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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon Graham, Marco Guzmán-Speziale, Douglas Hernandez, Vladimir Kostoglodov, Peter Lafemina, Neal Lord, Cécile Lasserre, Hélène Lyon-Caen, Manuel Rodriguez Maradiaga, Robert Mccaffrey, Enrique Molina, Jeffrey Rivera, Robert Rogers, Alejandra Staller
Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon Graham, Marco Guzmán-Speziale, Douglas Hernandez, Vladimir Kostoglodov, Peter Lafemina, Neal Lord, Cécile Lasserre, Hélène Lyon-Caen, Manuel Rodriguez Maradiaga, Robert Mccaffrey, Enrique Molina, Jeffrey Rivera, Robert Rogers, Alejandra Staller
Geology Faculty Publications and Presentations
We use continuous and campaign measurements from 215 GPS sites in northern Central America and southern Mexico to estimate coseismic and afterslip solutions for the 2009 Mw = 7.3 Swan Islands fault strike-slip earthquake and the 2012 Mw = 7.3 El Salvador and Mw = 7.4 Guatemala thrust-faulting earthquakes on the Middle America trench. Our simultaneous, time-dependent inversion of more than 350 000 daily GPS site positions gives the first jointly consistent estimates of the coseismic slips for all three earthquakes, their combined time-dependent post-seismic effects and secular station velocities corrected for both the coseismic and post-seismic deformation. Our geodetic …
Decadal Topographic Change In The Mcmurdo Dry Valleys Of Antarctica: Thermokarst Subsidence, Glacier Thinning, And Transfer Of Water Storage From The Cryosphere To The Hydrosphere, J. S. Levy, Andrew G. Fountain, M. K. Obryk, J. Telling, Craig Glennie, M. Gooseff, David J. Van Horn
Decadal Topographic Change In The Mcmurdo Dry Valleys Of Antarctica: Thermokarst Subsidence, Glacier Thinning, And Transfer Of Water Storage From The Cryosphere To The Hydrosphere, J. S. Levy, Andrew G. Fountain, M. K. Obryk, J. Telling, Craig Glennie, M. Gooseff, David J. Van Horn
Geology Faculty Publications and Presentations
Recent local-scale observations of glaciers, streams, and soil surfaces in the McMurdo Dry Valleys of Antarctica (MDV) have documented evidence for rapid ice loss, glacial thinning, and ground surface subsidence associated with melting of ground ice. To evaluate the extent,magnitude, and location of decadal-scale landscape change in the MDV, we collected airborne lidar elevation data in 2014–2015 and compared these data to a 2001–2002 airborne lidar campaign. This regional assessment of elevation change spans the recent acceleration of warming and melting observed by long-term meteorological and ecosystem response experiments, allowing us to assess the response of MDV surfaces to warming …
Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon E. Graham, Robert Mccaffrey, Multiple Additional Authors
Gps Constraints On Deformation In Northern Central America From 1999 To 2017, Part 1 – Time-Dependent Modelling Of Large Regional Earthquakes And Their Post-Seismic Effects, A. Ellis, Charles Demets, P. Briole, Beatriz Cosenza, Omar Flores, Shannon E. Graham, Robert Mccaffrey, Multiple Additional Authors
Geology Faculty Publications and Presentations
We use continuous and campaign measurements from 215 GPS sites in northern Central America and southern Mexico to estimate coseismic and afterslip solutions for the 2009 Mw = 7.3 Swan Islands fault strike-slip earthquake and the 2012 Mw = 7.3 El Salvador and Mw = 7.4 Guatemala thrust-faulting earthquakes on the Middle America trench. Our simultaneous, time-dependent inversion of more than 350 000 daily GPS site positions gives the first jointly consistent estimates of the coseismic slips for all three earthquakes, their combined time-dependent post-seismic effects and secular station velocities corrected for both the coseismic and post-seismic …
Electron Backscatter Diffraction (Ebsd) Study Of Seven Heavily Metamorphosed Chondrites: Deformation Systematics And Variations In Pre-Shock Temperature And Post-Shock Annealing, Alexander M. Ruzicka, Richard C. Hugo
Electron Backscatter Diffraction (Ebsd) Study Of Seven Heavily Metamorphosed Chondrites: Deformation Systematics And Variations In Pre-Shock Temperature And Post-Shock Annealing, Alexander M. Ruzicka, Richard C. Hugo
Geology Faculty Publications and Presentations
We used electron backscatter diffraction (EBSD) methods to study the crystallography of olivine and other minerals in seven heavily metamorphosed (petrographic type 6 or 6/7) but variably shocked ordinary chondrites from the H (Kernouvé, Portales Valley), L (Leedey, Bruderheim, Morrow County, Park) and LL (Miller Range (MIL) 99301) groups. MIL 99301 contains a large clast that was analyzed separately. Mesoscale (EBSD) data support and extend inferences based on microscale (TEM) observations and provide good evidence that chondrites were shock-deformed at different temperatures and were variably annealed (sintered) after deformation. Various EBSD deformation intensity metrics adequately and quantitatively represent olivine deformation …
