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Effective Elastic Thickness Of The Lithosphere Along The Easter Seamount Chain, Sarah E. Kruse, Zhengro J. Liu, David F. Naar, Robert A. Duncan

Geology Faculty Publications

Bathymetry and gravity data collected during Legs 5, 6, and 7 of the 1993 GLORIA Expedition and the recently released 2-min altimetry-derived global gravity grid are used to determine the effective elastic thickness of the lithosphere along the Easter Seamount Chain (ESC). Forward modeling, admittance, and coherence methods yield consistent results. With the exception of the eastern and western ends of the ESC the effective elastic thickness along the chain is ∼1–4 km. The thin elastic thickness for the majority of the ESC seamounts is compatible with a young seafloor age at the time of loading derived from new radiometric …

Evaluation Of Constructed Wetlands On Phosphate Mined Lands In Florida, G. R. Best, M. T. Brown, Thomas Crisman, Keven L. Erwin, D. A. Graetz, K. R. Reddy, H. Kale, P. Pritchard, T. M. Missimer, C. W. Walker, A. Owosina, M. J. Deuver

School of Geosciences Faculty and Staff Publications

Summarizing research conducted from June 1993 to May 1995 on hydrology, soils, water quality, and aquatic fauna on phosphate mined lands in Florida.

An Evaluation Of Plant Community Structure, Fish And Benthic Meio- And Macrofauna As Success Criteria For Reclaimed Wetlands, Thomas Crisman, William J. Streever, John H. Kiefer, David L. Evans

School of Geosciences Faculty and Staff Publications

As a result of legislative action in 1975 (Florida Administrative Code Section 16C-16, 16C-17), landscape reclamation is required on all lands mined for phosphate in the State of Florida. Between 1975 and 1991, for example, approximately 40,000 ha of land in Florida were strip mined for phosphate and thus subject to provisions of this legislation. In excess of 2,700 ha of mitigation wetlands have been constructed as part of the land reclamation effort, but the degree to which these systems mimic both the structural and functional properties of natural wetlands is poorly known.

There has been a great diversity in …

Linking Transport Infrastructure Investments And Economic Development In Sub-Saharan Africa, Ambe J. Njoh

School of Geosciences Faculty and Staff Publications

The study explores the link between investments in transportation infrastructure, operationalized in terms of road density, and economic development, defined in terms of gross domestic product per capita (GDP/Cap), in sub-Saharan Africa (SSA). The findings support the hypothesis of a positive association between the two variables. The association is stronger for paved, than for all, roads in general. Furthermore, a negative but statistically insignificant relationship is observed between unpaved roads and economic development. Thus, economic development is a function more of quality, than quantity of roads in SSA. Therefore, a more judicious use of the scarce resource of sub-Saharan African …

Relative Motion Between The Caribbean And North American Plates And Related Boundary Zone Deformation From A Decade Of Gps Observations, Timothy H. Dixon, Frederic Farina, Charles Demets, Pamela Jansma, Paul Mann, Eric Calais

School of Geosciences Faculty and Staff Publications

Global Positioning System (GPS) measurements in 1986, 1994, and 1995 at sites in Dominican Republic, Puerto Rico, Cuba, and Grand Turk define the velocity of the Caribbean plate relative to North America. The data show eastward motion of the Caribbean plate at a rate of 21 ± 1 mm/yr (1 standard error ) in the vicinity of southern Dominican Republic, a factor of 2 higher than the NUVEL-1A plate motion model prediction of 11 ± 3 mm/yr. Independent measurements on San Andres Island, and an Euler vector derived from these data, also suggest a rate that is much higher than …

Continuous Monitoring Of Surface Deformation At Long Valley Caldera, California, With Gps, Timothy H. Dixon, Ailin Mao, Marcus Bursik, Michael Heflin, John Langbein, Ross Stein, Frank Webb

School of Geosciences Faculty and Staff Publications

Continuous Global Positioning System (GPS) measurements at Long Valley Caldera, an active volcanic region in east central California, have been made on the south side of the resurgent dome since early 1993. A site on the north side of the dome was added in late 1994. Special adaptations for autonomous operation in remote regions and enhanced vertical precision were made. The data record ongoing volcanic deformation consistent with uplift and expansion of the surface above a shallow magma chamber. Measurement precisions (1 standard error) for “absolute” position coordinates, i.e., relative to a global reference frame, are 3–4 mm (north), 5–6 …

