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Articles 211 - 240 of 355
Full-Text Articles in Earth Sciences
Evidence For Reactive Reduced Phosphorus Species In The Early Archean Ocean, Matthew A. Pasek, Jelte P. Hammeijer, Roger Buick, Maheen Gull, Zachary D. Atlas
Evidence For Reactive Reduced Phosphorus Species In The Early Archean Ocean, Matthew A. Pasek, Jelte P. Hammeijer, Roger Buick, Maheen Gull, Zachary D. Atlas
School of Geosciences Faculty and Staff Publications
It has been hypothesized that before the emergence of modern DNA–RNA–protein life, biology evolved from an “RNA world.” However, synthesizing RNA and other organophosphates under plausible early Earth conditions has proved difficult, with the incorporation of phosphorus (P) causing a particular problem because phosphate, where most environmental P resides, is relatively insoluble and unreactive. Recently, it has been proposed that during the Hadean–Archean heavy bombardment by extraterrestrial impactors, meteorites would have provided reactive P in the form of the iron–nickel phosphide mineral schreibersite. This reacts in water, releasing soluble and reactive reduced P species, such as phosphite, that could then …
Annual Variation Of Coastal Uplift In Greenland As An Indicator Of Variable And Accelerating Ice Mass Loss, Qian Yang, Shimon Wdowinski, Timothy H. Dixon
Annual Variation Of Coastal Uplift In Greenland As An Indicator Of Variable And Accelerating Ice Mass Loss, Qian Yang, Shimon Wdowinski, Timothy H. Dixon
School of Geosciences Faculty and Staff Publications
Seasonal melting of the coastal part of the Greenland ice sheet is investigated using GPS vertical displacement data from coastal stations, combined with data on atmospheric and ocean temperatures. Using a high pass filter and cubic spline models, we estimate five variables describing seasonal uplift, a proxy for proximal mass loss, including duration of the melt season and the amount of summer uplift. Our analysis shows both temporal and spatial variations of uplift. Southern coastal Greenland experienced anomalously large uplift in summer 2010, implying significant melting that year. However, the northwest coast did not experience significant change in uplift at …
How Rigid Is A Rigid Plate? Geodetic Constraint From The Trignet Cgps Network, South Africa, Rocco Malservisi, Urs Hugentobler, Richard Wonnacott, Matthias Hackl
How Rigid Is A Rigid Plate? Geodetic Constraint From The Trignet Cgps Network, South Africa, Rocco Malservisi, Urs Hugentobler, Richard Wonnacott, Matthias Hackl
School of Geosciences Faculty and Staff Publications
Rigidity and continuity of the Nubia plate is a fundamental assumption for the kinematic description, the dynamic implications of its interaction with surrounding plates and ultimately an important constraint to the geodynamics processes involved in continental lithospheric rupture. Geophysical, neotectonic and geodynamics considerations suggest the possibility that the Nubia plate is not completely rigid but could be undergoing internal deformation due to the southward propagation of the East African Rift. Here, we utilize the South African TrigNet geodetic network to evaluate the amount of internal deformation within the South African region and the possibility of motion between South Africa and …
Detailed Data Available For Recent Costa Rica Earthquake, Timothy H. Dixon, Susan Schwartz, Marino Protti, Victor Gonzalez, Andrew Newman, Jeff Marshall, Jim Spotila
Detailed Data Available For Recent Costa Rica Earthquake, Timothy H. Dixon, Susan Schwartz, Marino Protti, Victor Gonzalez, Andrew Newman, Jeff Marshall, Jim Spotila
School of Geosciences Faculty and Staff Publications
On 5 September 2012 a magnitude 7.6 earthquake occurred beneath the Nicoya Peninsula of northwestern Costa Rica, rupturing the subduction zone between the Cocos and Caribbean plates. In most subduction zones the locus of seismic slip lies far offshore, making it difficult to infer interface seismogenic processes from on-shore observations. In contrast, the Nicoya Peninsula lies close to the trench (within 70 kilometers), allowing observations directly over the earthquake rupture zone.
