Physical Sciences and Mathematics Commons^™

Comparisons Of Gravity Anomalies At Pseudofaults, Fracture Zones, And Nontransform Discontinuities From Fast To Slow Spreading Areas, Sarah E. Kruse, Sarah F. Tebbens, David F. Naar, Qingyuan Y. Lou, Robert T. Bird

Geology Faculty Publications

Published mechanisms for rift tip propagation at spreading centers include extensional deformation and an initial period of slow spreading. We investigate whether the gravity signal and inferred crustal structure at pseudofaults formed in medium to superfast spreading environments resemble the gravity signal at fracture zones or nontransform discontinuities formed in slow spreading environments. We find that altimetry-based gravity anomalies on the Mathematician, Bauer, Easter, Juan Fernandez, and northern Chile Ridge pseudofaults, located in 75–150 mm/yr (full rate) seafloor spreading environments, are similar in amplitude and form to Atlantic fracture zones with 20–30 mm/yr spreading rates. A 5–15 mGal positive mantle …

Beneficial Use Of Dredge Material For Tampa Bay Bottom Habitat Restoration, Tampa Baywatch, Inc.

Reports

A brief description of each site is included in the text, with contact information where available. The 11 sites were selected due to their location, potential for restoration, active projects under development, public safety issues and proximity to a source of fill material. Again, the survey is intended to be a starting point. All sites will require an extensive evaluation, including opportunities for public input, before restoration plans can move forward.

Aseismic Inflation Of Westdahl Volcano, Alaska, Revealed By Satellite Radar Interferometry, Zhong Lu, Charles Wicks, Daniel Dzurisin, Wayne Thatcher, Jeffrey T. Freymuller, Stephen R. Mcnutt, Dorte Mann

School of Geosciences Faculty and Staff Publications

Westdahl volcano, located at the west end of Unimak Island in the central Aleutian volcanic arc, Alaska, is a broad shield that produced moderate-sized eruptions in 1964, 1978–79, and 1991–92. Satellite radar interferometry detected about 17 cm of volcano-wide inflation from September 1993 to October 1998. Multiple independent interferograms reveal that the deformation rate has not been steady; more inflation occurred from 1993 to 1995 than from 1995 to 1998. Numerical modeling indicates that a source located about 9 km beneath the center of the volcano inflated by about 0.05 km³ from 1993 to 1998. On the basis of the …

Comparative Ecosystem Analysis Of Hydrologic Restoration Of Tates Hell Swamp, Chris Robert, Thomas Crisman, Loren Anderson, Carolyn Kendell

School of Geosciences Faculty and Staff Publications

No abstract provided.

Seagrass And Caulerpa Monitoring In Hillsborough Bay Eleventh Annual Report, City Of Tampa Department Of Sanitary Sewers

Reports

This is the eleventh annual report to FDER to satisfy the requirements set forth in specific condition #14 of FDER construction permit DO29-1845321B.

The City of Tampa, Bay Study Group (BSG), has monitored the effects of sewage pollution abatement in Hillsborough Bay since 1976. During the mid 1980's, water quality improvements and evidence of minor seagrass revegetation in Hillsborough Bay prompted the BSG to initiate a seagrass study to compliment other programs assessing the environmental status of Hillsborough Bay.

Results Of The City Of Tampa Surface Water Compliance Monitoring Program For The Year 1999 And Examination Of Long-Term Water Quality And Biological Indicator Trends In Hillsborough Bay, City Of Tampa Department Of Sanitary Sewers

Reports

This report is submitted to Florida Department of Environmental Regulation (FDER) to satisfy the requirements set forth in specific condition No. 14 of Hookers Point WWTP permit No. D029-184532B. The report is based on data obtained by the City of Tampa (COT) compliance water quality monitoring program approved under construction permit DC29-152799 and the report also includes examination of long-term trends for water quality parameters and biological indicators collected by the City of Tampa Bay Study Group and the Environmental Protection Commission of Hillsborough County (EPC).

