Geology topics

Research about Greeley, Colorado

Source-linked reports with geographic coverage including Greeley, Colorado.

4 recordsLinked to original sources

USGS2023

Investigations of ambient noise velocity variations in a region of induced seismicity near Greeley, Colorado

Wastewater injection has induced earthquakes in Northeastern Colorado since 2014. We apply ambient noise correlation techniques to determine temporal changes in seismic velocities in the region. We find no clear correlation between seismic velocity fluctuations and either injection volumes or seismicity patterns. We do observe apparent annual variations in velocity that may be associated with hydrologic loading or thermoelastic strain. In addition, we model uniform and vertically localized velocity perturbations, and measure the velocity change with 1D synthetic seismograms. Our results indicate that our methods underestimate the known velocity change, especially at shorter station distances and when variations are restricted to a horizontal layer. If injection does cause measurable velocity changes, its effect is likely diluted in cross correlations due to its localized spatial extent around injection wells.

Colorado↗

USGS2016

Rapid response, monitoring, and mitigation of induced seismicity near Greeley, Colorado

On 1 June 2014 (03:35 UTC), an M w 3.2 earthquake occurred in Weld County, Colorado, a historically aseismic area of the Denver–Julesburg basin. Weld County is a prominent area of oil and gas development, including many high‐rate class II wastewater injection wells. In the days following the earthquake, the University of Colorado, with support from the U.S. Geological Survey and Incorporated Research Institutions for Seismology–Portable Array Seismic Studies of the Continental Lithosphere, rapidly deployed six seismic stations to characterize the seismicity associated with the 1 June earthquake (the Greeley sequence) and to investigate its possible connection to wastewater disposal. The spatial and temporal proximity of earthquakes to a high‐rate wastewater disposal well strongly suggests these earthquakes were induced. Scientific communication between the university, state agencies, and the energy industry led to rapid mitigation strategies to reduce the occurrence of further earthquakes. Mitigation efforts included implementing a temporary moratorium on injection at the well, cementing the bottom portion of the disposal well to minimize hydrologic connectivity between the disposal formation and the underlying crystalline basement, and subsequently allowing injection to resume at lower rates. Following the resumption of wastewater disposal, microseismicity was closely monitored for both increases in earthquake rate and magnitude. Following mitigation efforts, between 13 August 2014 and 29 December 2015, no earthquakes larger than M 1.5 occurred near the Greeley sequence. This study demonstrates that a detailed and rapid characterization of a seismic sequence in space and time relative to disposal, combined with collaboration and communication between scientists, regulators, and industry, can lead to objective and actionable mitigation efforts that potentially reduced the rate of earthquakes and the possible generation of larger earthquakes.

Colorado↗

USGS2004

Analysis of MASTER thermal data in the Greeley area of the Front Range Urban Corridor, Colorado — Delineation of sites for infrastructure resource characterization

Sand and soils southwest of Greeley, Colorado, were characterized for mineral composition and industrial quality. Radi-ance data from the thermal channels of the MASTER simulator were calibrated using estimated atmospheric parameters. Chan-nel emissivities were approximated using an estimated ground temperature. Subsequently, a decorrelation algorithm was used to calculate inverse wave emissivity images. Six soil classes, one vegetation class, water, and several small classes were defined using an unsupervised classification algorithm. Ground covered by each of the derived emissivity spectral classes was studied using color-infrared air photos, color-infrared composite MAS-TER data, geologic maps, NASA/JPL Airborne Visible and Infra-red Imaging Spectrometer (AVIRIS) data, and field examination. Spectral classes were characterized by their responses and related to their mineral content through field examination. Classes with a minimum at channel 44, and having a similar spectral shape to quartz, field checked as containing abundant quartz. Classes with a minimum at channel 45, and having a spectral shape similar to the sheet minerals, were found in the field to contain abundant mica and clay. Sandy soil was found to have a positive slope at the longer wavelengths; the more clay rich soils had a negative slope. Spectra with a strong downturn at channel 50 generally indicated low vegetation cover, whereas an upturn indicated more vegetation cover. Mapping revealed a range of classified soils with varying amounts of quartz, silt, clay, and plant humus. Sand and gravel operations along the St. Vrain River, gravel lots, and some fields spectrally classified as quartz-rich sands were confirmed through field examination. Other fields mapped as sandy soils, ranging from quartz-rich sandy soil to quartz-rich silt-sand soil with clay. Flood plains mapped as sandy-silty-organic-rich clay. The city of Greeley contained all classes of materials, with the sand classes mapping as various types of asphalt. Abundant quartz gravel was apparent within the asphalt during field check-ing. The clay classes mapped silt-clay soils in areas of irrigated grass landscaping, some fields, and roofing materials.

Colorado↗

USGS1981

Effects of a cattle feedlot on ground-water quality in the South Platte River Valley near Greeley, Colorado

Changes in water quality in an alluvial aquifer resulting from the operation of a feedlot stocked with 90,000 cattle have been minimal. Monitoring water quality in 19 observation wells from April 1974, prior to the operation of the feedlot, to June 1978, after about 4 years of operation, indicates that chloride concentrations have increased slightly in one well downgradient from a runoff-retention pond. Chemical analyses of water from two lysimeters installed in the unsaturated zone indicate that leachate from the feedlot has percolated to a depth of at least 5 feet but has not percolated to a depth of 20 feet. The small changes in ground-water quality caused by the feedlot are likely the result of the limited available recharge, a relatively impermeable manure pack, soil clogging under the cattle pens resulting in slow vertical movement of leachate through the unsaturated zone, soil clogging under the unlined runoff-retention ponds, and denitrification in the unsaturated zone.

Colorado↗