Constraints On Present-Day Shortening Rate Across The Central Eastern Andes From Gps Data, Lisa Leffler, Seth Stein, Ailin Mao, Timothy H. Dixon, Michael A. Ellis, Leonidas Ocola, I. Selwyn Sacks

School of Geosciences Faculty and Staff Publications

Two years of continuous GPS data from several sites in South America indicate that Arequipa in the southern Peruvian Andes has a velocity of 13±3 mm/yr (two standard errors) to the northeast with respect to stable South America. We interpret these data as reflecting a combination of elastic strain accumulation associated with a locked Nazca-South America subduction zone and a small amount of crustal shortening across the fold and thrust belt on the eastern margin of the Andes. Models of elastic strain accumulation for fully locked and partly locked subduction zones constrain shortening in the eastern Andes to 0–3 mm/yr …

Kilauea Volcano Provides Hot Seismic Data For Joint Japanese-U.S. Experiment, Stephen R. Mcnutt, Y. Ida, B. A. Chouet, P. Okubo, J. Oikawa, G. Saccorotti

School of Geosciences Faculty and Staff Publications

A team of 25 researchers from the United States, Japan, and Italy joined the staff of the Hawaiian Volcano Observatory (HVO) from January 8 through February 9, 1996, to make the most detailed seismic recordings on Kilauea Volcano ever. One-hundred-sixteen portable seismographs were installed in and near Kilauea Crater in Hawaii Volcanoes National Park as a joint Japanese-U.S. research project to record volcanic earthquakes and tremor. The importance of these events has long been recognized, but their origin remains poorly understood due to inadequate network coverage and limitations of the analog instrumentation used in the past.

On February 1, a …

A Gps Estimate Of Relative Motion Between North And South America, Timothy H. Dixon, Ailin Mao

School of Geosciences Faculty and Staff Publications

GPS velocity data are used to estimate the Euler vector describing rigid body motion of North America relative to South America. Assuming the boundary between the North and South American plates is located near the Fifteen Twenty fracture zone in the equatorial Atlantic, the Euler vector predicts extension across the Royal Trough up to 1 mm/yr, and convergence across the Barracuda Ridge at about 2 mm/yr, in agreement with geological estimates averaged over tens of millions of years. Further west, convergence between North and South America at rates up to 8 mm/yr may contribute to deformation of the Caribbean plate …

New Constraints On Source Processes Of Volcanic Tremor At Arenal Volcano, Costa Rica, Using Broadband Seismic Data, John P. Benoit, Stephen R. Mcnutt

School of Geosciences Faculty and Staff Publications

Broadband seismic data recorded 2.3 km from the active vent of Arenal Volcano, Costa Rica, provide new constraints on tremor source processes. Arenal's tremor contains as many as seven harmonics, whose frequencies vary temporally by up to 75 percent, from initial values of 1.9 Hz for the first peak immediately following explosive eruptions to 3.2–3.5 Hz several minutes later. We infer that gas bubble concentration is variable within the conduit and also changes as a function of time, thereby changing the acoustic velocity. We infer that the source is a shallow, 200–660 m-long, vertically oriented 1-D resonator with matched boundary …

Magnetic Surveys Help Reassess Volcanic Hazards At Yucca Mountain, Nevada, Charles B. Connor, Sammantha Lane-Magsino, John A. Stamatakos, Ronald H. Martin, Peter C. Lafemina, Brittain E. Hill, Steve Lieber

School of Geosciences Faculty and Staff Publications

Natural disasters like volcanic eruptions occur infrequently, but if they occur near nuclear power plants or high‐level radioactive waste repositories, local and global communities can be threatened. Ideally, such facilities should be constructed only where geologic risk is very low.

Estimating the probabilities of such events requires a comprehensive understanding of site geology and the geologic processes operating in the site region on timescales of 104 to 107years. In light of these requirements, geologists and geophysicists must continually improve techniques for site characterization.