State Of Tampa Bay 1999, Tampa Bay Regional Planning Council (Tbrpc), Agency On Bay Management

Reports

This is the thirteenth edition of the "State of Tampa Bay" Report. It has been prepared by the Agency on Bay Management and funded by the Tampa Bay Regional Planning Council. The Report's primary purpose is to inform our legislators and the general public about the projects and programs underway around Tampa Bay and in its watershed. Summaries of programs of Baywide significance have been contributed by our most important Bay stewards. Reports from several organizations and agencies recap their activities in 1999 and describe planned projects for 2000. Many of these are actually updates, as these entities have contributed …

Application Of Wave-Theoretical Seismoacoustic Models To The Interpretation Of Explosion And Eruption Tremor Signals Radiated By Pavlof Volcano, Alaska, Milton A. Garces, Stephen R. Mcnutt, Roger A. Hansen, John C. Eichelberger

School of Geosciences Faculty and Staff Publications

Tremor and explosion signals recorded on September 29 during the Fall 1996 Pavlof eruption are interpreted using video images, field observations, and seismic data. Waveform analysis of tremor and explosions provided estimates of the melt's volcano-acoustic parameters and the magma conduit dimensions. Initial mass fractions of 0.25% water and 0.025% carbon dioxide in the melt can explain the resonance characteristics of the tremor and explosion pulses inferred from seismic data. The magma conduit is modeled as a three-section rectangular crack. We infer that the tremor-radiating region consists of the lowermost two sections, both with cross-sectional areas of ∼10 m^{2 …}

Present-Day Motion Of The Sierra Nevada Block And Some Tectonic Implications For The Basin And Range Province, North American Cordillera, Timothy H. Dixon, Meghan Miller, Frederic Farina, Hongzhi Wang, Daniel Johnson

School of Geosciences Faculty and Staff Publications

Global Positioning System (GPS) data from five sites on the stable interior of the Sierra Nevada block are inverted to describe its angular velocity relative to stable North America. The velocity data for the five sites fit the rigid block model with rms misfits of 0.3 mm/yr (north) and 0.8 mm/yr (east), smaller than independently estimated data uncertainty, indicating that the rigid block model is appropriate. The new Euler vector, 17.0°N, 137.3°W, rotation rate 0.28 degrees per million years, predicts that the block is translating to the northwest, nearly parallel to the plate motion direction, at 13–14 mm/yr, faster than …

Neotectonics Of Puerto Rico And The Virgin Islands, Northeastern Caribbean, From Gps Geodesy, Pamela E. Jansma, Glen S. Mattioli, Alberto Lopez, Charles Demets, Timothy H. Dixon, Paul Mann, Eric Calais

School of Geosciences Faculty and Staff Publications

The boundary between the North American and Caribbean plates is characterized primarily by left-lateral motion along predominantly east-west striking faults. Seismicity and marine geophysical survey data are consistent with at least two, and possibly three, microplates in the diffuse boundary zone in the northeastern Caribbean: (1) the Gonave, (2) the Hispaniola, and (3) the Puerto Rico-northern Virgin Islands (PRVI). We discuss results from GPS geodetic measurements acquired since 1994 to test the microplate hypothesis, define PRVI translation and rotation within the boundary zone, and constrain PRVI neotectonics. GPS-derived velocities are analyzed with respect to both North American and Caribbean plate …

Gps Geodetic Constraints On Caribbean-North America Plate Motion, Charles Demets, Pamela E. Jansma, Glen S. Mattioli, Timothy H. Dixon, Fred Farina, Roger Bilham, Eric Calais, Paul Mann

School of Geosciences Faculty and Staff Publications

We describe a model for Caribbean plate motion based on GPS velocities of four sites in the plate interior and two azimuths of the Swan Islands transform fault. The data are well fit by a single angular velocity, with average misfits approximately equal to the 1.5–3.0 mm yr⁻¹ velocity uncertainties. The new model predicts Caribbean-North America motion ∼65% faster than predicted by NUVEL-1A, averaging 18–20±3 mm yr⁻¹ (2σ) at various locations along the plate boundary. The data are best fit by a rotation pole that predicts obliquely convergent motion along the plate boundary east of Cuba, but are …

On Defining The “Edge” Of A Seagrass Bed, R. Virnstein, W. M. Avery, J.O. R. Johansson

Reports

Need for a definition of the “edge” of a seagrass bed: The edge is the basis for: 1. Total acreage of seagrass. 2. Change detection, both by groundbased transects and mapping from aerial photos. 3. Seagrass restoration targets; assessments of progress may be based on a comparison of the deep edge of grass beds to the target depth.

