The double difference earthquake location algorithm, implemented in the program HYPODD, was used to relocate a data set of approximately 1000 earthquakes in the eastern Tennessee seismic zone (ETSZ), using a recently developed velocity model. The double difference algorithm is used to calculate accurate relative hypocenter locations by removing the effects of un-modeled velocity structure. The study examines the earthquake hypocenter relocations in an effort to resolve fault orientations and thereby gain insights into the tectonics of the seismic zone. The analysis involves visual comparison of three-dimensional perspective plots of the hypocenter relocations oriented according to focal mechanism nodal planes derived from events within several, dense clusters of earthquakes. The northwestern boundary of the seismic zone corresponds to the steep magnetic gradient of the New York-Alabama lineament. The double-difference relocations reinforced previous interpretations of a vertical boundary between seismic and relatively aseismic crust at that location. Areas at the northeastern and southwestern ends of the ETSZ exhibit northwest trending hypocenter alignments, which are perpendicular to the overall northeastern trend of the seismic zone. These alignments agree with focal mechanism nodal plane orientations and are interpreted as seismogenic faults. In the central, most seismically active portion of the ETSZ, relocations appear to indicate a diffuse zone of hypocenters that are west-striking and north-dipping. The orientation of this zone of earthquake hypocenters is consistent with an existing seismic reflection profile that images mid to upper crustal reflectors with apparent dips of approximately 35 degrees to the north. The interpreted fault planes are all consistent with an east-northeast oriented, sub-horizontal maximum regional compressive stress, consistent with findings in previous studies. / Master of Science

Expanding the standard, single-well recording geometry used to monitor seismicity during hydro-fracture treatments could provide more accurate hypocenter locations and seismic velocities, improving general reservoir characterization. However, for the real, two-well data set obtained for this project, only S-wave picks were available, and testing resulted in anomalous hypocenter location behavior. This study uses a hypocenter location algorithm and both real and synthetic data sets to investigate how the accuracy of the velocity model, starting hypocenter location, recording geometry, and arrival-time picking error affect final hypocenter locations. Hypocenter locations improved using a velocity model that closely matched the observed sonic log rather than a smoothed version of this model. The starting hypocenter location did not affect the final location solution if both starting and final locations were between the wells. Two solutions were possible when the true solution was not directly between the wells. Adding realistic random picking errors to synthetic data closely modeled the dispersed hypocenter error pattern observed in the real data results. Adding data from a third well to synthetic tests dramatically reduced location error and removed horizontal geometric bias observed in the two-well case. Seismic event data recorded during hydro-fracture treatments could potentially be used for three-dimensional joint hypocenter-velocity tomography. This would require observation wells close enough to earthquakes to record P- and S-wave arrivals or wells at orientations sufficient to properly triangulate hypocenter locations. Simulating results with synthetic tests before drilling could optimize survey design to collect data more effectively and make analysis more useful. / Master of Science

The North Anatolian Fault (NAF) is one of the world&rsquo / s largest active continental strikeslip faults, and forms the northern margin of the Anatolian plate. Although its geologic and geomorphologic features are well defined, crustal deformation and associated seismicity around central segment of the NAF is relatively less-known. In this study, we analyzed locations and focal mechanisms of 172 events with magnitude &ge / 3, which are recorded by 39 broadband seismic stations deployed by the North Anatolian Passive Seismic Experiment (2005-2008). Distribution of the events shows that the local seismicity in the area is widely distributed, suggesting a widespread continental deformation, particularly in the southern block. For the entire data set, P- and S- arrival times are picked and events are relocated using the HYPOCENTER program. Then, relocated events which have a good azimuthal coverage with a maximum gap of 120&deg / and at least 13 P- wave readings are selected and 1-D inversion algorithm, VELEST, is used to derive the 1-D seismic velocity model of the region. The final model with updated locations is later put together to the FOCMEC program, to obtain focal mechanisms solutions. In this step, an iterative scheme is applied by increasing the number of data errors. To obtain more unique solutions, first motions of P and SH v phases are used along with SH/P amplitude ratios. Resultant 109 well-constrained focal mechanisms later used to perform stress tensor inversion across the region. Our focal mechanisms suggest a dominant strike-slip deformation along two major fault sets in the region. In the east, E-W trending splays (Ezinepazari, Almus, and La&ccedil / in Kizilirmak) show right-lateral strike-slip motion similar to the NAF whereas in the west, N-S trending faults (Dodurga, Eldivan) show left lateral strike-slip motion. Overall, stress orientations are found as: maximum principal stress, &sigma / 1, is found to be subhorizontal striking NW-SE, the intermediate principle stress, &sigma / 2, is vertically orientated and the minimum principal stress, &sigma / 3, is found to be NE &ndash / SW striking, consistent with the strike-slip regime of the region.

