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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

A Grid-based Seismic Hazard Analysis Application

Kocair, Celebi 01 September 2010 (has links) (PDF)
The results of seismic hazard analysis (SHA) play a crucial role in assessing seismic risks and mitigating seismic hazards. SHA calculations generally involve magnitude and distance distribution models, and ground motion prediction models as components. Many alternatives have been proposed for these component models. SHA calculations may be demanding in terms of processing power depending on the models and analysis parameters involved, and especially the size of the site for which the analysis is to be performed. In this thesis, we develop a grid-based SHA application which provides the necessary computational power and enables the investigation of the effects of applying different models. Our application not only includes various already implemented component models but also allows integration of newly developed ones.
32

Development Of A Gis Software For Evaluating Network Relibility Of Lifelines Under Seismic Hazard

Oduncucuoglu, Lutfi 01 December 2010 (has links) (PDF)
Lifelines are vital networks and it is important that those networks are still be functional after major natural disasters such as earthquakes. The goal of this study is to develop a GIS software for evaluating network reliability of lifelines under seismic hazard. In this study, GIS, statistics and facility management is used together and a GIS software module, which constructs GIS based reliability maps of lifeline networks, is developed by using geoTools. Developed GIS module imports seismic hazard and lifeline network layers in GIS formats using geoTools libraries and after creating a gridded network structure it uses a network reliability algorithm, initially developed by Yoo and Deo (1988), to calculate the upper and lower bounds of lifeline network reliability under seismic hazard. Also it can show the results in graphical form and save as shape file format. In order to validate the developed application, results are compared with a former case study of Selcuk (2000) and the results are satisfactorily close to previous study. As a result of this study, an easy to use, GIS based software module that creates GIS based reliability map of lifelines under seismic hazard was developed.
33

Interdependent response of telecommunication and electric power systems to seismic hazard

Leelardcharoen, Kanoknart 25 August 2011 (has links)
Infrastructure systems are essential to the functioning of contemporary societies and economies. A major disruption to the built environment can lead to severe public safety issues and economic losses. Within the past few decades, modern control and information technologies have been rapidly developed in an attempt to improve the reliability of individual utility systems by exchanging technologies across them. One of the major ramifications is the emergence of interdependencies among these critical infrastructure systems, especially when facing major disruptions. Failure of an individual system becomes more likely to affect the functionality of other interconnected infrastructure systems. In order to mitigate such consequences, the mechanics of interdependencies and failure propagation among the systems must be understood. This research focuses on the development of a framework for probabilistically quantifying interdependent responses of two essential infrastructure systems - telecommunication and electric power systems - subjected to seismic hazards, which are one of the most powerful and geographically extensive threats. The study explores the effects of seismic hazards beyond the obvious seismic-induced physical damage to utility system facilities. In particular, the seismic evaluation of telecommunication systems considers the degradation of system performance due to physical damage and the abnormally high usage demands in telecommunication systems expected after catastrophic earthquakes. Specifically, a newly developed seismic-induced congestion model is proposed, and the probabilistic formulations of the critical interdependencies across telecommunication and power systems are presented in a probabilistic framework. The study illustrates the procedure for fragility analysis of interdependent systems and presents a practical application through a test bed implementation in Shelby County, TN. From this study, telecommunication systems are found to be very vulnerable to seismic-induced congestion. The electric power interdependencies amplify the degradation in telecommunication systems up to 50% in their vulnerability while electric power operations are heavily dependent upon telecommunication infrastructures and the fragility median of electric power system observability can decrease by 30%. The study also indicates up to 100% overestimation of the independent fragility analysis and the results reveal the relationship between system topology and the sensitivity of system performance to the intensity of interdependencies. The proposed methodology is expected to be a valuable tool for decision making in evaluating seismic mitigation strategies and also to provide the foundation for future studies on interdependent responses of other critical infrastructures.
34

Morphostructural and paleo-seismic analysis of fault interactions in the Oxford–Cust–Ashley fault system, Canterbury