Water Depth (Mtl) At The Deep Edge Of Seagrass Meadows In Tampa Bay Measured By Gps Carrier-Phase Processing: Evaluation Of The Technique, J.O. R. Johansson

Reports

The Tampa Bay Estuary Program (TBEP) has selected seagrass restoration target depths for each major bay segment at which adequate light conditions (20.5% of subsurface PAR irradiance) shall be maintained to ensure seagrass growth and the long-term Tampa Bay seagrass restoration goal of 15,400 ha. To evaluate the progress towards the goal, information on today’s seagrass depth distribution is needed. Specifically, a need exists to accurately determine the water depth at the deep edge of the meadows for each seagrass species in different sections of the bay. A relatively simple technique that provides elevation measurements, related to the mean tide …

2000 File Geodatabase Containing Aerial Photos, Pete Reehling, Richard Mckenzie, City Of Tampa Department Of Sanitary Sewers Bay Study Group

Images

The Bay Study Group was created by the City of Tampa in 1976 to monitor the effects of pollution abatement that occurred in Hillsborough Bay when the city’s wastewater treatment plant was upgraded from primary to advanced treatment in 1979. The Bay Study Group documented a remarkable restoration of water quality parameters and biological indicators in Hillsborough Bay from the mid 1980s until 2009, when it was disbanded. This zip Geodatabase file contains the aerial photos for the year 2000.

2000 File Geodatabase Containing Photo Point Locations, Aerial Photos, And Flight Maps, City Of Tampa Department Of Sanitary Sewers Bay Study Group, Pete Reehling, Richard Mckenzie

Data Sets

The Bay Study Group was created by the City of Tampa in 1976 to monitor the effects of pollution abatement that occurred in Hillsborough Bay when the city’s wastewater treatment plant was upgraded from primary to advanced treatment in 1979. The Bay Study Group documented a remarkable restoration of water quality parameters and biological indicators in Hillsborough Bay from the mid 1980s until 2009, when it was disbanded. This zip Geodatabase file contains the photo point locations, aerial photos, and flight maps for the year 2000.

Geologic Factors Controlling Patterns Of Small‐Volume Basaltic Volcanism: Application To A Volcanic Hazards Assessment At Yucca Mountain, Nevada, Charles B. Connor, John A. Stamatakos, David A. Ferrill, Brittain E. Hill, Goodluck I. Ofoegbu, Michael Conway, Budhi Sagar, John Trapp

School of Geosciences Faculty and Staff Publications

The proposed high‐level radioactive waste repository at Yucca Mountain, Nevada, is located within an active volcanic field. Probabilistic volcanic hazard models for future eruptions through the proposed repository depend heavily on our understanding of the spatial controls on volcano distribution at a variety of scales. On regional scales, Pliocene‐Quaternary volcano clusters are located east of the Bare Mountain fault. Extension has resulted in large‐scale crustal density contrast across the fault, and vents are restricted to low‐density areas of the hanging wall. Finite element modeling indicates that this crustal density contrast can result in transient pressure changes of up to 7 …

Annual Update Of Tampa Bay Chlorophyll-A Concentrations 2000, J. O.R. Johansson

Reports

The amount of phytoplankton present in Tampa Bay waters can be estimated from measurements of the green plant pigment chlorophyll-a. Phytoplankton is one of several major forms of plants that exist in Tampa Bay and most other estuaries. Other major plant types are submerged seagrass, macro-algae and benthic micro-algae. The different plants can be viewed as being in competition with each other for required resources, such as light and nutrients. Studies conducted in urbanized estuaries have shown that excessive loading of nitrogen generally is accompanied by an increase of phytoplankton and macro-algae, including epiphytic and drift macro-algae, and by a …