Evolution Of Guano Under Different Environmental Conditions: A Mineralogical Approach, Alexandra M. Giurgiu, Bogdan P. Onac, Tudor Tămaș, Joan J. Fornos
Evolution Of Guano Under Different Environmental Conditions: A Mineralogical Approach, Alexandra M. Giurgiu, Bogdan P. Onac, Tudor Tămaș, Joan J. Fornos
School of Geosciences Faculty and Staff Publications
The phosphate minerals from three Romanian caves that host bat guano deposits have been investigated. The XRD and SEM analyses have revealed the presence of seven phosphates (brushite, francoanellite, hydroxylapatite, leucophosphite, taranakite, vashegyite and variscite) along with the more common gypsum, calcite and various allochthonous clay minerals. The occurrence of these phosphate minerals highlights the decomposition and various reactions that take place between the phosphate-rich solutions leaching out from the guano and different cave sediments and/or bedrock. The variation of the environmental conditions in the vicinity and within the guano accumulations is responsible for the type of mineral that is …
Combating Forced Labour And Human Trafficking In Africa: The Role Of Endogenous And Exogenous Forces, Ambe J. Njoh, Elizabeth N.M. Ayuk-Etang
Combating Forced Labour And Human Trafficking In Africa: The Role Of Endogenous And Exogenous Forces, Ambe J. Njoh, Elizabeth N.M. Ayuk-Etang
School of Geosciences Faculty and Staff Publications
It is widely believed that indigenous culture and tradition are at the root of the human trafficking and forced labour problem in Africa. Adherents to this viewpoint also claim that endogenous as opposed to exogenous forces impede efforts to eradicate the problem. This study employed a loglinear regression model to test the tenability of this claim. It hypothesized an inverse association between indigenous culture/tradition and efforts to combat human trafficking. The hypothesis was rejected. It is shown that anti-trafficking initiatives are less successful where indigenous tradition is dominated, or has been usurped, by imported cultural practices.
Probabilistic Approach To Modeling Lava Flow Inundation: A Lava Flow Hazard Assessment For A Nuclear Facility In Armenia, Laura J. Connor, Charles B. Connor, Khachatur Meliksetian, Ivan Savov
Probabilistic Approach To Modeling Lava Flow Inundation: A Lava Flow Hazard Assessment For A Nuclear Facility In Armenia, Laura J. Connor, Charles B. Connor, Khachatur Meliksetian, Ivan Savov
School of Geosciences Faculty and Staff Publications
Probabilistic modeling of lava flow hazard is a two-stage process. The first step is an estimation of the possible locations of future eruptive vents followed by an estimation of probable areas of inundation by lava flows issuing from these vents. We present a methodology using this two-stage approach to estimate lava flow hazard at a nuclear power plant site near Aragats, a Quaternary volcano in Armenia.
Emerging Technology Monitors Ice-Sea Interface At Outlet Glaciers, Timothy H. Dixon, Denis Voytenko, Chad Lembke, Santiago De La Pena, Ian Howat, Noel Gourmelen, Charles Werner, Björn Oddsson
Emerging Technology Monitors Ice-Sea Interface At Outlet Glaciers, Timothy H. Dixon, Denis Voytenko, Chad Lembke, Santiago De La Pena, Ian Howat, Noel Gourmelen, Charles Werner, Björn Oddsson
School of Geosciences Faculty and Staff Publications
Recent melting in Greenland and Antarctica has led to concerns about the long-term stability of these ice sheets and their potential contributions to future sea level rise. Marine-terminating outlet glaciers play a key role in the dynamics of these ice sheets; recent mass losses are likely related to increased influx of warmer water to the base of outlet glaciers, as evidenced by the fact that changes in ocean currents, calving front retreats, glacial thinning, mass redistribution based on satellite gravity data, and accelerating coastal uplift are roughly concurrent [e.g., Holland et al., 2008; Wouters et al., 2008; Jiang …