Are Troglobitic Taxa Troglobiomorphic? A Test Using Phylogenetic Inference, Laure Desutter-Grandcolas

International Journal of Speleology

Obligate cave dwelling organisms are frequently characterised by a peculiar morphological syndrome, named troglomorphosis or troglobiomorphosis. This hypothesis, which deals with the evolutionary influence of the subterranean environment on cave organisms is far from being universally accepted. Yet it has been adopted by many authors and is often included in the definitions of the current classification of cave taxa. In this paper I present a test of the troglobiomorphosis hypothesis, using the case study of the cricket clade Amphiacustae (Orthoptera, Grylloidea, Phalangopsidae). Such a test preliminarily requires that observations of the habitat of the taxa (achieved on present-day populations) are …

The Hawaiian Cave Planthoppers (Homoptera: Fulgoroidea: Cixiidae) - A Model For Rapid Subterranean Speciation?, Hannelore Hoch

International Journal of Speleology

After the successful colonization of a single ancestral species in the Hawaiian Islands, planthoppers of the cixiid genus Oliarus underwent intensive adaptive radiation resulting in 80 described endemic species. Oliarus habitats range from montaneous rain forests to dry coastal biotopes and subterranean environments. At least 7 independant evolutionary lines represented by different species have adapted to lava tubes on Molokai (1), Maui (3), and Hawaii Island (3). Behavioral and morphological studies on one of these evolutionary lines on Hawaii Island, the blind, flight- and pigmentless Oliarus polyphentus have provided evidence for reproductive isolation between allopatric populations which may in fact …

Climatic Fluctuations And Tropical Troglobitic Evolution, Pedro Gnaspini

International Journal of Speleology

No abstract provided.

Genetic Divergence And Evolutionary Times: Calibrating A Protein Clock For South-European Stenasellus Species (Crustacea Isopoda), Valerio Ketmaier, Roberto Argano, Marina Cobolli, Elvira De Matthaeis

International Journal of Speleology

We studied genetic divergence in a group of exclusively stygobiont isopods of the family Stenasellidae. In particular, we assessed evolutionary relationships among several populations of Stenasellus racovitzai and Stenasellus virei. To place this study in a phylogenetic context. we used another species of Stenasellus, S. assorgiai, as an outgroup. S. racovitzai occurs in Corsica, Sardinia and in the fossil islands of the Tuscan Archipelago, while S. virei is a polytypic species widely distributed in the central France and Pyrenean area. This vicariant distribution is believed to be the result of the disjunction of the Sardinia-Corsica microplate from …

Les Deux Faces De La Pensée De E. A. Martel, Jacques Choppy

International Journal of Speleology

Réunion de textes de Martel: 1 - Extraits du Nouveau Traité des Eaux Souterraines (1921), donnant l’essentiel de la pensée de l’auteur sur l’hydraulique et la morphologie du karst. 2 - En opposition à cette vision, rappelée de nombreuses fois par l’auteur, extraits de diverses publications (de 1894 à 1930), admettant qu’un fonctionnement en régime noyé était possible: Martel est donc l’un des tout premiers ayant observé des formes de creusement en régime noyé, et les ayant interprétées comme telles.

The Significance Of E. A. Martel For Speleology In Slovenia, Andrej Kranjc

International Journal of Speleology

Three times Martel visited karst in Carniola: in 1879, 1893 and 1896. The importance of his visits and later publications lies in fact that he informed the francophone public about our karst and caves; his visit stimulated the introduction of new technical means into the then Austrian speleology (folding boat, portable telephone); in 1893 due to his researches Postojnska jama became the longest cave in Europe; public found out about existence of caving society Anthron, which was the first Slovene and Slav society of the kind; he set up the foundations of international speleological co-operation and included into it Austrian …

Martel's Voyage To Russia In 1903, Arrigo A. Cigna

International Journal of Speleology

The news concerning caves and karst reported in a Martel’s book on his voyage to Russia in 1903 are here listed and the cave maps are reproduced.

Edouard-Alfred Martel Et Les Cavernes De La Belgique, Daniel André

International Journal of Speleology

An exhaustive report on the activity of Martel in Belgium is here given. In particular some relevant passages of Martel’s letters and papers are also included.

Characteristics Of Street Sweepings In Florida Cities, Robert Brinkmann, Jeffrey G. Ryan, Mark Billus

Geology Faculty Publications

No abstract provided.

A Simple Scenario For Stygobitization In Stenobermuda Schultz, 1978 (Isopoda Asellota Stenetriidae), With Description Of A New Species From Andros Island, Bahamas, Lazare Botosaneanu, Thomas M. Iliffe

International Journal of Speleology

Description of a new stygobitic and troglomorphic species of Stenobermuda from a Blue Hole in the Bahamas, is an opportunity for speculation about hypogean colonization by this and by another cave-dwelling species from Bermuda, starting from populations of a widely distributed Western Atlantic shallow water marine species.