Development, Management And Economy Of Show Caves, Arrigo A. Cigna, Ezio Burri

International Journal of Speleology

The problems concerning the development of show caves are here considered by taking into account different aspects of the problem. A procedure to carry out an Environmental Impact Assessment (EIA) has been established in the last decade and it is now currently applied. Such an assessment starts with a pre-operational phase to obtain sufficient information on the undisturbed status of a cave to be developed into a show cave. Successively a programme for its development is established with the scope to optimise the intervention on the cave at the condition that its basic environmental parameters are not irreversibly modified. The …

Verification Of The Causes Of Glaciations And Sea Level Changes Using The Records Of Calcite Speleothems, Y. Shopov, D. Stoykova, L. Tsankov, M. Sanabria, J. Lundberg, L. Georgiev, P. Forti, D. Georgieva

International Journal of Speleology

The luminescence of calcite speleothems displays an exponential dependence on soil temperature unless there is a dense cover of forest over the cave to dampen it. This relationship is determined primarily by the strength of solar visible and infrared radiation. It is suggested that, as a consequence, the microzonal variations of luminescence often found in speleothems can be used as a proxy index of Solar Insolation. The luminescence solar insolation proxy record of a speleothem from Jewel Cave, South Dakota, USA, was found to display millenial and centennial cycles in the record. It exhibits a rapid increase in solar insolation …

Révision De Quelques Hypothèses Sur Le Creusement Karstique, Jacques Choppy

International Journal of Speleology

Quite often, as we know better karst phenomena and the evolution of the karst environment, several hypotheses on speleogenesis appeared to be flimsy. Some of these hypotheses, concerning processes playing a part in the creation of karst forms, exceed the limits of their field. Others suggest hydraulic mechanisms, and interventions of geological or geographical factors likely to be questioned. Hypotheses relating to the evolution of karst, as well as the classification of karst types, suffer from the lack of an analytical approach. However, some of these hypotheses still have an important place in the current vision of speleologists and karstologists.

The Influence Of Cave Tourism On Co2 And Temperature In Baiyun Cave, Hebei, China, Linhua Song, Wei Xiaoning, Liang Fuyuan

International Journal of Speleology

Baiyun Cave in Hebei Province is one of the main show caves in North China. The speleothem landscape is wonderful, but strongly weathered. In order to set up the relationship between visitor flow and CO₂ content and temperature, these parameters were measured at observation sites No. 1 and No. 2 in the tourist peak period of May Day Holiday from May 1 to May 7, 2000. and general tourist season August and October, 2000. The results show that visitor flow strongly affects the fluctuations of cave CO₂ content and temperature, that the cave topography and dimensions affect the …

Is It Always Dark In Caves?, Giovanni Badino

International Journal of Speleology

Underground natural sources of visible light are considered. The main light producer is Cerenkov radiation emitted in air, water and rock by cosmic ray muons, that depends, in a complex way, on shape of mountain and of caves. In general the illumination increases linearly with the cavity dimensions. Other light sources are from secondary processes generated by radioactive decays in rock from minerals luminescence. The natural light fluxes in caves are in general easy to detect but are not used from underground life.

New Rare Cave Minerals From The Perolas-Santana Karst System (São Paulo State, Brazil), Paolo Forti, Ermanno Galli, Antonio Rossi

International Journal of Speleology

The Perolas-Santana karst system (São Paulo State, Brazil) has been partially studied from the mineralogical point of view. The present paper will contribute to the knowledge of the minerals in these caves, describing the occurrence of euhedral celestite crystals and of a rather rare mineral for a cavern environment: lithiophorite. Thanks to these new discoveries the Perolas-Santana karst system becomes one of the most important in Brazil from a mineralogical point of view. Finally, the result of the chemical analyses carried out on this newly discovered Monoxyhydroxide put in evidence a zonation in the distribution of the different elements which …