Contrasting Governance Learning Processes Of Climate-Leading And -Lagging Cities: Portland, Oregon, And Phoenix, Arizona, Usa, Jonathan H. Fink
Contrasting Governance Learning Processes Of Climate-Leading And -Lagging Cities: Portland, Oregon, And Phoenix, Arizona, Usa, Jonathan H. Fink
Geology Faculty Publications and Presentations
The contrasting histories and political ecologies of two U.S. cities—Portland Oregon and Phoenix Arizona—shed light on their ability to learn from and influence the climate governance of their peers. Portland's populace, political leadership, and business sectors are motivated by environmental and social values, resulting in a collective sense of responsibility for fixing global problems like climate change. The city's pioneering land-use policies, green infrastructure, and multimodal transportation systems solidify its place at the climate action forefront. In contrast, libertarian Phoenix prioritizes real estate, efficient government, tourism, and protection of individual rights—the antithesis of Portland's altruism. However, because Phoenix's economic success …
Transient Reactivation Of A Deep-Seated Landslide By Undrained Loading Captured With Repeat Airborne And Terrestrial Lidar, Adam M. Booth, Justin Mccarley, Jason Hinkle, Jean-Paul Ampuero, Michael P. Lamb
Transient Reactivation Of A Deep-Seated Landslide By Undrained Loading Captured With Repeat Airborne And Terrestrial Lidar, Adam M. Booth, Justin Mccarley, Jason Hinkle, Jean-Paul Ampuero, Michael P. Lamb
Geology Faculty Publications and Presentations
Landslides reactivate due to external environmental forcing or internal mass redistribution, but the process is rarely documented quantitatively. We capture the three-dimensional, 1-m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar. Undrained loading by two debris flows in the landslide’s head, rather than external forcing, triggered reactivation. After that loading, the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping. The displacement field over those 2 years implies that the slip surface gained 1 kPa of shear strength, which was likely accomplished by …
Drivers Of Solar Radiation Variability In The Mcmurdo Dry Valleys, Antarctica, Maciej K. Obryk, Andrew G. Fountain, Peter T. Doran
Drivers Of Solar Radiation Variability In The Mcmurdo Dry Valleys, Antarctica, Maciej K. Obryk, Andrew G. Fountain, Peter T. Doran
Geology Faculty Publications and Presentations
Annually averaged solar radiation in the McMurdo Dry Valleys, Antarctica has varied by over 20 W m−2 during the past three decades; however, the drivers of this variability are unknown. Because small differences in radiation are important to water availability and ecosystem functioning in polar deserts, determining the causes are important to predictions of future desert processes. We examine the potential drivers of solar variability and systematically eliminate all but stratospheric sulfur dioxide. We argue that increases in stratospheric sulfur dioxide increase stratospheric aerosol optical depth and decrease solar intensity. Because of the polar location of the McMurdo Dry Valleys …
Winter Rain Versus Snow In Headwater Catchments: Responses Of An Unconfined Pumice Aquifer, South-Central Oregon, Usa, Michael L. Cummings, David A. Eibert
Winter Rain Versus Snow In Headwater Catchments: Responses Of An Unconfined Pumice Aquifer, South-Central Oregon, Usa, Michael L. Cummings, David A. Eibert
Geology Faculty Publications and Presentations
Winter precipitation in two headwaters catchments (elevation ~1600 m) in the rain shadow of the Cascades volcanic arc in south-central Oregon normally falls as snow. However, in water year 2015, winter precipitation fell mainly as rain. An eight year study of the unconfined pumice aquifer allowed inter-annual comparison of groundwater recharge during the freshet and discharge during the growing season. During these water years precipitation ranged from 67% (WY2014) to 132% (WY2017) of the 30 year average, and included the rain dominated winter of WY2015 when precipitation during the water year was 98% of the 30 year average. Change in …
A Shift From Drought To Extreme Rainfall Drives A Stable Landslide To Catastrophic Failure, Alexander L. Handwerger, Mong-Han Haung, Eric Jameson Fielding, Adam M. Booth, Roland Burgmann
A Shift From Drought To Extreme Rainfall Drives A Stable Landslide To Catastrophic Failure, Alexander L. Handwerger, Mong-Han Haung, Eric Jameson Fielding, Adam M. Booth, Roland Burgmann
Geology Faculty Publications and Presentations
The addition of water on or below the earth’s surface generates changes in stress that can trigger both stable and unstable sliding of landslides and faults. While these sliding behaviours are well-described by commonly used mechanical models developed from laboratory testing (e.g., critical-state soil mechanics and rate-and-state friction), less is known about the field-scale environmental conditions or kinematic behaviours that occur during the transition from stable to unstable sliding. Here we use radar interferometry (InSAR) and a simple 1D hydrological model to characterize 8 years of stable sliding of the Mud Creek landslide, California, USA, prior to its rapid acceleration …