Evidence For Low-Angle Normal Faulting In The Pumqu-Xianza Rift, Tibet, Patrick W. Monigle, John Nabelek, Jochen Braunmiller, N. Seth Carpenter
Evidence For Low-Angle Normal Faulting In The Pumqu-Xianza Rift, Tibet, Patrick W. Monigle, John Nabelek, Jochen Braunmiller, N. Seth Carpenter
School of Geosciences Faculty and Staff Publications
Low-angle normal faulting is widely discussed as a possible mechanism for continental extension, however, unambiguous evidence for seismogenic low-angle normal faulting is lacking. Here, we investigate seismicity along a short segment of the Pumqu-Xianza Rift (PXR) in southern Tibet, where the HiCLIMB seismic array recorded over 500 earthquakes between 2004 July and 2005 August. Hypocentres of the 40 best recorded earthquakes are approximately 20–25 km west of the rift and tightly clustered at about 10 km depth, consistent with moment tensor depths of the 11 largest (3.4 ≤Mw≤ 4.5) earthquakes. Events in this group have N-S striking …
Active Deformation Near The Nicoya Peninsula, Northwestern Costa Rica, Between 1996 And 2010: Interseismic Megathrust Coupling, Lujia Feng, Andrew V. Newman, Marino Protti, Victor Gonzalez, Yan Jiang, Timothy H. Dixon
Active Deformation Near The Nicoya Peninsula, Northwestern Costa Rica, Between 1996 And 2010: Interseismic Megathrust Coupling, Lujia Feng, Andrew V. Newman, Marino Protti, Victor Gonzalez, Yan Jiang, Timothy H. Dixon
School of Geosciences Faculty and Staff Publications
We use campaign and continuous GPS measurements at 49 sites between 1996 and 2010 to describe the long-term active deformation in and near the Nicoya Peninsula, northwestern Costa Rica. The observed deformation reveals partial partitioning of the Cocos-Caribbean oblique convergence into trench-parallel forearc sliver motion and less oblique thrusting on the subduction interface. The northern Costa Rican forearc translates northwestward as a whole ridge block at 11 ± 1 mm/yr relative to the stable Caribbean. The transition from the forearc to the stable Caribbean occurs in a narrow deforming zone of ∼16 km wide. Subduction thrust earthquakes take 2/3 of …
Spectacular Lightning Revealed In 2009 Mount Redoubt Eruption, Sonja A. Behnke, Ronald J. Thomas, Paul R. Krehbiel, Stephen R. Mcnutt
Spectacular Lightning Revealed In 2009 Mount Redoubt Eruption, Sonja A. Behnke, Ronald J. Thomas, Paul R. Krehbiel, Stephen R. Mcnutt
School of Geosciences Faculty and Staff Publications
The explosive eruption of Alaska's Mount Redoubt volcano in March and April 2009 provided a superb opportunity for studying volcanic lightning. The energetic explosions produced powerful volcanic lightning storms, the largest of which rivaled the intensity of the massive supercell thunderstorms that frequent the midwestern Great Plains. Although lightning often has been observed in the plumes of explosive volcanic eruptions, only a handful of detailed studies have delved into the origins of volcanic lightning. Active volcanoes tend to be situated in remote locations, where they are difficult to observe, and often have sudden, unpredicted eruptions. Even when the eruptions are …
Prioritizing Habitat Restoration Goals In The Tampa Bay Watershed, Mark C. Rains, Shawn Landry, Valerie Seidel, Thomas L. Crisman
Prioritizing Habitat Restoration Goals In The Tampa Bay Watershed, Mark C. Rains, Shawn Landry, Valerie Seidel, Thomas L. Crisman
School of Geosciences Faculty and Staff Publications
No abstract provided.
