southern Costa Rica. In Nicoya, inversion of GPS data suggests two locked patches centered at 14 ± 2 and 39 ± 6 km depth. Interplate microseismicity is concentrated in the more freely slipping intermediate zone, suggesting that small interseismic earthquakes may not accurately outline the updip limit of the seismogenic zone, the rupture zone for future large earthquakes, at least over the short (∼1 year) observation period. We also estimate northwest motion of a coastal “sliver block” at 8 ± 3 mm/yr, probably related to oblique convergence. In the Osa region to the south, convergence is orthogonal to the trench. Cocos-Caribbean relative motion is partitioned here, with ∼8 cm/yr on the Cocos-Panama block boundary (including a component of permanent shortening across the Fila Costeña fold and thrust belt) and ∼1 cm/yr on the Panama block–Caribbean boundary. The GPS data suggest that the Cocos plate–Panama block boundary is completely locked from ∼10–50 km depth. This large locked zone, as well as associated forearc and back-arc deformation, may be related to subduction of the shallow Cocos Ridge and/or younger lithosphere compared to Nicoya, with consequent higher coupling and compressive stress in the direction of plate convergence.

Nicoya Peninsula, Osa Peninsula↗