Physical Sciences and Mathematics Commons^™

Crustal Density Variation Of The Eastern U.S., Henglei Zhang, Dhananjay Ravat, Anthony R. Lowry

Earth and Environmental Sciences Research Data

EarthScope’s USArray Transportable Array (TA) has shortcomings for the purpose of interpreting geologic features of wavelengths less than the 70 km TA station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce non-uniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously-derived density variations of sedimentary basins, crustal Vp/Vs variation, Moho variation, and upper mantle density variation derived from body-wave imaging informed by surface wave tomography to estimate Vp/Vs. Although average densities and density contrasts for these seismic variations can be derived, …

Seismic Monitoring And Baseline Microseismicity In The Rome Trough, Eastern Kentucky, N. Seth Carpenter, Andrew S. Holcomb, Zhenming Wang, John B. Hickman, Edward W. Woolery

Report of Investigations--KGS

In the central and eastern United States, felt earthquakes likely triggered by fluid injection from oil and gas production or wastewater disposal have dramatically increased in frequency since the onset of the unconventional shale gas and oil boom. In the Rome Trough of eastern Kentucky, fracture stimulations and wastewater injection are ongoing and occur near areas of historical seismic activity. Unlike in surrounding and nearby states (Ohio, West Virginia, and Arkansas), in Kentucky, no seismic events related to subsurface fluid injections have been reported as felt or detected by regional seismic networks, including the Kentucky Seismic and Strong-Motion Network.

Oil …

Mineral Exploration And Sustainable Development: A Case Study In The Republic Of South Sudan, Cosmas Pitia Kujjo

Theses and Dissertations--Earth and Environmental Sciences

South Sudan, a new country formed in 2011, has been planning to develop its mineral sector by allocating exploration licenses to investors. This decision requires preliminary knowledge of geology and mineral occurrences, both of which are unavailable because the country has been engaged in a civil war for more than 50 years. Exploration of mineral resources in South Sudan has lagged behind its petroleum industry, except for artisanal gold mining, which is practiced intermittently by local communities. Freely available satellite gravity and remote-sensing data were used to map the basement architecture as well as zones of hydrothermal alteration in the …

An Update Of Seismic Monitoring And Research In The Vicinity Of The Paducah Gaseous Diffusion Plant: January 2013–December 2017, Zhenming Wang, Edward W. Woolery, N. Seth Carpenter

Report of Investigations--KGS

From January 2013 to December 2017, the Kentucky Geological Survey monitored earthquakes and conducted research on seismic hazards in the vicinity of the Paducah Gaseous Diffusion Plant, a former uranium enrichment facility, in western Kentucky. Fifteen earthquakes with magnitude greater than 3.0 occurred in the area during this period, and data were collected from the Central U.S. Seismic Observatory and the vertical seismic array at the gaseous diffusion plant. This monitoring improved our understanding of seismic-wave propagation through thick sediments and ground-motion site effects, as well as fault locations in the New Madrid Seismic Zone, ground-motion attenuation, and seismic-hazard assessment. …

The Undeniable Attraction Of Lunar Swirls, Dany Waller

Posters-at-the-Capitol Presentations

Lunar swirls are complex patterns on the Moon with distinct brightness signatures and magnetic characteristics. Current research has suggested that the formation of lunar swirls relies on local magnetic fields to shield impinging solar wind, based on a shift in electromagnetic wavelength peaks related to solar radiation and space weathering. Our research combined recent models and methods to characterize these anomalies at the surface of the Moon, exploring the effects of field strength and position. We have produced a high resolution map of a famous swirl named Reiner Gamma using magnetic dipole modeling. These maps and models are considered when …

Extension Of A Quaternary-Active Shear Zone Across The Reelfoot Fault Stepover Arm: Evidence From P- And Sh-Wave Seismic Reflection Imaging, Brooks Rosandich

Theses and Dissertations--Earth and Environmental Sciences

Many seismic hazard source parameters such as slip rate, total displacement, strain accommodation, geographic fault location, etc. are poorly constrained in the New Madrid seismic zone (NMSZ). This is in large part due to the masking effect of the thick Mississippi embayment sediment package on seismogenic structures and features. Consequently, much of the subsurface geologic characterization needed for understanding seismic hazard sources requires geophysical imaging. Recent seismic reflection surveys 12 km NE of the Reelfoot Fault stepover arm of the NMSZ have suggested a northeast-oriented transpressional fault zone extending across the Reelfoot Fault stepover arm where its dextral displacement at …

Integrated Seismic-Reflection And Microgravity Imaging Across The Southern Boundary Of The Charleston Uplift, New Madrid Seismic Zone, Usa, Drew D. Burford Jr.

Theses and Dissertations--Earth and Environmental Sciences

The Charleston Uplift (CU), a 30-km-long by 7-km-wide, N46°E-oriented subsurface geologic anomaly in the northern Mississippi embayment near Charleston, Missouri, exhibits up to 36 m of vertical relief across the Paleogene/Quaternary unconformity. Subsurface structural relief, along with the CU’s coincident boundary alignment with contemporary microseismicity and the New Madrid North Fault (NMNF), suggest a structural origin. Subsequent seismic soundings indicate vertical structural relief is present in Cretaceous and Paleozoic horizons, supporting the fault-controlled origin. The southern boundary (CU-s) had not been investigated, nor had any direct fault images been acquired. Integrated microgravity and seismic-reflection methods across the inferred CU-s establish …

Characterizations Of Linear Ground Motion Site Response In The New Madrid And Wabash Valley Seismic Zones And Seismicity In The Northern Eastern Tennessee Seismic Zone And Rome Trough, Eastern Kentucky, Nicholas Von Seth Carpenter

Theses and Dissertations--Earth and Environmental Sciences

The central and eastern United States is subject to seismic hazards from both natural and induced earthquakes, as evidenced by the 1811-1812 New Madrid earthquake sequence, consisting of at least three magnitude 7 and greater earthquakes, and by four magnitude 5 and greater induced earthquakes in Oklahoma since 2011. To mitigate seismic hazards, both earthquake sources and their effects need to be characterized.

Ground motion site response can cause additional damage to susceptible infrastructure and buildings. Recent studies indicate that Vs30, one of the primary site-response predictors used in current engineering practice, is not reliable. To investigate site response in …