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Articles 91 - 120 of 1923

Full-Text Articles in Sedimentology

Exploring Microplastic Concentrations And The Sedimentology Of San Diego's Offshore Benthic Environments, Rachel Sarner May 2024

Exploring Microplastic Concentrations And The Sedimentology Of San Diego's Offshore Benthic Environments, Rachel Sarner

Theses

Marine pollution studies are showing infiltration of plastic debris in remote parts of oceans including the deep sea. Microplastics (MPs) are being discovered not only in the ocean’s water column but also benthic sediments reaching thousands of meters in depth. This is the first study to analyze MP concentrations in conjunction with sedimentary characteristics from varying deep-sea environments (coastal, deep ocean, offshore terrace) in the Southern California Continental Borderland (CCB). Our goal for this study was to observe how the concentration and type (morphology, color, size) of microplastics varied with distance from shore, with water depth, and between different submarine …


Theory Of An Automatic Seepage Meter And Ramifications For Applications, V. A. Zlotnik, D. K. Solomon, D. P. Genereux, T. E. Gilmore, C. E. Humphrey, A. R. Mittelstet, A. V. Zlotnik May 2024

Theory Of An Automatic Seepage Meter And Ramifications For Applications, V. A. Zlotnik, D. K. Solomon, D. P. Genereux, T. E. Gilmore, C. E. Humphrey, A. R. Mittelstet, A. V. Zlotnik

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Depositional Facies Analysis Of The Cotton Valley Group Sandstones Of The Blackburn Field, Northern Louisiana Using Well Logs And Cores; Implications For Carbon Sequestration, Frederick Owusu May 2024

Depositional Facies Analysis Of The Cotton Valley Group Sandstones Of The Blackburn Field, Northern Louisiana Using Well Logs And Cores; Implications For Carbon Sequestration, Frederick Owusu

Electronic Theses and Dissertations

The Cotton Valley Group (CVG) consists of tight sandstones with heterogeneous reservoir properties due to variations in depositional environments and diagenesis, spanning across eastern Texas through the Florida panhandle. It has served as a hydrocarbon target since the 1940s, and with recent technological advances, there is renewed exploration of the tight reservoirs within the group. Across northern Louisiana, the CVG has moderate to good reservoir properties, whereas those south extending westward across the Sabine uplift into east Texas decrease in porosity and permeability. With reservoir depletion coupled with its relatively simple mineralogy, these sandstone units may serve as good, localized …


Investigating The Effects Of Suspended Algal Content, Dissolved Oxygen, And Temperature On A High-Frequency Acoustic Attenuation System In A Controlled Laboratory Environment, Noah Watson May 2024

Investigating The Effects Of Suspended Algal Content, Dissolved Oxygen, And Temperature On A High-Frequency Acoustic Attenuation System In A Controlled Laboratory Environment, Noah Watson

Honors Theses

The Single Frequency Acoustic Attenuation System (SFAAS) has been developed at the National Center for Physical Acoustics (NCPA). This system uses acoustic methods to monitor fine suspended sediment concentration in streams. Site-specific calibrations are necessary for this system, and previous research has indicated that algal concentration or dissolved oxygen concentration of water may affect collected data. Temperature, dissolved oxygen concentration, and fluorescence, used as a proxy for algal concentration, were monitored during this system’s use, and calibrations were derived to account for the effect of each of these variables on acoustic measurements. It has been shown that temperature has a …


Evaluating Reclaimed Mines And Heavy Metal Soil Contamination, Torin A. Matthews Apr 2024

Evaluating Reclaimed Mines And Heavy Metal Soil Contamination, Torin A. Matthews

ATU Scholars Symposium

Arkansas has a rich history of lead and zinc mining. While there are still some active mines, many historical mines have been abandoned and/or reclaimed. Although most reclamation procedures result in the burial and containment of target minerals, accessory minerals and elements can be leached out of waste materials/tailings piles and include heavy metals (i.e., Pb, As, Cd). We aim to evaluate the soil and watershed of a few abandoned/reclaimed mines in Pope County, AR, for the presence of heavy metals/source minerals. Soil and stream sediment geochemistry will be conducted using a portable x-ray fluorescence analyzer. Field work and sampling …


Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato Apr 2024

Applied Depositional Geosystems Of The Coos Bay Basin, Oregon: Organic Geochemistry, Maturation, Paleoenvironmental Reconstruction And Biostratigraphy Of The Coaledo Delta During The Middle Eocene Climatic Optimum (Meco), Allison K. Barbato

LSU Doctoral Dissertations

The Coos Bay Basin on the southwestern coast of Oregon is a forearc basin that contains exceptionally preserved Eocene to Miocene, tidal to wave-dominated, shallow deltaic to deep marine sediments of the Coaledo Delta. Coastal depositional environments are known to host source, reservoir, and seal rocks. Climate, topographic relief, and geographical position all play an important role in regional vegetation development and oceanic setting. This study assesses 84 outcrop and 12 core samples from Coos Bay for their organic geochemical characteristics and microfossil assemblage to provide source rock characterization information, organofacies descriptions, environmental reconstructions, and age control.

Results indicate the …


Lower Bound On Preserved Flood Duration In Fluvial Bedform Stratigraphy (Experimental Dataset), Robert C. Mahon, Vamsi Ganti, Madeline M. Kelley, Debsmita Das, Victoria Sanchez, Giancarlo Portocarrero, Mayson Fredricks Mar 2024

Lower Bound On Preserved Flood Duration In Fluvial Bedform Stratigraphy (Experimental Dataset), Robert C. Mahon, Vamsi Ganti, Madeline M. Kelley, Debsmita Das, Victoria Sanchez, Giancarlo Portocarrero, Mayson Fredricks

Lower Bound on Preserved Flood Duration in Fluvial Bedform Stratigraphy (experimental dataset)

This data is collected to assess the role of hydrograph timescale relative to dune migration on the preservation of cross sets in the stratigraphic record. The data presented here are of dune evolution under steady-state conditions, as well as three hydrographs of the same magnitude but varying timescales.

Methodology:

We collected data from four experiments tracking bedform evolution in a 22-m-long, 0.56-m-wide, 0.9-m-deep flume at the University of New Orleans Dynamics of Sedimentation laboratory. We conducted an equilibrium experiment (discharge value 0.027 m3/s) and three flood experiments, which were characterized by a symmetrical flood wave. In all flood experiments, the …


Stage And Discharge Prediction From Documentary Time-Lapse Imagery, Kenneth W. Chapman, Troy E. Gilmore, Mehrube Mehrubeoglu, Christian D. Chapman, Aaron R. Mittelstet, John E. Stranzl Jr. Mar 2024

Stage And Discharge Prediction From Documentary Time-Lapse Imagery, Kenneth W. Chapman, Troy E. Gilmore, Mehrube Mehrubeoglu, Christian D. Chapman, Aaron R. Mittelstet, John E. Stranzl Jr.

Conservation and Survey Division: Faculty and Staff Publications

Imagery from fixed, ground-based cameras is rich in qualitative and quantitative information that can improve stream discharge monitoring. For instance, time-lapse imagery may be valuable for filling data gaps when sensors fail and/or during lapses in funding for monitoring programs. In this study, we used a large image archive (>40,000 images from 2012 to 2019) from a fixed, ground-based camera that is part of a documentary watershed imaging project (https://plattebasintimelapse.com/). Scalar image features were extracted from daylight images taken at one-hour intervals. The image features were fused with United States Geological Survey stage and discharge data as response variables …


Analysis Of Legacy Gravity Data Reveals Sediment-Filled Troughs Buried Under Flathead Valley, Montana, Usa, Ali Gebril, Mohamed A. Khalil, Robert Matthew Joeckel, James Rose Feb 2024

Analysis Of Legacy Gravity Data Reveals Sediment-Filled Troughs Buried Under Flathead Valley, Montana, Usa, Ali Gebril, Mohamed A. Khalil, Robert Matthew Joeckel, James Rose

Conservation and Survey Division: Faculty and Staff Publications

Shallow, dominantly silt- and clay-filled erosional troughs in Quaternary sediments under the Flathead Valley (northwestern Montana, USA) are very likely to be hydraulic barriers limiting the horizontal flow of groundwater. Accurately mapping them is important because of increasing demand for groundwater.We used a legacy Bouguer gravity map measured in 1968. The directional derivatives of the map are computed, and the map was enhanced by implementing edge detection tools.We produced generalized derivative, maximum horizontal gradient, total gradient and tilt gradient maps through two-dimensional Fourier transform analysis. These maps were remarkably successful in locating buried troughs in the northern and northwestern parts …