Using data from the frequency disturbance recorders (FDRs) that comprise the nation-wide frequency monitoring network known as FNET, disturbances in the eastern interconnected system (EI) have been monitored and recorded over the past several years. Analysis of this and other data by a wide variety of research scientists and engineers has rendered the idea that frequency disturbances from generator trips, transmission line trips, load trips, and other events, travel with finite speed as electromechanical waves throughout any power system (in this case the EI). Using FNET data as a tool, it is possible to measure and output the arrival times of these disturbance waves with a time resolution of 100 ms. To observe with certainty the arrival time of the frequency disturbance waves, field data collected by the FDRs must first be conditioned in a robust manner. The current method that uses the moving mean of raw FDR data is analyzed and two computationally efficient robust methods are suggested in this report. These new methods that rely on robust statistics are more resistant to the effect of outliers contained within the raw FDR data. Furthermore, like the moving mean, these methods smooth the raw data without removing the general trend. Having recorded and conditioned the FDR data, three conventional triangulation techniques taken from the field of seismology are proposed and analyzed. This study reconfirms the fact that the EI is not a medium of continuous elasticity though which the frequency perturbations travel but rather a discontinuous patchwork of varying elasticities. Within this report, nine generator trip events are analyzed and the aforementioned triangulation methods are applied. The advantages and disadvantages of each method are discussed. To conclude, axioms of future research are proposed and delineated. / Master of Science

Made available in DSpace on 2015-03-13T17:08:29Z (GMT). No. of bitstreams: 1 PauloHSO_DISSERT.pdf: 5075082 bytes, checksum: 87acfa3f71ca9cabf5ba6b9a46a86972 (MD5) Previous issue date: 2010-08-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The town of Sobral is located at the northwest part of the Cear? State, 250 km away from its capital, Fortaleza. In January 2008, an intense seismic activity began near Sobral with one event with magnitude 4,2mb on May 21. Since the start of its seismic activity, all events were recorded by the SBBR station (located on EMBRAPA Caprinos Farm), which operates in the region since August 2007. After this event, monitoring the seismic activity was carried out with the deployment of a local three component digital seismographic network, from June 5, 2008 until September 24. Initially, this network was composed of six seismographic stations. Later additional five stations were deployed until August 26 2008. This local network detected approximately 2,800 earthquakes. In this study we analyzed 581 earthquakes recorded by at least three stations for hypocentral and focal mechanism determination, and to contribute to a better explanation of the seismicity which in this region. To determine the hypocenters, we used a half-space model, with vP = 6,00 km/s and vP/vS = 1,71. From the hypocentral determination, it was revealed an active seismic zone with depth ranging between 1 and 8 km, 6 km long in E - W direction. The determination of fault planes and focal mechanism was obtained using the programs FPFIT and PLAN, which allowed comparison between their respective results in order to obtain more accurate results. A set of 24 earthquakes were selected to determine fault using PLAN planes and focal mechanisms using FPFIT. With the aid of detailed map of hypocenters this set, it was possible to identify three structures. Therefore, the set of 24 earthquakes were divided into three subsets. The type of mechanism was predominantly strike-slip with a dextral direction. Although the region has two tectonic structures near the site of the study area: the Caf?- Ipueiras Fault (normal fault) and the Sobral-Pedro II Lineament (dextral strike-slip fault) it was not possible to correlate the seismicity founded with those structures / A cidade de Sobral est? localizada na por??o Noroeste do estado do Cear?, a 250 km de sua capital, Fortaleza. No in?cio de 2008, uma intensa atividade s?smica iniciou-se nas proximidades de Sobral, ocorrendo no dia 21 de maio, o evento com a maior magnitude registrada na regi?o (4,2 mb). Todos os eventos, desde o in?cio, foram registrados pela esta??o SBBR, localizada na fazenda da EMBRAPA Caprinos, que opera na regi?o desde agosto de 2007. Ap?s o evento de maio de 2008, o monitoramento da sismicidade foi realizado com uma rede sismogr?fica local, com in?cio de opera??o no dia 5 de junho de 2008. Inicialmente, esta rede foi constitu?da de 6 esta??es sismogr?ficas digitais, sendo depois preenchida com mais 5, totalizando 11 esta??es digitais, cada uma com 3 componentes. A rede com at? 11 esta??es sismogr?ficas operou entre o dia 6 de junho e 24 de setembro de 2008, detectando cerca de 2820 sismos, em pelo menos uma esta??o. No presente trabalho foram analisados os 581 sismos registrados, no m?nimo, em tr?s esta??es, objetivando a determina??o de hipocentros, mecanismos focais e contribuir para uma melhor compreens?o da sismicidade ocorrida na regi?o Noroeste do Cear?. Para a determina??o hipocentral, a partir da an?lise dos 581 eventos registrados pela rede, foram obtidos como par?metros do modelo de velocidades, 1,71 para VP/VS e 6.00 km/s para VP, possibilitando encontrar uma zona s?smica ativa com profundidade variando de 1,1 km a 7,8 km e com 6 km de extens?o horizontal na dire??o aproximada E-W. A determina??o dos planos de falha e mecanismos focais foi obtida com o aux?lio dos programas PLAN e FPFIT, possibilitando a utiliza??o dos resultados do primeiro para ajudar a melhor definir o mecanismo focal, obtido com o programa FPFIT. Para obter os par?metros dos planos de falha e mecanismos focais, foi selecionado um conjunto de 24 sismos com melhor precis?o hipocentral. Com estes sismos, foi poss?vel construir um mapa detalhado dos seus hipocentros, visando obter aux?lio na identifica??o do tipo de mecanismo focal. Os mecanismos obtidos foram do tipo transcorrente, com movimento dextral. Apesar de a regi?o possuir duas importantes estruturas tect?nicas pr?ximas ao local da ?rea estudada: a falha Caf?-Ipueiras e o Lineamento Sobral-Pedro II, n?o foi poss?vel obter correla??o entre a sismicidade encontrada e qualquer uma dessas fei??es geol?gicas