Long Term Stability Of A Terrestrial Cave Community, Claudio Di Russo, Gianmaria Carchini, Mauro Rampini, Marco Lucarelli, Valerio Sbordoni

International Journal of Speleology

We report data on the spatial structure and seasonal variation of the community of Valmarino cave, a medium sized sandstone cave, located a few kilometres from the coast line, in Central Italy. Due to both its habitat features and its relatively recent geological history, Valmarino cave is only inhabited by terrestrial, troglophilic elements, i.e facultative cave dwellers. By means of monthly censuses and density plot estimates we have investigated species abundance, diversity and their spatial organization, by considering separately samples from different cave sectors. Homogeneous sampling design allowed to compare series of samplings performed in 1974 and 1994. On the …

Geographic Variation And Genetic Relationships In Populations Of The Androniscus Dentiger Complex From Central Italy (Isopoda, Oniscidea, Trichoniscidae), Gabriele Gentile, Giuliana Allegrucci

International Journal of Speleology

Androniscus dentiger is a terrestrial isopod distributed from Great Britain to North Africa, inhabiting humid edafic environments, superficial underground compartments and both natural and artificial caves. In this study allozyme data have been used to investigate the geographic variation and the genetic relationships of several populations of A. dentiger from Central Italy, using as outgroups populations from four congeneric species, A. calcivagus, A. cfr. subterraneus, A. spelaeorum, and A. degener. Multivariate analysis of A. dentiger allele frequencies indicates the existence of a group of populations (group A) distributed in a wide geographic area which are genetically …

Martel's Links With Usa, Trevor R. Shaw

International Journal of Speleology

Of the 29% foreign members in the Société de Spéléologie, five lived in the USA. They were Luella Owen (the only woman member of the Société), R. Ellsworth Cali, H.C. Hovey, E Van Epps and C. R. Blackall. E.S. Balch, though not a member, also knew Martel. These members, between them, published ten papers in Spelunca, which also reviewed their other work. The activities of these six, and their links with France, are discussed. Martel actively encouraged cave work in America, as elsewhere, and Hovey, who had been with him during the survey of Aven Armand, he knew quite well. …

Timing Of Basaltic Volcanism Along The Mesa Butte Fault In The San Francisco Volcanic Field, Arizona, From 40Ar/39Ar Dates: Implications For Longevity Of Cinder Cone Alignments, F. M. Conway, David A. Ferrill, Chris M. Hall, Alan P. Morris, John A. Stamatakos, Charles B. Connor, Alex N. Halliday, Christopher Condit

School of Geosciences Faculty and Staff Publications

Using high‐precision stepwise‐heating 40Ar/39Ar methods, we dated volcanic products of at least 12 vents cropping out along the northern segment of the Mesa Butte Fault in the San Francisco Volcanic Field, Arizona, where the relationship between fault and vent alignment is unambiguous. The 40Ar/39Ar isochron dates indicate that the Mesa Butte Fault hosted five episodes of volcanism over a 1 million year interval, from 1400 to 300 ka. The first episode occurred 1 km northwest of the trace of the Mesa Butte Fault, whereas the next two episodes were centered near the intersection of the Mesa Butte and Cedar Ranch …

Variations In The Frequency-Magnitude Distribution With Depth In Two Volcanic Areas: Mount St. Helens, Washington, And Mt. Spurr, Alaska, Stefan Wiemer, Stephen R. Mcnutt

School of Geosciences Faculty and Staff Publications

The frequency-magnitude distribution of earthquakes, characterized using the b-value, is examined as a function of space beneath Mount St. Helens (1988–1996), and Mt. Spurr (1991–1995). At Mount St. Helens, two volumes of anomalously high b (b > 1.3) can be observed at depths of 2.6–3.6 km below the crater floor and below 6.4 km. These anomalies coincide with (1) the depth of vesiculation of ascending magma, and (2) the suggested location of a magma chamber at Mount St. Helens. Study of Mt. Spurr reveals an area of high b-value (b ≥ 1.3) at a depth of about 2.3–4.5 …

Observations At Costa Rican Volcano Offer Clues To Causes Of Eruptions, M. Hagerty, S. Y. Schwartz, M. Protti, Timothy H. Dixon, M. Garcés

School of Geosciences Faculty and Staff Publications

Recent measurements of ground deformation at an active volcano show great promise for elucidating the processes that lead to volcanic eruptions. A long-term effort to continuously monitor ground deformation over a very wide bandwidth using state-of-the-art geodetic, seismic, and acoustic instruments at Arenal Volcano in Costa Rica is producing high-quality recordings of harmonic tremor and explosive events and offers an exciting opportunity to explore possible lunar periodicities in volcanic eruptivity.