Thesis (Ph.D.)--Rensselaer Polytechnic Institute, 1996. / Adviser: Ahmed-W. Elgamal. Includes bibliographical references.

Thesis (Ph. D.)--University of Nevada, Reno, 2005. / "August 2005." Includes bibliographical references. Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm.

Thesis (Ph. D.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 410-414).

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

A study was undertaken to evaluate an automated process to invert for seismic moment tensors from seismic data recorded in mining environments. The data for this study was recorded at Nickel Rim South mine, Sudbury, Ontario. The mine has a seismic monitoring system manufactured by ESG Solutions that performs continuous monitoring of seismicity. On average, approximately 400 seismic events are recorded each day. Currently, data are automatically processed by ESG Solution's software suite during acquisition. The automatic processors pick the P- and/or S-wave arrivals, locate the events and solve for certain source parameters, excluding the seismic moment tensor. In order to solve for the moment tensor, data must be manually processed, which is laborious and therefore seldom performed. This research evaluates an automatic seismic moment tensor inversion method and demonstrates some of the difficulties (through inversions of real and synthetic seismic data) of the inversion process. Results using the method are also compared to the inversion method currently available from ESG Solutions, which requires the manual picking of first-motion polarities for every event. As a result of the extensive synthetic testing of the automatic inversion program, as well as the inversion of real seismic data, it is apparent that there are key parameters requiring greater accuracy in order to increase the reliability of the automation. These parameters include the source time function definition, source location (in turn requiring more accurate and precise knowledge of the earth media), arrival time picks and an attenuation model to account for ray-path dependent filtering of the source time function. In order to improve the automatic method three key pieces of research are needed: (1) studying various location algorithms (and the effects of increasing earth model intricacy) and automatic time picking to improve source location methods, (2) studying how the source time pulse can be accurately extracted from the seismic records, as well as the validity of various source models, and (3) studying how attenuation can be modeled more accurately to account for the filtering of the seismic waves through the earth media (in particular distortion to the source time function). / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-08-17 23:08:32.198

No description available.

Combined analysis of the geomorphic evolution of Greymouth with Multi-channel Analysis of Surface Waves (MASW) provides new insight into the geotechnical implications of reclamation work. The MASW method utilises the frequency dependent velocity (dispersion) of planar Rayleigh waves created by a seismic source as a way of assessing the stiffness of the subsurface material. The surface wave is inverted to calculate a shear wave velocity (Park et al., 1999). Once corrected, these shear-wave (Vs) velocities can be used to obtain a factor of safety for liquefaction susceptibility based on a design earthquake. The primary study site was the township of Greymouth, on the West Coast of New Zealand’s South Island. Greymouth is built on geologically young (Holocene-age) deposits of beach and river sands and gravels, and estuarine and lagoonal silts (Dowrick et al., 2004). Greymouth is also in a tectonically active region, with the high seismic hazard imposed by the Alpine Fault and other nearby faults, along with the age and type of sediment, mean the probability of liquefaction occurring is high particularly for the low-lying areas around the estuary and coastline. Repeated mapping over 150 years shows that the geomorphology of the Greymouth Township has been heavily modified during that timeframe, with both anthropogenic and natural processes developing the land into its current form. Identification of changes in the landscape was based on historical maps for the area and interpreting them to be either anthropogenic or natural changes, such as reclamation work or removal of material through natural events. This study focuses on the effect that anthropogenic and natural geomorphic processes have on the stiffness of subsurface material and its liquefaction susceptibility for three different design earthquake events. Areas of natural ground and areas of reclaimed land, with differing ages, were investigated through the use of the MASW method, allowing an initial estimation of the relationship between landscape modification and liquefaction susceptibility. The susceptibility to liquefaction of these different materials is important to critical infrastructure, such as the St. John Ambulance Building and Greymouth Aerodrome, which must remain functional following an earthquake. Areas of early reclamation at the Greymouth Aerodrome site have factors of safety less than 1 and will liquefy in most plausible earthquake scenarios, although the majority of the runway has a high factor of safety and should resist liquefaction. The land west of the St. John’s building has slightly to moderately positive factors of safety. Other areas have factors of safety that reflect the different geology and reclamation history.

No description available.

Iceland provides a unique opportunity to study the processes that occur along mid- ocean ridges. In 1991, thirty temporary seismic stations were installed at the Hengill volcanic complex to record high-quality digital data from local earthquakes. From these data 449 earthquakes have been located, most of them beneath the geothermal area. A local earthquake tomographic inversion was carried out to determine the three- dimensional V(_p) and V(_p) /V(_s) structure to 6 km depth, using P-wave travel times and S-P times from local earthquakes recorded in 1981 and 1991. The resulting models are smoothly varying and give a low data variance. The V(_p) model is similar to that of a previous tomographic inversion in the area, although the models differ in detail. The main high-V(_p) features of these models are interpreted as solidified intrusions, and underlie extinct volcanic centres. A low V(_p) /V(_s) body (-4%) is detected from 0 to 3 km depth that correlates with the surface expression of the geothermal field and is probably due to a combination of effects that include a slightly lower pore fluid pressure (and thus a higher steam content), and rock matrix alteration. Well-constrained moment tensors were determined for 70 local earthquakes by inverting the polarities and amplitude ratios of P and S arrivals. This method works well and is relatively insensitive to wave-speed model and attenuation variations. Most of the earthquakes are non-double-couple with explosive volumetric components. Only 17 (28%) of the earthquakes are consistent with a double-couple model. The remaining earthquakes are modelled as a combination of an opening tensile crack and a shear fault. Two geometries are considered: (1) rupture on two separate fault planes aligned at 45º, and (2) opening-shear rupture on a single fault plane, which is equivalent to coplanar tensile and shear faults. Both models can give the same moment tensors, and the data cannot distinguish between them. They give a good fit to the data, with few polarity misfits for most of the earthquakes. Right-lateral opening-shear strike-slip faulting on near-vertical planes is consistent with the regional seismicity of the South Iceland Seismic Zone. The non-double-couple earthquakes may result from the regional stress regime interacting with the geothermal field.

Thesis (M.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains viii, 58 p. : maps. Includes bibliographical references.