A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, December, 2013. / The Palaeoproterozoic southern Goren volcano-sedimentary belt of northeast Burkina Faso represents a sequence/package of rocks formed in a back-arc basin environment. Evidence is based on a conformable sequence of basalts that have geochemical affinities of normal mid-oceanic ridge style basalts (N-MORB) as well as arc-related magmas. Tholeiitic compositions, determined by major and trace element geochemistry, are exclusive to the study area, which is unique to northeast Burkina Faso. Flat, chondrite-normalised REE patterns suggest dominantly N-MORB compositions, with the occasional elevated Th and Al2O3 values, suggestive of arc basalts. Depleted chondrite-normalised concentrations of phosphorus (0.5-0.03 times lower than chondrite) and Ti (1-5 times chondrite) as well as anomalous concentrations of N-MORB-normalised Ta (80-120 times greater) are characteristic of the tholeiitic basalts of the Goren belt. The volcanic rocks are intercalated with a succession of volcanogenic manganese deposits, siltstone, volcaniclastite, volcanogenic greywacke and a discrete pyroclastic breccia deposit composed of lapilli- to bomb-sized volcanic debris, indicative of bimodal volcanism. The volcanic facies were established through field and petrographic interpretations. The subaqueous facies architecture consists of proximal, coherent and autoclastic basaltic flow units containing porphyritic, aphyric, amygdaloidal and hyaloclastic textures as well as pillowed, jointed and flow-banded basaltic lithofacies. Proximal to distal volcanogenic manganese deposits intercalated with basalt flows indicate a syn-volcanic genesis. A discrete pyroclastic interbed (~300 m thick) within a volcanogenic, marginal marine to offshore greywacke succession occupies a distal facies relative to the volcanic source and indicates a bimodal source of volcanism, i.e., mafic and intermediate. Volcanogenic manganese deposits are characterized by quartz-ankerite stockwork breccia, a braunite-ilmenite-magnetite-chalcopyrite-pyrite-(gold) mineral assemblage and increased Ba concentrations, indicating syn-volcanic seafloor-related hydrothermal activity. The Goren volcano-sedimentary belt presents potential for economic mineralisation in volcanogenic primary manganese and base metal deposits.

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This dissertation investigates the link between volcanic unrest and the occurrence of moderate-to-large earthquakes with a specific type of focal mechanism. Vertical compensated-linear-vector-dipole (vertical-CLVD) earthquakes have vertical pressure or tension axes and seismic radiation patterns that are inconsistent with the double-couple model of slip on a planar fault. Prior to this work, moderate-to-large vertical-CLVD earthquakes were known to be geographically associated with volcanic centers and vertical-CLVD earthquakes were linked to a tsunami in the Izu-Bonin volcanic arc and a subglacial fissure eruption in Iceland. Vertical-CLVD earthquakes are some of the largest and most anomalous earthquakes to occur in volcanic systems, yet their physical mechanisms remain controversial largely due to the small number of observations. Five vertical-CLVD earthquakes with vertical pressure axes are identified near Nyiragongo volcano in the Democratic Republic of the Congo. Three earthquakes occur within days of a fissure eruption at Nyiragongo, and two occur several years later in association with the refilling of the lava lake in the summit crater of the volcano. Detailed study of these events shows that the earthquakes have slower source processes than tectonic earthquakes with similar magnitudes and locations. All five earthquakes are interpreted as resulting from slip on inward-dipping ring-fault structures located above deflating shallow magma chambers. The Nyiragongo study supports the interpretation that vertical-CLVD earthquakes may be causally related to dynamic physical processes occurring inside the edifices or magmatic plumbing systems of active volcanoes. Two seismicity catalogs from the Global Centroid Moment Tensor (CMT) Project are used to search for further examples of shallow earthquakes with robust vertical-CLVD focal mechanisms. CMT solutions for approximately 400 target earthquakes are calculated and 86 vertical-CLVD earthquakes are identified near active volcanoes. Together with the Nyiragongo study, this work increases the number of well-studied vertical-CLVD earthquakes from 14 to 101. Vertical-CLVD earthquakes have focal depths in the upper ~10 km of the Earth's crust, and ~80% have centroid locations within 30 km of an active volcanic center. Vertical-CLVD earthquakes are observed near several different types of volcanoes in a variety of geographic and tectonic settings, but most vertical-CLVD earthquakes are observed near basaltic-to-andesitic stratovolcanoes and submarine volcanoes in subduction zones. Vertical-CLVD earthquakes are linked to tsunamis, volcanic earthquake swarms, effusive and explosive eruptions, and caldera collapse, and approximately 70% are associated with documented volcanic eruptions or episodes of volcanic unrest. Those events with vertical pressure axes typically occur after volcanic eruptions initiate, whereas events with vertical tension axes commonly occur before the start of volcanic unrest. Both types of vertical-CLVD earthquakes have longer source durations than tectonic earthquakes of the same magnitude. The isotropic and pure vertical-CLVD components of the moment tensor cannot be independently resolved using our long-period seismic dataset. As a result, several physical mechanisms can explain the retrieved deviatoric vertical-CLVD moment tensors, including dip-slip motion on ring faults, volume exchange between two reservoirs, the opening and closing of tensile cracks, and volumetric sources. An evaluation of these mechanisms is performed using constraints obtained from detailed studies of individual vertical-CLVD earthquakes. Although no single physical mechanism can explain all of the characteristics of vertical-CLVD earthquakes, a ring-faulting model consisting of slip on inward- or outward-dipping ring faults triggered by the inflation or deflation of a shallow magma chamber can account for their seismic radiation patterns and source durations, as well as their temporal relationships with volcanic unrest. The observation that most vertical-CLVD earthquakes are associated with volcanoes with caldera structures supports this interpretation.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Geological Sciences." Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 235-250).

Thesis (M.Sc. Earth and Ocean Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed February 25, 2008) Includes fold out pages. Includes bibliographical references (p. 153-160)

Thesis (Ph. D.)-- University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution. / Bibliography: p. 336-353.

Inaugural-Dissertation Universitat Zurich. / Based on observations made in Valparaiso by Dr. Heinrich von Dessauer, from Jan. 1, 1872, to Aug. 9, 1879. Verzeichnis der Ausserchilenischen Erdbeben und Vulkanausbruche p. 70-72.

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Michael A. Ivie. Includes bibliographical references (leaves 111-117).