At the northern extent of the Cascadia subduction zone, the subducting Explorer and Juan de Fuca plates interact across a translational deformation zone, known as the Nootka fault zone. The Seafloor Earthquake Array Japan-Canada Cascadia Experiment (SeaJade) was designed to study this region. In two parts (SeaJade I and II, deployed from July – September 2010 and January – September 2014), seismic data from the SeaJade project has led to several important discoveries. Hypocenter distributions from SeaJade I and II indicate primary and secondary conjugate faults within the Nootka fault zone. Converted phase analysis and jointly determined seismic tomography with double-difference relocated hypocenters provide evidence to several velocity-contrasting interfaces seaward of the Cascadia subduction front at depths of ~4-6 km, ~6-9 km, ~11-14 km, and ~14-18 km, which have been interpreted as the top of the oceanic crust, upper/lower crust boundary, oceanic Moho, and the base of the highly fractured and seawater/mineral enriched veins within oceanic mantle. During SeaJade II, a MW 6.4 mainshock and subsequent aftershocks, known as the Nootka Sequence, highlighted a previously unidentified fault within the subducted Explorer plate. This fault reflects the geometry of the subducting plate, showing downward bending of the plate toward the northwest. This plate bend can be attributed to negative buoyancy from margin parallel mantle flow induced by intraslab tearing further northwest. Seismic tomography reinforces the conclusions drawn from the Nootka Sequence hypocenter distribution. Earthquakes from the entire SeaJade II catalogue reveal possible rotated paleo-faults, identifying the former extent of the Nootka fault zone from ~3.5 Ma. / Graduate

Classically, wide-area synchronized power system monitoring has been an expensive task requiring significant investment in utility communications infrastructures for the service of relatively few costly sensors. The purpose of this research is to demonstrate the viability of power system monitoring from very low voltage levels (120 V). Challenging the accepted norms in power system monitoring, the document will present the use of inexpensive GPS time synchronized sensors in mass numbers at the distribution level. In the past, such low level monitoring has been overlooked due to a perceived imbalance between the required investment and the usefulness of the resulting deluge of information. However, distribution level monitoring offers several advantages over bulk transmission system monitoring. First, practically everyone with access to electricity also has a measurement port into the electric power system. Second, internet access and GPS availability have become pedestrian commodities providing a communications and synchronization infrastructure for the transmission of low-voltage measurements. Third, these ubiquitous measurement points exist in an interconnected fashion irrespective of utility boundaries. This work offers insight into which parameters are meaningful to monitor at the distribution level and provides applications that add unprecedented value to the data extracted from this level. System models comprising the entire Eastern Interconnection are exploited in conjunction with a bounty of distribution level measurement data for the development of wide-area disturbance detection, classification, analysis, and location routines. The main contributions of this work are fivefold: the introduction of a novel power system disturbance detection algorithm; the development of a power system oscillation damping analysis methodology; the development of several parametric and non-parametric power system disturbance location methods, new methods of power system phenomena visualization, and the proposal and mapping of an online power system event reporting scheme. / Ph. D.