Mahon, Luke Evan January 2015 (has links)
This study investigates evidence for linkages and fault interactions centred on the Cust Anticline in Northwest Canterbury between Starvation Hill to the southwest and the Ashley and Loburn faults to the northeast. An integrated programme of geologic, geomorphic, paleo-seismic and geophysical analyses was undertaken owing to a lack of surface exposures and difficulty in distinguishing active tectonic features from fluvial and/or aeolian features across the low-relief Canterbury Plains. LiDAR analysis identified surface expression of several previously unrecognised active fault traces across the low-relief aggradation surfaces of the Canterbury Plains. Their presence is consistent with predictions of a fault relay exploiting the structural mesh across the region. This is characterised by interactions of northeast-striking contractional faults and a series of re-activating inherited Late Cretaceous normal faults, the latter now functioning as E–W-striking dextral transpressive faults. LiDAR also allowed for detailed analysis of the surface expression of individual faults and folds across the Cust Anticline contractional restraining bend, which is evolving as a pop-up structure within the newly established dextral shear system that is exploiting the inherited, now re-activated, basement fault zone. Paleo-seismic trenches were located on the crest of the western arm of the Cust Anticline and across a previously unrecognised E–W-striking fault trace, immediately southwest of the steeply plunging Cust Anticline termination. These studies confirmed the location and structural style of north-northeast-striking faults and an E–W-striking fault associated with the development of this structural culmination. A review of available industry seismic reflection lines emphasised the presence of a series of common structural styles having the same underlying structural drivers but with varying degrees of development and expression, both in the seismic profiles and in surface elevations across the study area. Based on LiDAR surface mapping and preliminary re-analysis of industry seismic reflection data, four fault zones are identified across the restraining bend structural culminations, which together form the proposed Oxford–Cust–Ashley Fault System. The 2010–2012 Canterbury Earthquake Sequence showed many similarities to the structural pattern established across the Oxford–Cust–Ashley Fault System, emphasising the importance of identification and characterization of presently hidden fault sources, and the understanding of fault network linkages, in order to improve constraints on earthquake source potential. Improved understanding of potentially-interactive fault sources in Northwest Canterbury, with the potential for combined initial fault rupture and spatial and temporal rupture propagation across this fault system, can be used in probabilistic seismic hazard analysis for the region, which is essential for the suitability and sustainability of future social and economic development.
35

Tectonic Geomorphology and Seismic Hazard of the Mt Fyffe Section of the Hope Fault

Coulter, Roseanne Frances January 2007 (has links)
The northeast-trending transpressive Hope fault is a major tectonic element of the active Pacific-Australian plate boundary zone through New Zealand. This study presents geomorphic and paleoseismic field data from the Mt Fyffe section of the Hope fault, which in turn is used to develop a seismic hazard map for the adjacent area. The Mt Fyffe section is a 12 km long, 1 km wide zone of deformation that changes in strike and slip rate from 275° and 16 ± 5 mm/yr in the southwest, to 235° and 2 to 4.8 mm/yr in the northeast. Slip is transferred from the Mt Fyffe section to the Jordan thrust and related structures. Deformation along the Mt Fyffe section has been divided into four structural domains, from southeast to northwest: an extensional step-over, a series of four en-echelon wedges, a contractional step-over, and a contractional domain. Near surface fault zone kinematics recorded by tectonic geomorphic landforms are interpreted to reflect the change in strike of the fault zone, topographic loading and the related fault zone break-out along the range front. The south-western Mt Fyffe section has ruptured at least once between 660 AD and 1800 AD, and the north-eastern end ruptured at least once between 1410 and 1640 AD, and possible since 1640 AD. A rupture of the Mt Fyffe section with the Conway section is the foundation fault for Kaikoura. It is estimated to have a Mmax of greater than 7. Probabilistic seismic hazard models (Stirling et al., 2002; in press) estimate a rupture of the Hope fault will result in peak ground accelerations (PGA) for the 150 and 475 year events at Kaikoura of 0.45 to 0.6 g and 0.85 to 2.0 g (midpoints) respectively. Results of a deterministic seismic hazard assessment using the foundation fault, indicate PGA at the Kaikoura township will be between 0.64 g (after Stirling et al, 2000) and 0.31 g (after McVerry et al 2006), lower than that calculated by probabilistic methods. Detailed geomorphic mapping has defined two levels of seismic hazard avoidance zones along the Mt Fyffe rangefront. Zone A contains major structures that accommodate most offset and Zone B contains secondary, smaller scale deformation.
36

Passive and Semi-Active Tuned Mass Damper Building Systems.

