The work in this thesis concentrates on Katla volcano in southern Iceland. This is one of Europe’s most active volcanoes and its history tells us that it poses many threats to society, both locally (Iceland) and on a broader scale (Europe). Its geological setting is complex, where the effects of a melting anomaly in the mantle and a changing rift geometry, perturb the classical setting of volcanism in a rifting setting. The work has focused on two aspects. The first is the varying distribution of physical properties in the subsurface around the volcano. The second is the distribution of microearthquakes around the volcano. The physical properties that we study are the speeds of seismic waves that reflect variations of temperature, composition and fracturing of the rocks. These can, therefore, help us learn about long-term processes in the volcano. The seismicity gives shorter-term information about deformation associated with current processes. I have applied two tomographic techniques to study Katla’s subsurface to a depth of 5-10 km, namely local-earthquake and ambient-noise tomography. The former makes use of the timing of waves generated by local earthquakes to constrain the earthquakes’ locations and the distribution of wave speed. Here I have concentrated on compressional waves or P waves with a typical frequency content around 10 Hz. With the latter, surface waves are extracted from microseismic noise that is generated far away at sea and their timing is measured to constrain their wave-speed distribution, which then is used to map shear-wave velocity variations. This is done at a typical frequency of 0.3 Hz. I find that the volcano contains rocks of higher velocity than its surroundings, that Katla’s caldera is underlain by low velocities at shallow depth that may be explained by hot or partially molten rocks and that beneath the caldera lies a volume of particularly high velocities that may constitute differentiated cumulates. But, I also find that it is not simple to compare results from such different wave types and discuss a number of complications in that regard. In addition to the well-known microearthquake distribution in the caldera region of Katla and to its west, we have discovered two additional areas of microearthquake activity on the volcano’s flanks, south and east of the caldera. These point to current activity and are, therefore, of interest from a hazard point of view. However, it is difficult to pinpoint their underlying process. Speculation about possible interpretation leads me to hydrothermal processes or small pockets of melt ascending due to their buoyancy or locally enhancing fluid pressure, thereby lowering the effective stress.

This research is focus on the analysis of microbial diversity and existance of methanotrophic microbial strains in Wu-Shan-Ding mud volcano areas. The microbial distribution and diversity in soil surrounding the mud volcano were analyzed by polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). The 16S rDNA sequences from PCR-DGGE bands were used to identify the bacterial strains with NCBI gene bank data. The results showed that the microbial diversity in the fresh erupted mud sample varied with other soil samples. The degrees of diversity were propotion to the distance away from the mud volcano. The main bacterial species found in the mud sample are Brevundimonas terrae, Ralstonia solanacearum, Ralstonia taiwanensis, Pseudonocardiaceae bacterium, Ochrobactrum anthropi, Burkholderia phytofirmans, Stenotrophmonas sp., Methylobacterium sp., Cryseobacterium sp., Sphingobacterium sp., Stenotrophomonas sp. MG-3, and Stenotrophomonas sp. EP01. According to documents, all of the above strains are tolerant to high salt and alkaline. The Ochrobactrum anthropi and Burkholderia phytofirmans were found only in the fresh erupted mud sample and the 5-meter soil sample, while Ralstonia mannitolilytica, Ralstonia pickettii, Amycolatopsis rugosa, and Maricaulis sp. were found only in 10-meter soil sample. In other word, all of the soil samples we examed in this study have their own specified bacterial strains. Two methanotrophic microganisms, Methylobacterium organophilum and Ochrobactrum anthropi were also successfully isolated in pure cultures. The biochemical characteristics of these two strains had been studied. These two strains show a potential might be able to use in the bioremediation of petroleum pollution.