Southern Maine, New Hampshire, And Northern Massachusetts Continental Shelf Geophysical Database: 2022 Field Campaign – Grain Size Data, Station Summaries, And Seafloor Photographs, Larry G. Ward, Rachel C. Morrison, Michael Bogonko Feb 2024

Southern Maine, New Hampshire, And Northern Massachusetts Continental Shelf Geophysical Database: 2022 Field Campaign – Grain Size Data, Station Summaries, And Seafloor Photographs, Larry G. Ward, Rachel C. Morrison, Michael Bogonko

Data Catalog

Presented in this data report are the geophysical data collected during a major field campaign in 2022, with the purpose of obtaining ground truth for the expansion and improvement of high-resolution surficial geology maps of the western Gulf of Maine (WGOM) and for the description of reference sites developed for future evaluations of acoustic systems (Ward et al., 2021a; 2021b). Data from the UNH Ocean Engineering 972 Hydrographic Field Course classes in 2021 and 2022 are also included. This expansion of the geophysical database is being used to verify seafloor classifications in previously mapped areas that lack sufficient data, and …


Landscape And Paleoenvironmental Change In Stream Valleys Of The Central Great Plains, North America During Marine Isotope Stage 3 (Ca. 59-27 Ka)., T. Layzell, K. Andrzejewski, R. D. Mandel, P.R. Hanson Jan 2024

Landscape And Paleoenvironmental Change In Stream Valleys Of The Central Great Plains, North America During Marine Isotope Stage 3 (Ca. 59-27 Ka)., T. Layzell, K. Andrzejewski, R. D. Mandel, P.R. Hanson

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Joint Interpretation Of Ert And Self-Potential Data To Characterize The Subsurface Geology And Hydrodynamics Along The Sutherland Supply Canal And Paxton Siphon Inlet, Paxton, Nebraska., M. K. Aboushanab, D. R. Hallum, R. M. Joeckel Jan 2024

Joint Interpretation Of Ert And Self-Potential Data To Characterize The Subsurface Geology And Hydrodynamics Along The Sutherland Supply Canal And Paxton Siphon Inlet, Paxton, Nebraska., M. K. Aboushanab, D. R. Hallum, R. M. Joeckel

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Multiscale Characterization Of Splays Produced By A Historic, Rain-On-Snow Flood On A Large Braided Stream (Platte River, Central Usa), J. T. Korus, R. M. Joeckel, A. R. Mittelstet, N. Shrestha Jan 2024

Multiscale Characterization Of Splays Produced By A Historic, Rain-On-Snow Flood On A Large Braided Stream (Platte River, Central Usa), J. T. Korus, R. M. Joeckel, A. R. Mittelstet, N. Shrestha

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Integrated Geochronological And Chemostratigraphic Study Of Middle Miocene Strata (Ogallala Group) At The Eastern Margin Of The North American Great Plains, J. J. Smith, Robert Matthew Joeckel, H. L. Field, G. A. Ludvigson, A. Moller, A. Layzell, S. T. Tucker Jan 2024

Integrated Geochronological And Chemostratigraphic Study Of Middle Miocene Strata (Ogallala Group) At The Eastern Margin Of The North American Great Plains, J. J. Smith, Robert Matthew Joeckel, H. L. Field, G. A. Ludvigson, A. Moller, A. Layzell, S. T. Tucker

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Improving Accessibility And Understanding: Studying The Impact Of Human Activities And Dam Removals On Anadromous Fish Species In The Pacific Northwest, Adia F. Bennett Jan 2024

Improving Accessibility And Understanding: Studying The Impact Of Human Activities And Dam Removals On Anadromous Fish Species In The Pacific Northwest, Adia F. Bennett