Chey, Min Ho January 2007 (has links)
This thesis explores next generation passive and semi-active tuned mass damper (PTMD and SATMD) building systems for reducing the seismic response of tall structures and mitigating damage. The proposed structural configuration separates the upper storey(s) of a structure to act as the 'tuned' mass, either passively or semi-actively. In the view point of traditional TMD system theory, this alternative approach avoids adding excessive redundant mass that is rarely used. In particular, it is proposed to replace the passive spring damper system with a semi-active resetable device based system (SATMD). This semi-active approach uses feedback control to alter or manipulate the reaction forces, effectively re-tuning the system depending on the structural response. In this trade-off parametric study, the efficacy of spreading stiffness between resetable devices and rubber bearings is illustrated. Spectral analysis of simplified 2-DOF model explores the efficacy of these modified structural control systems and the general validity of the optimal derived parameters is demonstrated. The end result of the spectral analysis is an optimally-based initial design approach that fits into accepted design methods. Realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. This probabilistic approach avoids bias toward any particular type of ground motion or frequency content. Statistical analysis of the performance over these suites thus better indicates the true overall efficacy of the PTMD and SATMD building systems considered. Several cases of the segregated multi-storey TMD building structures utilising passive devices (PTMD) and semi-active resetable devices (SATMD) are described and analysed. The SATMD building systems show significant promise for applications of structural control, particularly for cases where extra storeys might be added during retrofit, redevelopment or upgrade. The SATMD approach offers advantages over PTMD building systems in the consistent response reductions seen over a broad range of structural natural frequencies. Using an array of performance metrics the overall structural performance is examined without the typically narrow focus found in other studies. Performance comparisons are based on statistically calculated storey/structural hysteretic energy and storey/structural damage demands, as well as conventional structural response performance indices. Overall, this research presents a methodology for designing SATMD building systems, highlighting the adaptable structural configuration and the performance obtained. Thus, there is good potential for SATMD building systems, especially in retrofit where lack of space constrains some future urban development to expand upward. Finally, the approach presented offers an insight into how rethinking typical solutions with new technology can offer dramatic improvements that might not otherwise be expected or obtainable.
37

Tectonic motions and earthquake deformation in Greece from GPS measurements

Clarke, Peter John January 1996 (has links)
Sites in a 66-station geodetic network in central Greece have been occupied up to six times since 1989 using GPS surveying, and accurate positions have been computed using fiducially-improved or precise orbits. Site velocities are calculated under the assumption that they are constant with time, after correcting for co-seismic effects, and that the position of the fixed base station (and hence the entire network) may be subject to small errors. Low-order polynomial expressions do not fit the velocity field well. The pattern of observed strain closely resembles that derived from independent geodetic observations made over a hundred-year time-scale. Significant geodetic strain is observed across the Gulf of Korinthos, even after the co-seismic displacement field of the Ms=6.2 1995 Egion earthquake has been removed by forward modelling. Geodetic strain is higher in the western than eastern Gulf, in contrast to the seismic strain which is similar throughout. Seismic strain matches geodetic strain in the east, but a significant deficit of seismic moment exists in the west which may represent a high earthquake hazard in the medium term. The Ms=6.6 1995 Grevena earthquake struck a previously seismically quiet region well covered by a recent triangulation / trilateration survey. Ninety-one points from this network were reoccupied with GPS immediately after the earthquake, and site displacements computed. To invert for the earthquake source parameters from the geodetic displacement field, a novel inversion scheme is used which combines the Monte-Carlo and simplex approaches. A priori parameters are not required, even though the inverse problem is strongly nonlinear. The resulting focal mechanism agrees well with the global CMT solution and locally observed aftershocks, but implies a significantly higher scalar moment than do seismological studies. A network for observing post-seismic deformation has been established, which in view of the low background seismicity seems likely to provide significant results.
38