The Importance Of Craniofacial Sutures In Biomechanical Finite Element Models Of The Domestic Pig, Jen A. Bright
The Importance Of Craniofacial Sutures In Biomechanical Finite Element Models Of The Domestic Pig, Jen A. Bright
School of Geosciences Faculty and Staff Publications
Craniofacial sutures are a ubiquitous feature of the vertebrate skull. Previous experimental work has shown that bone strain magnitudes and orientations often vary when moving from one bone to another, across a craniofacial suture. This has led to the hypothesis that craniofacial sutures act to modify the strain environment of the skull, possibly as a mode of dissipating high stresses generated during feeding or impact. This study tests the hypothesis that the introduction of craniofacial sutures into finite element (FE) models of a modern domestic pig skull would improve model accuracy compared to a model without sutures. This allowed the …
Crystal Structure Of Graphite Under Room-Temperature Compression And Decompression, Yuejian Wang, Joseph E. Panzik, Boris Kiefer, Kanani K. M. Lee
Crystal Structure Of Graphite Under Room-Temperature Compression And Decompression, Yuejian Wang, Joseph E. Panzik, Boris Kiefer, Kanani K. M. Lee
School of Geosciences Faculty and Staff Publications
Recently, sophisticated theoretical computational studies have proposed several new crystal structures of carbon (e.g., bct-C4, H-, M-, R-, S-, W-, and Z-carbon). However, until now, there lacked experimental evidence to verify the predicted high-pressure structures for cold-compressed elemental carbon at least up to 50 GPa. Here we present direct experimental evidence that this enigmatic high-pressure structure is currently only consistent with M-carbon, one of the proposed carbon structures. Furthermore, we show that this phase transition is extremely sluggish, which led to the observed broad x-ray diffraction peaks in previous studies and hindered the proper identification of the post-graphite phase in …
Estimation Of Velocity Uncertainties From Gps Time Series: Examples From The Analysis Of The South African Trignet Network, Matthias Hackl, Rocco Malservisi, Urs Hugentobler, Richard Wonnacott
Estimation Of Velocity Uncertainties From Gps Time Series: Examples From The Analysis Of The South African Trignet Network, Matthias Hackl, Rocco Malservisi, Urs Hugentobler, Richard Wonnacott
School of Geosciences Faculty and Staff Publications
We present a method to derive velocity uncertainties from GPS position time series that are affected by time‐correlated noise. This method is based on the Allan variance, which is widely used in the estimation of oscillator stability and requires neither spectral analysis nor maximum likelihood estimation (MLE). The Allan variance of the rate (AVR) is calculated in the time domain and hence is not too sensitive to gaps in the time series. We derived analytical expressions of the AVR for different kinds of noises like power law noise, white noise, flicker noise, and random walk and found an expression for …
Urban Development, Power Relations, And Water Redistribution As Drivers Of Wetland Change In The Tampa Bay Region Socioecosystem, David B. Lewis, Fenda Akiwumi, Shawn Landry, Rebecca K. Zarger, Mark C. Rains, Susan S. Bell, Thomas L. Crisman, Carl C. Trettin, Kenneth A. Nilsson, Cornelius O. Adjei, Sharon J. Feit, Gina M. Larsen, Ralph B. Perkerson, Paul E. Thurman
Urban Development, Power Relations, And Water Redistribution As Drivers Of Wetland Change In The Tampa Bay Region Socioecosystem, David B. Lewis, Fenda Akiwumi, Shawn Landry, Rebecca K. Zarger, Mark C. Rains, Susan S. Bell, Thomas L. Crisman, Carl C. Trettin, Kenneth A. Nilsson, Cornelius O. Adjei, Sharon J. Feit, Gina M. Larsen, Ralph B. Perkerson, Paul E. Thurman
School of Geosciences Faculty and Staff Publications
No abstract provided.
