Assembly of a crustal seismic velocity database for the western Great Basin
Project Description
This is a sub-project of the "Expanding Geothermal Resource Utilization in Nevada through Directed Research and Public Outreach" project of the Great Basin Center for Geothermal Energy at UNR. Its purpose is to assemble a three-dimensional reference model of crustal seismic velocity for the western Great Basin region of Nevada and eastern California. The seismic velocity model consists of simplified rule-based representations of region's crust to 50 km depth, and more detailed characterization of geothermal areas and sedimentary basins. We are compiling velocity information from sources in the literature, results of previous seismic experiments and earthquake-monitoring projects, and data donated from mining, geothermal, and petroleum companies. We also collected (May 2002 and August 2004) two new crustal refraction profiles across western Nevada and the northern and central Sierra.
|
Principal
Investigator(s) |
|
John N. Louie, Associate Professor of Seismology, Geological Sciences,
Mackay School of Earth Sciences and Engineering. louie@seismo.unr.edu
|
|
| Participants | Students Weston Thelen, James B. Scott, Matthew Clark, Shane B. Smith; Industry collaborator Satish Pullammanappallil, Optim LLC |
| Impact | With the resulting more complete sampling of the crustal geophysical characteristics of geothermal resources in the Great Basin, these measures have contributed to quantitative analyses of the associations between different indicators. Under the Center's goal "(1) Geothermal Resource Assessment and Exploration: B. Identification and Characterization of New Potential Geothermal Resource Targets," this project contributes critical data toward the effective exploration for new geothermal resources. |
| Project Duration | May 2002 - Sept. 2006 |
| Web Site | http://www.seismo.unr.edu/geothermal |
| Outreach Audience | Geothermal industry and applicable regulators. |
| Project Focus |
|
Earth Science
|
|
People, Social Sciences, Education, Outreach
|
|
Updated: 3/3/2005
|
|
Influence Of Fuel Reduction Alternatives On Forest Soil Properties And The Carbon Cycle
Project Description
Woody shrubs invading forest lands following fire create major problems in urban/wildland interfaces of the West. Aggressive woody shrubs not only weaken forest trees and delay the return of forest cover, they also lead to a continuous fuel buildup between the ground and tree canopy, thus creating a high risk of catastrophic losses from recurrent fire. The traditional means of dealing with fuel buildup -prescribed fire - is impractical in a mosaic of wildlands and residential holdings. Furthermore, prescribed fire leads to gaseous losses of carbon and nitrogen which may lower soil quality. Alternative means must be found that reduce fuel loads of woody shrubs, retain organic carbon and nitrogen on the site, and enhance soil properties associated with soil stability, water supply, and nutrient availability.
|
Principal
Investigator(s) |
|
Dale Johnson, Professor of Forest Soil Chemistry, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. dwj@cabnr.unr.edu
|
|
| Participants | Robert F. Powers, USFS |
| Project Focus |
|
Earth Science
|
|
Terrestrial Life
|
|
Fire
|
|
Updated: 12/20/2004
|
|
Monitoring Tectonic Extension and Lake Loading of the Tahoe Basin with GPS
Project Description
The Tahoe basin is a region of active tectonics, that exhibits crustal faulting and seismicity. The basin was formed, in part, by crustal blocks that are slowly pulling apart, generating small to moderate earthquakes that are frequently recorded by UNR’s regional seismic network. Recently, a swarm of seismicity deep in the crust was associated with a surface bulge that was detected with high precision measurements with the Global Positioning System (GPS) (Smith et al., 2004). The seismicity and deformation are consistent with the motion of fluids, most likely magma, in the deep crust. The existence of deep magma is supported by the presence of geologically recent lava flows (~1-2 million years old).
In order to monitor and characterize these ongoing deep processes, and to measure the contemporary tectonic extension of the Tahoe basin we have deployed high precision GPS receivers in the vicinity of North Lake Tahoe to complement the seismic monitoring of the region. In addition, the resources of the EarthScope Plate Boundary Observatory have been mobilized to add four more continuously recording GPS receivers by spring 2006. These high precision GPS receivers can measure movements on the surface as small as a few millimeters, and we use them to infer the existence or pattern of deformations that occur deep (as far as 10s of kilometers) below the surface. The combined GPS and seismic measurements will allow us to evaluate different physical models for how these fluids move, and their role in the steady tectonic extension of the western Great Basin.
Additionally, this new GPS network together with other continuously recording stations in the area may be able to detect loading of the crust associated with seasonal changes in the mass of the Lake water and regional snow load. Combined with lake level and snow level data, these measurements can provide constraints on the structure and dynamics of the lithosphere, and time-dependent stress changes that can possibly influence crustal faults.