Scripps Senior Theses

Human activities in North American watersheds have significantly impacted anadromous fish, causing some species of salmon and steelhead to become threatened and endangered. These fish hold ecological, cultural, and economic importance, yet factors such as habitat destruction, overfishing, pollution, climate change, and hydroelectric dams continue to degrade populations. Dams are particularly harmful to anadromous fish, sparking a recent movement advocating for dam removals. This study uses NOAA’s 2022 Biological Viability Assessment to examine the response of anadromous fish to recent dam removals in the Pacific Northwest. Four populations were selected to analyze due to their interaction with sites that had …


Locating And Assessing Oregon Trail Ruts With Aerial Stereophotographs, Satellite Imagery And Lidar, P.R. Hanson, Robert Matthew Joeckel, L. M. Howard Jan 2024

Locating And Assessing Oregon Trail Ruts With Aerial Stereophotographs, Satellite Imagery And Lidar, P.R. Hanson, Robert Matthew Joeckel, L. M. Howard

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Wetlands In The Nebraska Sandhills, Nawaraj Shrestha Jan 2024

Wetlands In The Nebraska Sandhills, Nawaraj Shrestha

Conservation and Survey Division: Faculty and Staff Publications

Infographic titled “Status of Wetlands in the Nebraska Sandhills” showing multiple maps and charts. The top left features a color-coded wetland persistence map where blue indicates more consistent wetlands and red indicates intermittent wetlands. Additional inset maps show a regional zoom and a U.S. location map highlighting Nebraska. A large scatter plot displays wetland occurrence percentages over time using MODIS (green points) and Sentinel (blue points) satellite data from 2000 to 2024. Text explains how wetlands vary seasonally and annually and how satellite imagery tracks these changes. A smaller bottom chart shows long-term wetland trends, noting increasing occurrence since 1984. …


Leveraging High Resolution Classifications And Random Forests For Hindcasting Decades Of Mesic Ecosystem Dynamics In The Landsat Time Series, N. E. Kolarik, Nawaraj Shrestha, T. Caughlin, J. S. Brandt Jan 2024

Leveraging High Resolution Classifications And Random Forests For Hindcasting Decades Of Mesic Ecosystem Dynamics In The Landsat Time Series, N. E. Kolarik, Nawaraj Shrestha, T. Caughlin, J. S. Brandt

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Nebraska Statewide Groundwater-Level Monitoring Report 2023, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Nawaraj Shrestha, Jeffrey Westrop Jan 2024

Nebraska Statewide Groundwater-Level Monitoring Report 2023, Aaron R. Young, Mark E. Burbach, Sue Olafsen Lackey, Robert Matthew Joeckel, Nawaraj Shrestha, Jeffrey Westrop

Conservation and Survey Division: Faculty and Staff Publications

This report is a synthesis of groundwater-level monitoring programs in Nebraska. It is a continuation of the series of annual reports and maps produced by the Conservation and Survey Division (CSD) of the University of Nebraska in cooperation with the U.S. Geological Survey (USGS) since the 1950s. Groundwater-level monitoring began in Nebraska in 1930 to survey the state’s groundwater resources and observe changes in its availability on a regular basis. The CSD and USGS cooperatively developed, maintained, and operated an observation-well network throughout the state. These two agencies were responsible for collecting and archiving this information, and for making it …


Transient Electromagnetic (Tem) Survey For Targeted Drilling On The Kurtzhals Property, Cedar County, Nebraska, Jesse Korus, Katherine (Katie) Cameron, Michele Waszgis Jan 2024

Transient Electromagnetic (Tem) Survey For Targeted Drilling On The Kurtzhals Property, Cedar County, Nebraska, Jesse Korus, Katherine (Katie) Cameron, Michele Waszgis

Conservation and Survey Division: Faculty and Staff Publications

The Kurtzhals property is in Section 19, Township 30N, Range 3 in Cedar County, Nebraska. The present land use is agricultural row crop, but past use included hog production. Two active irrigation wells are located on adjacent properties to the west and southwest. An irrigation well was installed in the northwest corner of the property in 2022. Due to the low yield (300 gallons per minute) of this well, Mr. Kurtzhals seeks to install an additional irrigation well to supplement the first. Several unsuccessful test holes had been drilled prior to the present survey. The purpose of this survey was …


Zircon Luminescence Dating Re-Visited, C. Schmidt, T. Halter, P.R. Hanson, A. Ulianov, B. Putlitz, G. E. King, S. Kreutzer Jan 2024

Zircon Luminescence Dating Re-Visited, C. Schmidt, T. Halter, P.R. Hanson, A. Ulianov, B. Putlitz, G. E. King, S. Kreutzer

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Age Dating Young Groundwater: How To Determine Groundwater Age From Environmental Tracer Data, D. K. Solomon, T. E. Gilmore Jan 2024

Age Dating Young Groundwater: How To Determine Groundwater Age From Environmental Tracer Data, D. K. Solomon, T. E. Gilmore

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.


