Geophysics and Seismology Commons^™

Teaching Geophysics With A Vertical-Component Seismometer, Kasper Van Wijk, Ted Channel, Karen Viskupic, Martin L. Smith

Geosciences Faculty Publications and Presentations

Earthquakes are some of the more dramatic expressions of the dynamics of our planet. The sudden release of stress built up slowly by tectonic or volcanic processes often has far-reaching consequences, and can be measured (in classrooms) around the world. This is one reason why designing and building seismometers has been a popular activity,^1,2 and why different versions of “Seismometer in Schools” projects thrive in the United States, Australia, and Europe. We present a cheap, robust, and easy-to-build seismometer—called the TC1 —to measure seismic displacements in the vertical direction. Its components are easy to obtain and assemble, yet the …

Single And Multi-Date Landsat Classifications Of Basalt To Support Soil Survey Efforts, Jessica J. Mitchell, Rupesh Shrestha, Carol A. Moore-Ellison, Nancy F. Glenn

Geosciences Faculty Publications and Presentations

Basalt outcrops are significant features in the Western United States and consistently present challenges to Natural Resources Conservation Service (NRCS) soil mapping efforts. Current soil survey methods to estimate basalt outcrops involve field transects and are impractical for mapping regionally extensive areas. The purpose of this research was to investigate remote sensing methods to effectively determine the presence of basalt rock outcrops. Five Landsat 5 TM scenes (path 39, row 29) over the year 2007 growing season were processed and analyzed to detect and quantify basalt outcrops across the Clark Area Soil Survey, ID, USA (4,570 km²). The …

Holocene Fire Occurrence And Alluvial Responses At The Leading Edge Of Pinyon–Juniper Migration In The Northern Great Basin, Usa, Kerrie N. Weppner, Jennifer L. Pierce, Julio L. Betancourt

Geosciences Faculty Publications and Presentations

Fire and vegetation records at the City of Rocks National Reserve (CIRO), south-central Idaho, display the interaction of changing climate, fire and vegetation along the migrating front of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma). Radiocarbon dating of alluvial charcoal reconstructed local fire occurrence and geomorphic response, and fossil woodrat (Neotoma) middens revealed pinyon and juniper arrivals. Fire peaks occurred ~10,700–9500, 7200–6700, 2400–2000, 850–700, and 550–400 cal yr BP, whereas ~9500–7200, 6700–4700 and ~1500–1000 cal yr BP are fire-free. Wetter climates and denser vegetation fueled episodic fires and debris flows during the …

High-Resolution Δ13CCarb Chemostratigraphy From Latest Guadalupian Through Earliest Triassic In South China And Iran, Vladimir Davydov

Geosciences Faculty Publications and Presentations

Large carbon cycle perturbations are associated with the end-Permian mass extinction and subsequent recovery, but Late Permian (Lopingian) carbon cycle dynamics prior to the mass extinction event remain poorly documented. Here we present a high-resolution δ¹³C_carb chemostratigraphic framework from latest Guadalupian to earliest Triassic time, calibrated with high-resolution conodont biostratigraphy and high-precision geochronology. We observe two large negative excursions in δ¹³C_carb, the first in uppermost Guadalupian strata and the second at the end of the Changhsingian stage, and between these events distinctive excursions from the middle Wuchiapingian to the early Changhsingian. The end-Changhsingian …

Anticipating Stream Ecosystem Responses To Climate Change: Toward Predictions That Incorporate Effects Via Land–Water Linkages, J. M. Davis, C. V. Baxter, E. J. Rosi-Marshall, J. L. Pierce, B. T. Crosby

Geosciences Faculty Publications and Presentations

Climate change (CC) is projected to increase the frequency and severity of natural disturbances (wildfires, insect outbreaks, and debris flows) and shift distributions of terrestrial ecosystems on a global basis. Although such terrestrial changes may affect stream ecosystems, they have not been incorporated into predictions of stream responses to CC. Here, we introduce a conceptual framework to evaluate to what extent responses of streams to CC will be driven by not only changes in thermal and hydrologic regimes, but also alterations of terrestrial processes. We focused on forested water-sheds of western North America because this region is projected to experience …

Detecting Geyser Activity With Infrasound, Jeffrey B. Johnson, J. F. Anderson, R. E. Anthony, M. Sciotto

Geosciences Faculty Publications and Presentations

We monitored geyser activity in the Lower Geyser Basin (LGB) of Yellowstone National Park with dual four-element microphone arrays separated by ~ 600 m. The arrays were independently used to identify incident coherent plane wave energy, then conjoint cross beam back-azimuths from the two arrays were used to precisely locate signal sources. During a week in August 2011 we located repeating infrasound events, peaked in energy between 1 and 10 Hz, originating from at least five independent geothermal features, including the episodically erupting Great Fountain, Fountain and Kaleidoscope Geysers, as well as periodic infrasound from nearby Botryoidal and persistent sound …

The First Second Of Volcanic Eruptions From The Erebus Volcano Lava Lake, Antarctica—Energies, Pressures, Seismology, And Infrasound, A. Gerst, M. Hort, R. C. Aster, J. B. Johnson, P. R. Kyle

Geosciences Faculty Publications and Presentations

[1] We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up to 40 m-diameter) bubble bursts from a persistent phonolite lava lake. These explosions are readily studied from the crater rim at ranges of less than 500 m and present an ideal opportunity to constrain the dynamics and mechanism of magmatic bubble bursts that can drive Strombolian and Hawaiian eruptions. We estimate the energy budget of the first second of a typical Erebus explosion as a function of time and energy type. We constrain …

A Latest Carboniferous Warming Spike Recorded By A Fusulinid-Rich Bioherm In Timor Leste: Implications For East Gondwana Deglaciation, Vladimir I. Davydov, David W. Haig, Eujay Mccartain

Geosciences Faculty Publications and Presentations

During the late Paleozoic and early Mesozoic Timor lay in the northern part of the north–south East Gondwana rift system along which the western margin of Australia later developed. Discovery of a latest Gzhelian bioherm in the central highlands of Timor Leste has implications for latest Carboniferous–earliest Permian climate history and deglaciation in basins further south in the rift system.

Limestone outcrop of the Maubisse Formation near the village of Kulau is recognized as a bioherm with a massive lower unit, including reef framework at the base, and a bedded grainstone upper unit. The bioherm developed on a basalt substrate …

Elastic Laboratory Measurements And Modeling Of Saturated Basalts, Ludmila Adam, Thomas Otheim

Geosciences Faculty Publications and Presentations

Understanding the elastic behavior of basalt is important to seismically monitor volcanoes, subsea basalts, and carbon sequestration in basalt. We estimate the elastic properties of basalt samples from the Snake River Plain, Idaho, at ultrasonic (0.8 MHz) and seismic (2–300 Hz) frequencies. To test the sensitivity of seismic waves to the fluid content in the pore structure, measurements are performed at three saturation conditions: saturated with liquid CO₂, water, and dry. When CO₂ replaces water, the P-wave velocity drops, on average, by 10%. Vesicles and cracks, observed in the rock microstructure, control the relaxation of pore-fluid pressures …