Estimation Of Earthquake Insurance Premium Rates Based On Stochastic Methods

Deniz, Aykut 01 January 2006 (has links) (PDF)
In this thesis, stochastic methods are utilized to improve a familiar comprehensive probabilistic model to obtain realistic estimates of the earthquake insurance premium rates in different seismic zones of Turkey. The model integrates the information on future earthquake threat with the information on expected earthquake damage to buildings. The quantification of the future earthquake threat is achieved by making use of the seismic hazard analysis techniques. Due to the uncertainties involved, the hazard that may occur at a site during future earthquakes has to be treated in a probabilistic manner. Accessibility of past earthquake data from a number of different data sources, encourages the consideration of every single earthquake report. Seismic zonation of active earthquake generating regions has been improved as recent contributions are made available. Finally, up-to-date data bases have been utilized to establish local attenuation relationships reflecting the expected earthquake wave propagation and its randomness more effectively. The damage that may occur to structures during future earthquakes involves various uncertainties and also has to be treated in a probabilistic manner. For this purpose, damage probability matrices (DPM), expressing what will happen to buildings, designed according to some particular set of requirements, during earthquakes of various intensities, are constructed from observational and estimated data. With the above considerations, in order to demonstrate the application of the improved probabilistic method, earthquake insurance premium rates are computed for reinforced concrete and masonry buildings constructed in different seismic zones of Turkey.
39

Preliminary Evaluation of Seismic Potential of the Cottage Grove Fault System in Southern Illinois as Determined using the EarthScope Transportable Array

Petruska, Jon 01 August 2018 (has links)
The Cottage Grove Fault System is an East-West trending system of strike slip faults within Southern Illinois that has been explored for mineral resources but never systematically examined for seismicity or seismic hazard. Due to its location between the seismically active Wabash Valley, Saint Genevieve, and the New Madrid Seismic Zones, and the prevalence of nearby structural features, this fault system merits its own systematic study. Using existing data from the EarthScope Transportable Array, seismic activity and implications for hazard are explored through microseismicity. Over a two-year period, the closest two seismometers to the CGFS were utilized to search for microseismicity along the fault. Analysis was done through visually assessing waveforms and frequency-amplitude plots, which can help differentiate mine blasts and earthquakes based on the frequency content of the waveform. During the 2-year deployment, a total of 94 seismic events were detected, with 5 previously unrecorded earthquakes located within the Cottage Grove Seismic Zone, although none were located on the main fault. The greatest magnitude of the Cottage Grove Fault System events found was an M_L 1.5 and the smallest an M_L 0.8. The methodology found all seismic events mb 2.3 or greater listed by the Center for Earthquake Research and Information (CERI) catalog, within a 150 km radius. Missed events from the CERI catalog were small and distant. Finding earthquakes near the Cottage Grove Fault System undetected by the CERI network demonstrates that the region has a degree of previously undetected seismic activity. Preliminary event detection is better explained by a b-value of 0.7 than a b-value of 1.0, suggesting current estimates of the hazard of the CGFS is underestimated.
40

A Method for Reconstructing Historical Destructive Earthquakes Using Bayesian Inference

Ringer, Hayden J. 04 August 2020 (has links)
Seismic hazard analysis is concerned with estimating risk to human populations due to earthquakes and the other natural disasters that they cause. In many parts of the world, earthquake-generated tsunamis are especially dangerous. Assessing the risk for seismic disasters relies on historical data that indicate which fault zones are capable of supporting significant earthquakes. Due to the nature of geologic time scales, the era of seismological data collection with modern instruments has captured only a part of the Earth's seismic hot zones. However, non-instrumental records, such as anecdotal accounts in newspapers, personal journals, or oral tradition, provide limited information on earthquakes that occurred before the modern era. Here, we introduce a method for reconstructing the source earthquakes of historical tsunamis based on anecdotal accounts. We frame the reconstruction task as a Bayesian inference problem by making a probabilistic interpretation of the anecdotal records. Utilizing robust models for simulating earthquakes and tsunamis provided by the software package GeoClaw, we implement a Metropolis-Hastings sampler for the posterior distribution on source earthquake parameters. In this work, we present our analysis of the 1852 Banda Arc earthquake and tsunami as a case study for the method. Our method is implemented as a Python package, which we call tsunamibayes. It is available, open-source, on GitHub: https://github.com/jwp37/tsunamibayes.

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