Recent Paleolimnological History Of Jackson Lake, Grand Teton National Park, Wyoming (Usa), Hillary Johnson Jan 2024

Recent Paleolimnological History Of Jackson Lake, Grand Teton National Park, Wyoming (Usa), Hillary Johnson

Theses and Dissertations--Earth and Environmental Sciences

This study utilizes a recently acquired, high-resolution CHIRP seismic reflection dataset and a deepwater sediment core to analyze the recent stratigraphy of Jackson Lake (Wyoming, USA). The western shoreline of Jackson Lake is situated adjacent to the Teton fault, a down-to-the-east normal fault that produces the spectacular high topography of Grand Teton National Park. The sediments of Jackson Lake are underexplored and consequently, their value as indicators of hydroclimatic and tectonic changes is unknown. Here, the sedimentary fill of Jackson Lake is explored as a natural archive of environmental change, specifically in reference to the influence of human outlet engineering …


Re-Examination Of A Middle Mississippian Carbonate Mud-Mound Complex From The Fort Payne Formation In South-Central, Kentucky, Maxwell Mickelson Jan 2024

Re-Examination Of A Middle Mississippian Carbonate Mud-Mound Complex From The Fort Payne Formation In South-Central, Kentucky, Maxwell Mickelson

Theses and Dissertations--Earth and Environmental Sciences

This study examines the origin of a 213-m (700-ft) long, Middle Mississippian, carbonate “mud-mound complex” in the Fort Payne Formation of south-central Kentucky. The complex’s well-exposed, easily accessible, and well-preserved nature provides an opportunity to understand how mounds like this developed during a time of sediment starvation, basinward of the largely abandoned Borden-Grainger Delta complex.

The mound complex is formed of small, accretionary mounds that accreted onto the flanks of an eroded structural high and onto the backs of each other, apparently for protection from storms. Each sub-mound is composed of micrite-rich wackestone, comprising one of two biofacies: 1) alternating …


High Resolution Sedimentary Investigations Of Extant Lakes In North America, John Dilworth Jan 2024

High Resolution Sedimentary Investigations Of Extant Lakes In North America, John Dilworth

Theses and Dissertations--Earth and Environmental Sciences

Investigation of past lake environments forms the discipline of paleolimnology. Paleolimnological studies seek to evaluate geophysical, geochemical, and ecological proxies and indicators contained within lake sediment archives. Using these potential stores of high-resolution environmental information, questions regarding climate, biological, and geochemical changes experienced by a lake and its watershed can be investigated. This dissertation research utilized lake sediment records from two lakes within North America to study different aspects of environmental change. This dissertation consists of three separate studies presented in three chapters.

Chapter Two presents a retrospective environmental assessment of Jackson Lake, Wyoming to investigate the impacts of dam …


Evaluating Field Evidence Of Fine-Grained Sediment Abrasion In Gravel-Bedded Rivers: A Case Study Of The Lillooet And Suiattle Rivers In The Cascade Volcanic Arc (British Columbia, Canada, And Washington, Usa), Devin T. Johnson Jan 2024

Evaluating Field Evidence Of Fine-Grained Sediment Abrasion In Gravel-Bedded Rivers: A Case Study Of The Lillooet And Suiattle Rivers In The Cascade Volcanic Arc (British Columbia, Canada, And Washington, Usa), Devin T. Johnson

Honors Theses

Steep, gravel-bedded rivers are important sites for studying gravel abrasion, where material transported as bed load experiences size reduction and rounding due to grain-to-grain collisions. Studying fine sediment (diameter) abrasion and grain shape changes in fluvial systems is more challenging due to difficulties in quantifying sediment shape at this scale, but it is assumed that fine particles traveling in suspension do not experience abrasion. Improvements in particle characterization technology now allow for the accurate, rapid quantification of particle shape for sediments as fine as 0.8 μm through dynamic image analysis. Here we use the Camsizer X2 (CX2) to test the …