abstract: Tempe Terra, Mars, has a complex history marked by volcanism and tectonism. Investigation results presented here build on previous work to better determine the volcanic history of the Tempe volcanic province by identifying and mapping previously undetected vents, characterizing all vents, identifying spatial and temporal trends in eruptive styles, comparing vent density to similar provinces such as the Snake River Plains of Idaho and Syria Planum and determining absolute age relationships among the volcanic features. Crater size-frequency distribution model ages of 120 Ma to 2.4 Ga indicate the province has been active for over half of the planet's history. During that time, age decreases from southwest to northeast, a trend that parallels the dominant orientation of faulting in the region, providing further evidence that volcanic activity in the region is tectonically controlled (or the tectonics is magmatically controlled). Morphological variation with age hints at an evolving magma source (increasing viscosity) or changing eruption conditions (decreasing eruption rate or eruption through thicker lithosphere). / Dissertation/Thesis / M.S. Geological Sciences 2012

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Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves [175]-181. / vii, 181 l illus., map, tables

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Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references. Also available on the World Wide Web.

The British Tertiary Volcanic Province comprises central volcanic complexes with positive gravity and magnetic anomalies, some centres associated with both large volumes of continental flood basalts and regional dyke swarms. The Lundy Island is the southern most expression of Tertiary volcanism and consists of granite intruded by around 200 dykes and associated with positive gravity and magnetic anomalies. The Lundy Dyke Swarm comprises basalt/dolerite and trachyte to rhyolite intrusions within host Tertiary granite (58.7 ± 1.6 Ma) and Devonian sediments. Outcrops of dykes are confined to coastal exposures on Lundy as they are veneered by peat over most of the island. Dykes present paired magnetic anomaly profiles, which allows their trends tobe determined by proton magnetometry. The dykes have a radial disposition superimposed on a ENE-WSW regional trend. Anisotropy of magnetic susceptibility studies indicate that magma for the radial component was emplaced at shallow to moderate inclinations, suggesting a relatively shallow origin near to the western border of Lundy Island. The regional component was emplaced at shallow to sub-horizontalangles, suggesting lateral movement of magma from a possible source 12 km to the northwest. Geochemical signatures indicate that the Lundy Dyke Swarm was transitional between plume-related magmatism and partial melting of the lithospheric mantle, the magma being stored in several small storage bodies at differing depths in the upper continental crust, rather than in one large magma chamber. Basic dykes at Lee Bay (60 ± 0.6 to 63.1 ± 0.7 Ma) pre-date the Lundy Dyke Swarm and were derived from a discrete magma chamber, possibly near to Morte Point. Conversely, other dykes in North Devon (Fremington dyke - 292.4 ± 1.7 Ma; Horse-Shoe Rocks - 339.6 ± 7.4 Ma) are not directly related to Tertiary magmatism, even though the Horse-Shoe Rocks have a Tertiary palaeomagnetic overprint. The Lundy Igneous Complex (comprising granite, dykes and sub-surface basic rocks) is situated close to the intersection of the Variscan Front and the Welsh Caledonides massif where the continental thickness is between 25 and 27 km. Emplacement of magma was assisted by the heavily fractured nature of the host sediments. However, a large positive gravity anomaly to the northwest of Lundy Island does not have a corresponding magnetic anomaly and so is interpreted as the response to relatively dense uplifted basement in the Lundy Horst rather than a large volume of basic rocks. Thus, the Lundy Igneous Complex probably did not produce sub-aerial volcanic activity, as pressure in the magma chamber would not have exceeded the overlying litho static load, despite the fractured nature of the host rocks.

Using joint P-wave seismic tomography, receiver functions, and ambient noise we image the magmatic structure beneath Newberry Volcano, located near Bend, Oregon. Use of active source and teleseismic events in a joint tomographic inversion provides the ray crossings necessary to resolve a low velocity body around 4 km depth. Receiver functions show large lateral heterogeneity and are consistent with the location of a low velocity body derived from the tomography but require a larger low velocity anomaly. Ambient noise autocorrelations are used to image a low velocity reflector, located at ~3 km depth, shallower than the imaged low velocity body recovered using tomography and receiver functions. Ultimately, our results reveal a magma chamber at 3-4 km depth beneath Newberry caldera, with an overlying partially molten sill at ~3 km depth. These results show the usefulness of dense seismometer deployments over volcanoes.

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