Evidence Of Atmospheric Gravity Waves During The 2008 Eruption Of Okmok Volcano From Seismic And Remote Sensing Observations, S. De Angelis, Stephen R. Mcnutt, P. W. Webley
Evidence Of Atmospheric Gravity Waves During The 2008 Eruption Of Okmok Volcano From Seismic And Remote Sensing Observations, S. De Angelis, Stephen R. Mcnutt, P. W. Webley
School of Geosciences Faculty and Staff Publications
Okmok volcano erupted on July 12, 2008, following an 11-year hiatus. Detailed inspection of the syn-eruptive seismograms revealed the presence of an ultra long-period mode at a frequency of 1.7 mHz, which is not a characteristic of the background seismic noise at Okmok. Data collected by the National Oceanic and Atmospheric Administration Geostationary Operational Environmental Satellite (GOES) and National Aeronautical and Space Administration Moderate Resolution Imaging Spectroradiometer (MODIS) sensors displayed the propagation of a vigorous ash-and-steam plume up to about 17 km above sea level. We suggest that the observed ultra long-period signals represent the response of the seismometer to …
A Tremor And Slip Event On The Cocos‐Caribbean Subduction Zone As Measured By A Global Positioning System (Gps) And Seismic Network On The Nicoya Peninsula, Costa Rica, Kimberly Outerbridge, Timothy H. Dixon, Susan Y. Schwartz, Jacob I. Walter, Marino Protti, Victor Gonzalez, J. Biggs, Martin Thorwart, Wolfgang Rabbel
A Tremor And Slip Event On The Cocos‐Caribbean Subduction Zone As Measured By A Global Positioning System (Gps) And Seismic Network On The Nicoya Peninsula, Costa Rica, Kimberly Outerbridge, Timothy H. Dixon, Susan Y. Schwartz, Jacob I. Walter, Marino Protti, Victor Gonzalez, J. Biggs, Martin Thorwart, Wolfgang Rabbel
School of Geosciences Faculty and Staff Publications
In May 2007 a network of global positioning systems (GPS) and seismic stations on the Nicoya Peninsula, of northern Costa Rica, recorded a slow-slip event accompanied by seismic tremor. The close proximity of the Nicoya Peninsula to the seismogenic part of the Cocos-Caribbean subduction plate boundary makes it a good location to study such events. Several centimeters of southwest motion were recorded by the GPS stations over a period of several days to several weeks, and the seismic stations recorded three distinct episodes of tremor during the same time span. Inversion of the surface displacement data for the depth and …
Ground Surface Deformation Patterns, Magma Supply, And Magma Storage At Okmok Volcano, Alaska, From Insar Analysis: 1. Inter-Eruption Deformation, 1997-2008, Zhong Lu, Daniel Dzurisin, Juliet Biggs, Charles Wicks Jr., Stephen R. Mcnutt
Ground Surface Deformation Patterns, Magma Supply, And Magma Storage At Okmok Volcano, Alaska, From Insar Analysis: 1. Inter-Eruption Deformation, 1997-2008, Zhong Lu, Daniel Dzurisin, Juliet Biggs, Charles Wicks Jr., Stephen R. Mcnutt
School of Geosciences Faculty and Staff Publications
Starting soon after the 1997 eruption at Okmok volcano and continuing until the start of the 2008 eruption, magma accumulated in a storage zone centered ∼3.5 km beneath the caldera floor at a rate that varied with time. A Mogi-type point pressure source or finite sphere with a radius of 1 km provides an adequate fit to the deformation field portrayed in time-sequential interferometric synthetic aperture radar images. From the end of the 1997 eruption through summer 2004, magma storage increased by 3.2–4.5 × 107 m3, which corresponds to 75–85% of the magma volume erupted in 1997. …
Green Local Governments In Florida: Assessment Of Sustainability Performance, Naimish Upadhyay, Robert Brinkmann
Green Local Governments In Florida: Assessment Of Sustainability Performance, Naimish Upadhyay, Robert Brinkmann
School of Geosciences Faculty and Staff Publications
The sustainability performance of local governments that adopted the Florida Green Building Coalition’s Green Local Government standard was evaluated using a web-based review and survey of 26 local governments within the context of the Three Es of environment, equity, and economic development. The results indicate that while many local governments exhibit a broad commitment to sustainability as evidenced by the inclusion of sustainability in formal documents, such efforts are not present across all government functions or departments. In addition, while local issues are often addressed, interrelated sustainability goals of equity and economic development are not clearly articulated. Most local governments …
Mined-Over Matter, Judy Mcilrath
Mined-Over Matter, Judy Mcilrath
School of Geosciences Faculty and Staff Publications
No abstract provided.