A Comparison Of Sediment Accumulation Effectiveness Behind Beaver Dam Analogues, One Rock Dams, And Post-Assisted Log Structures On East Foster Creek, Douglas County, Wa, Griffin Hansen Jan 2024

A Comparison Of Sediment Accumulation Effectiveness Behind Beaver Dam Analogues, One Rock Dams, And Post-Assisted Log Structures On East Foster Creek, Douglas County, Wa, Griffin Hansen

All Master's Theses

Waterways are valuable resources for communities and habitats, but are subject to degradation in the form of incision. This is a type of streambed erosion where streams narrow and deepen. Sediment control dams were placed on East Foster Creek in Douglas County, WA to control incision following the 2020 Pearl Hill fire. This study examined sediment capture in the ponds behind these dams, which included beaver dam analogues (BDAs), one rock dams (ORDs), and post-assisted log structures (PALS). Sediment capture may be influenced by several factors, including dam type, height, width, distance between dams, vegetation, land use, topography, soil type, …


Beach Erosion And Recovery Since Hurricane Ivan In 2004 Along A Headland-Bay Coast In Treasure Beach, Jamaica, Elandé Engelbrecht Jan 2024

Beach Erosion And Recovery Since Hurricane Ivan In 2004 Along A Headland-Bay Coast In Treasure Beach, Jamaica, Elandé Engelbrecht

Graduate Theses/Dissertations

Anthropogenic climate change is causing sea-level rise and shoreline changes that threaten the environment and economy of coastal communities in Caribbean Island nations. To assess this risk, this study quantifies shoreline changes at Treasure Beach in St. Elizabeth Parish on the south coast of Jamaica from 2001 to 2023. The effects of storm events on erosion were also assessed. Over 10 km of shoreline are assessed with about half being sandy pocket beaches ranging from 300 to 900 m in length, separated by rocky headlands and beach rock outcrops. Sand beach erosion trends since 2001 are assessed for seven sandy …


The Effect Of Seasonal Ice Cover Duration On Shoreline Erosion In Lake Michigan, Ryan S. Navarre Jan 2024

The Effect Of Seasonal Ice Cover Duration On Shoreline Erosion In Lake Michigan, Ryan S. Navarre

Dissertations, Master's Theses and Master's Reports

Shoreline erosion in Lake Michigan has been a significant concern for coastal management. Promoting coastal stability and resilience is paramount to protecting these environments, especially amid climate change. While several factors are key in understanding shoreline erosion, seasonal ice cover duration is a prominent yet understudied factor in the Great Lakes region. Here, the relationship between ice cover duration and shoreline erosion rates is assessed across 7 regions of Lake Michigan. An ice cover duration dataset was created for Lake Michigan for 2011 – 2020 and its shorelines were digitized for years with available high-resolution aerial imagery. The statistical relationship …


Small-Strain Site Response Of Soft Soils In The Sacramento-San Joaquin Delta Region Of California Conditioned On Vₛ₃₀ And Mhvsr, Tristan E. Buckreis, Jonathan P. Stewart, Scott J. Brandenberg, Pengfei Wang Jan 2024

Small-Strain Site Response Of Soft Soils In The Sacramento-San Joaquin Delta Region Of California Conditioned On Vₛ₃₀ And Mhvsr, Tristan E. Buckreis, Jonathan P. Stewart, Scott J. Brandenberg, Pengfei Wang

Civil & Environmental Engineering Faculty Publications

Sites located in the Sacramento-San Joaquin Delta region of California typically have peaty-organic soils near the ground surface, which are characteristically soft, with shear wave velocities as low as 30 m/s. These unusually soft geotechnical conditions, which are outside the range of applicability of existing ergodic site amplification models, can be anticipated to produce significant site effects during earthquake shaking. We evaluate site response for 36 seismic stations in the Delta region using non-ergodic methods with low-amplitude ground motion data. We model first-order site effects using a period-dependent relation conditioned on the 30 m time-averaged shear wave velocity (V …