Geology topics

David Hoffman

Publications and source records attributed to David Hoffman.

6 recordsLinked to original sources

USGS2026

Waterfowl move less in heterogeneous and human-populated landscapes, with implications for spread of avian influenza viruses

Animal movements contribute to the spread of infectious diseases and are driven in part by environmental conditions. We investigated the links among the environment, animal movement, and infectious disease dynamics in waterfowl, which are among the primary wildlife hosts of avian influenza viruses. By combining telemetry data on 4606 individuals from 26 waterfowl species with data on land cover, weather, and vegetation, we found that waterfowl moved less in areas of higher land cover heterogeneity and higher human population density. Moreover, predicted waterfowl movement distances were weakly but positively correlated with distances between detections of H5N1 highly pathogenic avian influenza in wild waterfowl, suggesting that environmental conditions might contribute to the spread of this disease via their effects on bird movements. By considering wildlife movements alongside other drivers of infectious disease dynamics, such as livestock production and human mobility, we move closer to predicting outbreaks and informing interventions.

Ecology Letters↗

USGS2016

St. Louis area earthquake hazards mapping project; seismic and liquefaction hazard maps

We present probabilistic and deterministic seismic and liquefaction hazard maps for the densely populated St. Louis metropolitan area that account for the expected effects of surficial geology on earthquake ground shaking. Hazard calculations were based on a map grid of 0.005°, or about every 500 m, and are thus higher in resolution than any earlier studies. To estimate ground motions at the surface of the model (e.g., site amplification), we used a new detailed near‐surface shear‐wave velocity model in a 1D equivalent‐linear response analysis. When compared with the 2014 U.S. Geological Survey (USGS) National Seismic Hazard Model, which uses a uniform firm‐rock‐site condition, the new probabilistic seismic‐hazard estimates document much more variability. Hazard levels for upland sites (consisting of bedrock and weathered bedrock overlain by loess‐covered till and drift deposits), show up to twice the ground‐motion values for peak ground acceleration (PGA), and similar ground‐motion values for 1.0 s spectral acceleration (SA). Probabilistic ground‐motion levels for lowland alluvial floodplain sites (generally the 20–40‐m‐thick modern Mississippi and Missouri River floodplain deposits overlying bedrock) exhibit up to twice the ground‐motion levels for PGA, and up to three times the ground‐motion levels for 1.0 s SA. Liquefaction probability curves were developed from available standard penetration test data assuming typical lowland and upland water table levels. A simplified liquefaction hazard map was created from the 5%‐in‐50‐year probabilistic ground‐shaking model. The liquefaction hazard ranges from low (<40% of area expected to liquefy) in the uplands to severe (>60% of area expected to liquefy) in the lowlands. Because many transportation routes, power and gas transmission lines, and population centers exist in or on the highly susceptible lowland alluvium, these areas in the St. Louis region are at significant potential risk from seismically induced liquefaction and associated ground deformation

Alabama, Arkansas, Illinois, Indiana, Iowa, Kentuc↗

USGS2007

Effects of dietary selenium on tissue concentrations,pathology, oxidative stress, and immune function in common eiders (Somateria mollissima)

Common eiders ( Somateria mollissima ) were fed added Se (as L-selenomethionine) in concentrations increasing from 10 to 80 ppm in a pilot study (Study 1) or 20 (low exposure) and up to 60 (high exposure) ppm Se in Study 2. Body weights of Study 1 ducks and high-exposure ducks in Study 2 declined rapidly. Mean concentrations of Se in blood reached 32.4 ppm wet weight in Study 1 and 17.5 ppm wet weight in high-exposure birds in Study 2. Mean Se concentrations in liver ranged from 351 (low exposure, Study 2) to 1252 ppm dry weight (Study 1). Oxidative stress was evidenced by Se-associated effects on glutathione metabolism. As Se concentrations in liver increased, Se-dependent glutathione peroxidase activity, glutathione reductase activity, oxidized glutathione levels, and the ratio of hepatic oxidized to reduced glutathione increased. In Study 2, the T-cell-mediated immune response was adversely affected in high-exposure eiders, but ducks in the low-exposure group exhibited evidence of an enhanced antibody-mediated immune response. Gross lesions in high-exposure ducks included emaciation, absence of thymus, and loss of nails from digits. Histologic lesions included severe depletion of lymphoid organs, hepatopathy, and necrosis of feather pulp and feather epithelium. Field studies showed that apparently healthy sea ducks generally have higher levels of Se in liver than healthy fresh-water birds, but lower than concentrations found in our study. Data indicate that common eiders and probably other sea ducks possess a higher threshold, or adverse effect level, for Se in tissues than fresh-water species. However, common eiders developed signs of Se toxicity similar to those seen in fresh-water birds.

Journal of Toxicology and Environmental Health, Pa↗

USGS2007

Geotechnical reconnaissance of the Mississippi River Delta flood-protection system after Hurricane Katrina

This article presents the post-Hurricane Katrina conditions of the flood-protection system of levees and floodwalls that failed in the environs of the Mississippi River Delta and New Orleans, La. Damage conditions and suggested mechanisms of failure are presented from the geotechnical point of view.

Louisiana↗

USGS2007

Analysis of the Interstate 10 Twin Bridge’s collapse during Hurricane Katrina: Chapter 3D in Science and the storms-the USGS response to the hurricanes of 2005

The Interstate 10 Twin Span Bridge over Lake Pontchartrain north of New Orleans, La., was rendered completely unusable by Hurricane Katrina. The cause of the collapse of the bridges generated great interest among hydrologists and structural engineers as well as among the general public. What made this case study even more important was the fact that two nearby bridges sustained the effects of the same storm surge and suffered only light damage. Lessons learned from this investigation are invaluable to maintaining the safety of many of the Nation's coastal and river-crossing bridges.

Louisiana↗

USGS2002

Geologic Map of the Scott City 7.5-Minute Quadrangle, Scott and Cape Girardeau Counties, Missouri

The Scott City quadrangle is located at the northern end of the Mississippi embayment (fig. 1). The quadrangle contains parts of three physiographic features: the abandoned channel of the ancestral Mississippi River, the Benton Hills, and the flood plain of the ancestral Ohio River and modern Mississippi River. These features are largely the manifestation of the Quaternary evolution of the Mississippi and Ohio Rivers, the chronology and analysis of which has been discussed by Fisk (1944), Saucier (1968, 1974, 1994), Guccione and others (1990), Madole and others (1991), Autin and others (1991), Porter and Guccione (1994), and Blum and others (1995a,b).

IMAP↗