Glacier (?) National Park, Judy Mcilrath
Glacier (?) National Park, Judy Mcilrath
School of Geosciences Faculty and Staff Publications
In this Spreadsheets Across the Curriculum activity, students examine data pertaining to the disappearing glaciers in Glacier National Park. After calculating percentage change of the number of glaciers from 1850 (150) to 1968 (50) and 2009 (26), they move on to the main glacier-monitoring content of the module--area vs. time data for the Grinnell Glacier, one of 26 glaciers that remain in the park. Using a second-order polynomial (quadratic function) fitted to the data, they extrapolate to estimate when there will be no Grinnell Glacier remaining (illustrating the relevance of the question mark in the title of the module). Introductory …
Getting To The Point: Exploring Tectonic Motion At Point Reyes National Seashore, Judy Mcilrath
Getting To The Point: Exploring Tectonic Motion At Point Reyes National Seashore, Judy Mcilrath
School of Geosciences Faculty and Staff Publications
This Spreadsheets Across the Curriculum activity introduces Geology of National Parks students to the geology of the San Andreas Fault, which borders the east side of Point Reyes National Seashore. Photos in the module show the right-lateral displacement along the fault from the 1906 San Francisco earthquake, differences in vegetation and types of rocks on opposite sides of the fault, and the geomorphic expression of the fault (e.g., Tomales Bay). Students get an opportunity to determine distances by measuring map lengths, using the map scales, and converting units. Students also calculate the rate of relative motion of the Pacific Plate …
Yellowstone! A National Park On A Hot Spot, Judy Mcilrath
Yellowstone! A National Park On A Hot Spot, Judy Mcilrath
School of Geosciences Faculty and Staff Publications
This Spreadsheets Across the Curriculum activity introduces Geology of National Parks students to Yellowstone National Park. The module takes a broad overview of volcanic features of the park, including the line of calderas along the up-drift hot spot trace, the mapped area of tuffs produced by their cataclysmic eruptions, and the hydrothermal features for which the park is so well known. Students calculate the rate that the North American Plate has been moving over the hot spot, the relative volume of the materials produced in the cataclysmic eruptions, their recurrence interval, and probability of eruption in any given year. The …
Stratovolcano Growth By Co-Eruptive Intrusion: The 2008 Eruption Of Tungurahua Ecuador, J. Biggs, P. Mothes, M. Ruiz, F. Amelung, Timothy H. Dixon, S. Baker, S-H. Hong
Stratovolcano Growth By Co-Eruptive Intrusion: The 2008 Eruption Of Tungurahua Ecuador, J. Biggs, P. Mothes, M. Ruiz, F. Amelung, Timothy H. Dixon, S. Baker, S-H. Hong
School of Geosciences Faculty and Staff Publications
Volcanic edifices are constructed by a combination of erupted material and internal growth. We use the L-band satellite ALOS to produce InSAR measurements at Tungurahua Volcano, Ecuador. We find a maximum of 17.5 cm of uplift on the upper western flank between December 2007 and March 2008, coincident with an eruption in February 2008. The deformation can be modeled using an ellipsoidal or sill-like source within the edifice. The models require an elongated aspect ratio with a length of 4–6 km. The intruded volume of 1.2 × 106 m3 is roughly equivalent to the bulk erupted volume of …
Measurements And Predictions Of Subsidence Induced By Soil Consolidation Using Persistent Scatterer Insar And A Hyperbolic Model, Sang-Wan Kim, Shimon Wdowinski, Timothy H. Dixon, Falk Amelung, Jeong W. Kim, Joong-Sun Won
Measurements And Predictions Of Subsidence Induced By Soil Consolidation Using Persistent Scatterer Insar And A Hyperbolic Model, Sang-Wan Kim, Shimon Wdowinski, Timothy H. Dixon, Falk Amelung, Jeong W. Kim, Joong-Sun Won
School of Geosciences Faculty and Staff Publications
A space-borne SAR interferometric technique is presented for measuring and predicting ground subsidence associated with soil consolidation. Instead of a conventional constant velocity model, a hyperbolic model is introduced for persistent scatterer SAR interferometry (PSI) processing. Twenty three JERS-1 SAR acquired between 1992 and 1998 were used to measure land subsidence in Mokpo city, Korea which had been primarily built on land reclaimed from the sea. Two subsidence field maps were derived and compared: a constant velocity model and a hyperbolic model. Non-linear components depending on the stage of soil consolidation are well represented by the hyperbolic model. The maximum …
