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Shear-Wave Velocities and Derivative Mapping For the Upper Mississippi EmbaymentVance, David M. 01 January 2006 (has links)
During the past two decades, University of Kentucky researchers have been acquiring seismic refraction/reflection data, as well as seismic downhole data, for characterizing the seismic velocity models of the soil/sediment overburden in the central United States. The dataset includes densely spaced measurements for urban microzonation studies and coarsely spaced measurements for regional assessments. The 519 measurements and their derivative products often were not in an organized electronic form, however, limiting their accessibility for use by other researchers. In order to make these data more accessible, this project constructed a database using the ArcGIS 9.1 software. The data have been formatted and integrated into a system serving a wider array of users. The seismic shear-wave velocity models collected at various locations are archived with corresponding x-, y-, and z-coordinate information. Flexibility has been included to allow input of additional data in the future (e.g., seismograms, strong ground-motion parameters and time histories, weak-motion waveform data, etc.). Using the completed database, maps of the region showing derivative dynamic site period (DSP) and weighted shear-wave velocity of the upper 30 m of soil (V30) were created using the ArcGIS 9.1 Geostatistical Analyst extension for examination of the distribution of pertinent dynamic properties for seismic hazard assessments. Both geostatistical and deterministic techniques were employed. Interpolation of V30 data yielded inaccurate predictions because of the high lateral variation in soil layer lithology in the Jackson Purchase Region. As a result of the relatively uniform distribution of depths to bedrock, the predictions of DSP values suggested a high degree of accuracy.
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An Engineering Geological Investigation of the Seismic Subsoil Classes in the Central Wellington Commercial Area.Semmens, Stephen Bradley January 2010 (has links)
The city of Wellington has a high population concentration and lies within a geologically active landscape at the southern end of the North Island, New Zealand. Wellington has a high seismic risk due to its close proximity to several major fault systems, with the active Wellington Fault located in the north-western central city. Varying soil depth and properties in combination with the close proximity of active faults mean that in a large earthquake rupture event, ground shaking amplification is expected to occur in Thorndon, Te Aro and around the waterfront.
This thesis focuses on the area bounded by Thorndon Overbridge in the north, Wellington Hospital in the south, Kelburn in the west, and Oriental Bay in the east. It includes many of the major buildings and infrastructural elements located within the central Wellington commercial area. The main objectives were to create an electronic database which allows for convenient access to all available data within the study area, to create a 3D geological model based upon this data, and to define areas of different seismic subsoil class and depth to rock within the study area at a scale that is useful for preliminary geotechnical analysis (1:5,000.
Borelogs from 1025 holes with accompanying geological and geotechnical data obtained from GNS Science and Tonkin & Taylor were compiled into a database, together with the results from SPAC microtremor testing at 12 sites undertaken specifically for this study. This thesis discusses relevant background work and defines the local Wellington geology.
A 3D geological model of the central Wellington commercial area, along with ten ArcGIS maps including surficial, depth to bedrock, site period, Vs30, ground shaking amplification hazard and site class (NZS 1170.5:2004) maps were created. These outputs show that a significant ground shaking amplification risk is posed on the city, with the waterfront, Te Aro and Thorndon areas most at risk.
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