Glacier Recession And The Response Of Summer Streamflow In The Pacific Northwest United States, 1960–2099, Chris Frans, Erkan Istanbulluoglu, Dennis P. Lettenmaier, Andrew G. Fountain, Jon L. Riedel
Glacier Recession And The Response Of Summer Streamflow In The Pacific Northwest United States, 1960–2099, Chris Frans, Erkan Istanbulluoglu, Dennis P. Lettenmaier, Andrew G. Fountain, Jon L. Riedel
Geology Faculty Publications and Presentations
The Pacific Northwest is the most highly glacierized region in the conterminous United States (858 glaciers; 466 km2). These glaciers have displayed ubiquitous patterns of retreat since the 1980s mostly in response to warming air temperatures. Glacier melt provides water for downstream uses including agricultural water supply, hydroelectric power generation, and for ecological systems adapted to cold reliable streamflow. While changes in glacier area have been studied within the region over an extended period of time, the hydrologic consequences of these changes are not well defined. We applied a high‐resolution glacio‐hydrological model to predict glacier mass balance, glacier area, and …
A Simplified, Object-Based Framework For Efficient Landslide Inventorying Using Lidar Digital Elevation Model Derivatives, Michael D. Bunn, Ben A. Leshcinsky, Michael J. Olsen, Adam M. Booth
A Simplified, Object-Based Framework For Efficient Landslide Inventorying Using Lidar Digital Elevation Model Derivatives, Michael D. Bunn, Ben A. Leshcinsky, Michael J. Olsen, Adam M. Booth
Geology Faculty Publications and Presentations
Landslide inventory maps are critical to understand the factors governing landslide occurrence and estimate hazards or sediment delivery to channels. Numerous semi-automated approaches for landslide inventory mapping have been proposed to improve the efficiency and objectivity of the process, but these methods have not been widely adopted by practitioners because of the use of input parameters without physical meaning, a lack of transparency in machine-learning based mapping techniques, and limitations in resulting products, which are not ordinarily designed or tested on a large-scale or in diverse geologic units. To this end, this work presents a new semi-automated method, called the …
New Geologic Mapping Of The Northwestern Willamette Valley, Oregon, And Its American Viticultural Areas (Avas)— A Foundation For Understanding Their Terroir, Ray E. Wells, Ralph Haugerud, Alan Niem, Lina Ma, Ian Madin, Russell Evarts
New Geologic Mapping Of The Northwestern Willamette Valley, Oregon, And Its American Viticultural Areas (Avas)— A Foundation For Understanding Their Terroir, Ray E. Wells, Ralph Haugerud, Alan Niem, Lina Ma, Ian Madin, Russell Evarts
Geology Faculty Publications and Presentations
A geologic map of the greater Portland, Oregon, metropolitan area is planned that will document the region’s complex geology (currently in review: “Geologic map of the greater Portland metropolitan area and surrounding region, Oregon and Washington,” by Wells, R.E., Haugerud, R.A., Niem, A., Niem, W., Ma, L., Evarts, R., Madin, I., and others). The map, which is planned to be published as a U.S. Geological Survey Scientific Investigations Map, will consist of 51 7.5′ quadrangles covering more than 2,500 square miles, and it will represent more than 100 person-years of geologic mapping and studies. The region was mapped at the …
The Littlefield Rhyolite And Associated Mafic Lavas: Bimodal Volcanism Of The Columbia River Magmatic Province, With Constraints On Age And Storage Sites Of Grande Ronde Basalt Magmas, Brian Mcculloch Webb, Martin J. Streck, William C. Mcintosh, Mark L. Ferns
The Littlefield Rhyolite And Associated Mafic Lavas: Bimodal Volcanism Of The Columbia River Magmatic Province, With Constraints On Age And Storage Sites Of Grande Ronde Basalt Magmas, Brian Mcculloch Webb, Martin J. Streck, William C. Mcintosh, Mark L. Ferns
Geology Faculty Publications and Presentations
We present data that distinguishes the long-known Littlefield Rhyolite of eastern Oregon (northwestern United States) into two distinct, voluminous, Snake River–type, high-temperature rhyolite lava packages that erupted in short sequence overk.y., with minimum volumes of 100 and 150 km3 respectively, contemporaneous with flood basalt volcanism of the Grande Ronde Basalt phase of the Columbia River Basalt Group. Contemporaneity of rhyolites with flood basalts is exceptionally demonstrated within the Malheur Gorge by intercalated mafic units belonging to the Grande Ronde Basalt that are stratigraphically constrained by underlying and overlying Littlefield Rhyolite flows, and the underlying Dinner Creek Tuff (unit 1). Our …