|
Principal
Investigator(s) |
|
Geoffrey Blewitt, Research Professor of Space Geodesy, Nevada Bureau of Mines and Geology,
Mackay School of Earth Sciences and Engineering. gblewitt@unr.edu
|
|
William C Hammond, Assistant Research Professor, Nevada Bureau of Mines and Geology,
Mackay School of Earth Sciences and Engineering. whammond@unr.edu
|
|
Corne Kreemer, Assistant Research Professor, Nevada Bureau of Mines and Geology,
Mackay School of Earth Sciences and Engineering. kreemer@unr.edu
|
|
Hans-Peter Plag, Research Professor, Nevada Bureau of Mines and Geology,
Mackay School of Earth Sciences and Engineering. hpplag@unr.edu
|
|
| Impact | Seismic hazard, understand dynamics of crustal extension, integration of seismology and geodesy, effects of seasonal hydrological mass changes on fault loading. |
| Statistics | Faculty Involved: 4
|
| Project Focus |
|
Updated: 12/12/2005
|
|
Remote Sensing of Water Clarity
Project Description
Monitoring the clarity of Lake Tahoe provides important information on pollution and environmental factors. Traditionally clarity is determined by dropping a bright white plate into the water and measuring the depth at which it disappears. Remote sensing instrumentation provide the ability to monitor clarity much more frequently and for the entire lake, not just one spot.This project seeks to establish methods of determining clarity from remote sensing imagery through correlaton with in-situ measurements.
|
Principal
Investigator(s) |
|
Wendy M. Calvin, Research Associate Professor, Geological Sciences,
College of Science. wcalvin@unr.edu
|
|
| Impact | New methods may allow better assessment of clarity changes with season as well as over time. |
| Project Duration | 2003-2005 |
| Project Focus |
|
Updated: 3/3/2005
|
|
Wildfire Effects On A Sierran Forest Soil: Setting A New Trajectory For Ecosystem Development
Project Description
We have recently been assessing the effects of wildfire on long-term nutrient budgets at a former burn site (1981) near Little Valley, Nevada. From measurements of stumps, present-day biomass, and nutrient inventories both in nearby unburned forests and in the shrub ecosystem now occupying the site, we have reconstructed pre-fire carbon and nutrient contents, estimated losses, and calculated the redistribution of nutrients due to the wildfire. Results suggest that losses of C from the site were dominated by post-fire salvage logging rather than direct combustion whereas the reverse was true for N. Results also indicate that N losses were completely replenished within 20 years through N fixation by Ceanothus vefutinus. Large differences in soil exchangeable Ca and Mg were observed 20 years after the fire, in contrast to some other studies where increases in exchangeable base canons after fire were short-term. Furthermore, the apparent enrichment of exchangeable Ca due to the fire far exceeded estimates of Ca contents in vegetation and forest floor before the fire. We hypothesize that a large proportion of the exchangeable Ca enrichment was due to a combination of Ca release from disintegration/dissolution of soil minerals and from organically-bound Ca in soils. Some research has shown that soil minerals can be decomposed during fire, but nutrient budgets routinely ignore organic Ca, Mg, and K pools in soils, focusing instead only on the exchangeable and mineral phases. One of the greatest sources of uncertainty in reconstructing nutrient budgets after wildfire is the change in soil nutrient fractions. It can be safely assumed in this region that all foliage and forest floor 2 components are consumed by intense stand-replacing wildfires, but assessing the organic matter combustion in soils is problematic.
|
Principal
Investigator(s) |
|
Dale Johnson, Professor of Forest Soil Chemistry, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. dwj@cabnr.unr.edu
|
|
W. Wally Miller, Professor of Soils and Hydrology, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. wilymalr@cabnr.unr.edu
|
|
| Project Focus |
|
Earth Science
|
|
Terrestrial Life
|
|
Fire
|
|
Updated: 12/20/2004
|
|
Wildfire In A Sierran Forest: Setting A New Trajectory for Ecosystem Development
Project Description
Catastrophic wildfire is increasing in forests of the Sierra Nevada and throughout the western US because of misguided policies of total fire suppression in the past. We hypothesize that wildfire resets the clock and establishes a new trajectory for ecosystem development in terms of carbon and nutrient cycling. Studies of wildfire are often plagued with uncertainties because of the lack of suitable control sites and pre-treatment sampling. We have an unparalleled opportunity to study the before and after effects of a recent wildfire in the Lake Tahoe Basin in Nevada. Nine of sixteen replicated plots previously laid out and sampled for a prescribed fire and harvesting study burned in an accidental wildfire set on 3 July 2002. Data from this site will allow us to test assumptions and algorithms previously used to reconstruct carbon and nutrient budgets on pre-existing wildfires and in extrapolating these results over the landscape. We propose to assess the effects of this wildfire on soil nutrient status, water quality, vegetation regrowth, carbon and nutrient budgets. Water quality measurements will include soil solution and surface runoff collections; soils and regenerating vegetation will be resampled twice during this study. We will extrapolate these results in time and space using a combination of simulation modeling and assessment of historic fire regimes in the region. This project will produce refereed journal publications and presentations at national meetings, outreach in the form of tours and class field trips, and the website will be updated with new information frequently. The project will employ several undergraduate students as hourly student employees and two graduate students as research assistants/interns dedicated to field data collection, laboratory analyses, data management, and information retrieval.
|
Principal
Investigator(s) |
|
Dale Johnson, Professor of Forest Soil Chemistry, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. dwj@cabnr.unr.edu
|
|
W. Wally Miller, Professor of Soils and Hydrology, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. wilymalr@cabnr.unr.edu
|
|
Roger F. Walker, Professor of Forestry, Natural Resources & Environmental Science,
College of Agriculture, Biotechnology, and Natural Resources. walker@cabnr.unr.edu
|
|
| Project Duration | 7/1/2004 - 6/30/2007 |
| Project Focus |
|
Earth Science
|
|
Terrestrial Life
|
|
Fire
|
|
Updated: 3/3/2005
|
|
