Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 271-279). Also available for download via the World Wide Web; free to University of Oregon users.

Active lava lakes present a rare opportunity to observe directly the complex processes occurring within a magma body. Situated on Ross Island, Antarctica, the 3794-m-high crater of Erebus volcano has hosted a phonolite lava lake for decades. Previous studies have shown that many of the lake’s characteristics, such as surface velocity, gas flux and gas composition, exhibit a pronounced pulsatory behaviour on a time-scale of ∼10 min. Focusing primarily on the analysis of infra-red (IR) imagery acquired from the crater rim, this dissertation considers how the periodic behaviour of the Erebus lava lake evolves over decadal time periods, how the cyclic fluctuations of the different properties are interrelated and what can be inferred about the mechanisms occurring beneath the surface of the lake from these observations. Creation of new hardware, software and methodologies to facilitate these types of observations is a strong focus of this work. Chapter 1 introduces the nature of active lava lakes, reviews previous studies of Erebus and presents in detail the research objectives that are addressed by the subsequent chapters. In Chapter 2, a new thermal camera system that was developed as part of this study is described. Designed to run autonomously at the crater-rim of Erebus, this system was installed in December 2012 and has enabled, for the first time, extended time-series of images to be acquired. Chapter 3 briefly describes some of the other hardware and software that was developed as part of this study and outlines how it has been utilised for volcano monitoring. In Chapter 4, a dataset of IR images collected between 2004–2011 is used to assess inter-annual variability in the pulsatory behaviour of the surface motion of the Erebus lava lake. The cyclic behaviour is found to be a sustained feature of the lake, and no obvious changes are observed across the time period analysed. Data collected with the camera system described in Chapter 2 are analysed in Chapter 5 and combined with measurements from other instruments to assess the correlation between the cyclic behaviours of different lake properties. Cycles in surface speed, surface elevation, gas flux and gas composition are found to be highly correlated with each other. In Chapter 6, the surface velocities calculated in the preceding chapters are revisited, and the two-dimensional structure of the flow field is analysed. Chapter 7 demonstrates how the motion tracking methodologies developed for studying the Erebus lava lake can be used to improve high time resolution sulphur dioxide flux estimates - a significant challenge faced in the study presented in Chapter 5. Finally, Chapter 8 presents a synthesis of the key findings and conclusions from the preceding chapters.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 222-247). / Microfiche. / xvii, 246 p. ill. (some col.), maps 29 cm

Measurement of lava effusion rates is a key objective for monitoring basaltic eruptions because it helps constrain geophysical models of magma dynamics, conduit geometry, and both deep and shallow volcano processes. During these eruptions, lava frequently travels through a single "master" lava tube. A new method and instrument for continuously monitoring the crosssectional area of lava streams in tubes and estimating the instantaneous effusion rate (IER) is described. The method uses 2 stationary very low frequency (VLF) radio receivers to measure an unperturbed VLF signal and the influence of highly conductive molten lava on that signal. The difference between these signals is a function of the cross-sectional area of molten lava and the IER. Data from a short test of the instrument are described. This methodology represents a breakthrough in the continuous monitoring of IER because it provides higher temporal resolution than competing methods at a fraction of the cost.

<p>The programming languages that describe hardware circuits are important for circuit </p><p>designers to assist them to design and develop the hardware circuits. </p><p> </p><p>In this master’s project, the Lava hardware description language is used to design and </p><p>develop hardware components for a baseband processing API. Lava is a language </p><p>embedded in the general purpose language Haskell. </p><p> </p><p>The function for checking transmission errors in the baseband processing chain, Cyclic </p><p>Redundancy Check (CRC) is implemented in different ways and tested. </p><p>Linear Feedback Shift Registers (LFSRs) circuits for a particular polynomial generator </p><p>are developed, implemented and simulated by using Lava code to calculate the CRC. </p><p> </p><p>A generalized function of CRC is developed as a circuit generator for any given </p><p>polynomial generator. The circuit is tested by automatic test program.</p>