Stability Of The Rotation Axis In High‐Resolution Mantle Circulation Models: Weak Polar Wander Despite Strong Core Heating, K. Schaber, H. -P. Bunge, B. S. A. Schuberth, Rocco Malservisi, A. Horbach
Stability Of The Rotation Axis In High‐Resolution Mantle Circulation Models: Weak Polar Wander Despite Strong Core Heating, K. Schaber, H. -P. Bunge, B. S. A. Schuberth, Rocco Malservisi, A. Horbach
School of Geosciences Faculty and Staff Publications
Growing evidence points to a substantial heat flow across the core‐mantle boundary (CMB), but the rotational stability of strongly bottom heated mantle flow with prominent upwelling plumes is poorly known. Here we calculate polar motion for the past 100 Myr induced in a new class of isochemical high‐resolution mantle circulation models (MCMs) with Earth‐like convective vigor and up to 12 TW core heat flux. Our MCMs include internal heating and a simple three‐layer viscosity profile associated with the lithosphere (1023 Pa s) and the upper (1021 Pa s) and the lower mantle (1023 Pa s), separated at 100 and 650 …
Strain Rate Patterns From Dense Gps Networks, Matthias Hackl, Rocco Malservisi, Shimon Wdowinski
Strain Rate Patterns From Dense Gps Networks, Matthias Hackl, Rocco Malservisi, Shimon Wdowinski
School of Geosciences Faculty and Staff Publications
The knowledge of the crustal strain rate tensor provides a description of geodynamic processes such as fault strain accumulation, which is an important parameter for seismic hazard assessment, as well as anthropogenic deformation. In the past two decades, the number of observations and the accuracy of satellite based geodetic measurements like GPS greatly increased, providing measured values of displacements and velocities of points. Here we present a method to obtain the full continuous strain rate tensor from dense GPS networks. The tensorial analysis provides different aspects of deformation, such as the maximum shear strain rate, including its direction, and the …
Fore-Arc Motion And Cocos Ridge Collision In Central America, Peter Lafemina, Timothy Dixon, Rob Govers, Edmundo Norabuena, Henry Turner, Armando Saballos, Glen Mattioli, Marino Protti, Wilfried Strauch
Fore-Arc Motion And Cocos Ridge Collision In Central America, Peter Lafemina, Timothy Dixon, Rob Govers, Edmundo Norabuena, Henry Turner, Armando Saballos, Glen Mattioli, Marino Protti, Wilfried Strauch
School of Geosciences Faculty and Staff Publications
We present the first regional surface velocity field for Central America, showing crustal response to interaction of the Cocos and Caribbean plates. Elastic half-space models for interseismic strain accumulation on the dipping subduction plate boundary fit the GPS data well and show strain accumulation offshore and beneath the Nicoya and Osa peninsulas in Costa Rica but not in Nicaragua. Since large subduction zone earthquakes occur in Nicaragua, we suggest that interseismic locking in Nicaragua and some other parts of Central America occurs but is mainly shallow, depth, too far offshore to be detected by our on-land GPS measurements. Our data …
Unusual Anatomy Of The Ectoparasitic Muricid Vitularia Salebrosa (King And Broderip, 1832) (Neogastropoda: Muricidae) From The Pacific Coast Of Panama, Luiz R. L. Simone, Gregory S. Herbert, Didier Merle
Unusual Anatomy Of The Ectoparasitic Muricid Vitularia Salebrosa (King And Broderip, 1832) (Neogastropoda: Muricidae) From The Pacific Coast Of Panama, Luiz R. L. Simone, Gregory S. Herbert, Didier Merle
School of Geosciences Faculty and Staff Publications
The morphology and anatomy of Vitularia salebrosa, a muricid ectoparasitic on other mollusks, are investigated based on study of specimens from western Panama. Distinctive characters of this species include the small size of the buccal mass and radular apparatus, simplification of the odontophore muscles and diminished lateral teeth of the radula; an elongated, narrow proboscis; narrow digestive tract and a differentiable glandular region at the beginning of the posterior esophagus. These traits are consistent with adaptive specialization for an ectoparasitic life history