Ninety-five oriented samples were obtained from nine Recent Cascade lava flows in Oregon. Directions and intensities of remanent magnetization were measured on a spinner magnetometer which measures directions of magnetization to within 1.2° s.d. Angle measurements were plotted graphically using an equal area projection. Mean directions and statistics were calculated by digital computer. Samples were demagnetized in alternating magnetic fields while being rotated in a two axis tumbling device. All flow means, except one, calculated from the original magnetization vectors are distinct from the present geomagnetic field direction. A correspondence is found between scatter observed in a flow and the type of outcrop sampled (whether natural or man-made). This is believed to be a consequence of excessive blockiness and aa characteristics of the lavas. Results of demagnetization tests indicate low secondary magnetizations. Stability is indicated by lack of anisotropy, lack of isothermal and chemical remanent magnetizations, low viscous magnetization, and divergence of flow means from the present field direction. Flow mean directions for five dated flows are used to trace the secular variation of the paleomagnetic field back to 3000 B.P. This secular variation curve agrees with data taken in southwestern United States for the same period of time. It has generally been found that Recent mean pole positions are coincident with the geographical pole within the limits of error of the data. This study yielded a mean direction distinct from an axial dipole direction. However, the age span is limited as eight of the nine flows have ages between 300 and 3850 years. / Graduation date: 1968

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 91-96). Also available on the World Wide Web.

The programming languages that describe hardware circuits are important for circuit designers to assist them to design and develop the hardware circuits. In this master’s project, the Lava hardware description language is used to design and develop hardware components for a baseband processing API. Lava is a language embedded in the general purpose language Haskell. The function for checking transmission errors in the baseband processing chain, Cyclic Redundancy Check (CRC) is implemented in different ways and tested. Linear Feedback Shift Registers (LFSRs) circuits for a particular polynomial generator are developed, implemented and simulated by using Lava code to calculate the CRC. A generalized function of CRC is developed as a circuit generator for any given polynomial generator. The circuit is tested by automatic test program.

Paterae (volcano-tectonic depressions) are among the most prominent topographic features on Io. They are unique, yet in some aspects they resemble calderas known and studied on Earth, Mars, and Venus. They have steep walls, flat floors, and arcuate margins, typical of terrestrial and Martian basalt shield calderas. However, they are much larger (2 km - 202 km diameter, mean 42 km 3 km) and typically lack obvious shields. They are often angular in shape or are found adjacent to mountains, suggesting tectonic influences on their formation. A preferential clustering of paterae at the equatorial sub- and anti-jovian regions is likely a surface expression of tidal massaging and convection in the asthenosphere. Paterae adjacent to mountains have a mean diameter 14 km 9 km larger than that for all paterae, which may indicate paterae grow larger in the fractured crust near mountains. Nightside and eclipse observations of Pele Patera by the Cassini and Galileo spacecraft reveal that much of Pele’s visible thermal emission comes from lava fountains within a topographically confined lava body, most likely a lava lake. Multiple filter images provided color temperatures of 1500 80 K from Cassini ISS data, and 1420 100 K from Galileo SSI data. Hotspots found within paterae (79% of all hotspots) exhibit a wide range of thermal behaviors in global eclipse images. Some hotspots are similar to Pele, consistently bright and confined; others, such as Loki, brighten or dim between observations and move to different locations within their patera. A model for patera formation begins with heating and convection within a high-temperature, low-viscosity asthenosphere. Magma rises through the cold, dense lithosphere either as diapirs [for thermal softening of the lithosphere and sufficiently large diapirs (20 km - 40 km diameter, >5 km thickness)] or through dikes. Magma reaches zones of neutral buoyancy and forms magma chambers that feed eruptions. Collapse over high-level chambers results in patera formation, filling of the patera with lava to create a lava lake, or lateral spreading of the magma chamber and subsequent enlargement of the patera by consuming crustal materials.

No description available.