A 3D velocity model and 3D wave propagation code have been employed to simulate long-period ground motions in the upper Mississippi embayment. This region is exposed to seismic hazard in the form of large earthquakes in the New Madrid seismic zone and observational data are sparse, making simulation a valuable tool for predicting the effects of large events. These simulations were undertaken in order to estimate ground-motion characteristics and to investigate the influence of the 3D embayment structure and finite-fault mechanics. There are three primary fault zones in the New Madrid seismic zone, each of which was likely associated with one of the three main shocks of the 1811-1812 earthquake sequence. For this study, three simulations have been conducted on each major segment, evaluating the effects of different epicentral locations and rupture directions on ground motions. The full wave field up to a frequency of 0.5 Hz was computed on a 200 × 200 × 50 km3 volume, and up to a frequency of 1.0 Hz on a 100 × 100 × 50 km3 volume, using a staggered-grid finitedifference code. Peak horizontal velocity, bracketed durations, and pseudospectral accelerations were calculated at the free surface. Animations showing the evolution of peak horizontal velocity through time at the free surface were also generated. The New Madrid seismic zone simulations indicate that for the considered bandwidth, finite-fault mechanics such as fault proximity, directivity effect, and slip distribution exert the most control on ground motions. The 3D geologic structure of the upper Mississippi embayment also influences ground motion, with indications that the bedrock surface acts as a wave guide, trapping waves in shallow, low-velocity parts of the embayment.

A common issue with the power grid during natural disasters is low availability. Many critical applications that are required during and after natural disasters, for rescue and logistical operations require highly available power supplies. Microgrids with distributed generation resources along with the grid provide promising solutions in order to improve the availability of power supply during natural disasters. However, distributed generators (DGs) such as diesel gensets depend on lifelines such as transportation networks whose behavior during disasters affects the genset fuel delivery systems and as a result affect the availability. Renewable sources depend on natural phenomena that have both deterministic as well as stochastic aspects to their behavior, which usually results in high variability in the output. Therefore DGs require energy storage in order to make them dispatchable sources. The microgrids availability depends on the availability characteristics of its distributed generators and energy storage and their dependent infrastructure, the distribution architecture and the power electronic interfaces. This dissertation presents models to evaluate the availability of power supply from the various distributed energy resources of a microgrid during natural disasters. The stochastic behavior of the distributed generators, storage and interfaces are modeled using Markov processes and the effect of the distribution network on availability is also considered. The presented models supported by empirical data can be hence used for microgrid planning. / text

The Master of Engineering Management Project was sponsored by the Canterbury Earthquake Recovery Authority (CERA) and consisted of two phases: The first was an analysis of existing information detailing the effects of hazardous natural events on Canterbury Lifeline Utilities in the past 15 years. The aim of this “Lessons Learned” project was to produce an analysis report that identified key themes from the research, gaps in the existing data and to provide recommendations from these “Lessons Learned.” The Second phase was the development of a practical “Disaster Mitigation Guideline” that outlined lessons in the field of Emergency Sanitation. This research would build upon the first stage and would draw from international reference to develop a guideline that has practical implementation possibilities throughout the world.

The purpose of this thesis is to evaluate the seismic response of the UC Physics Building based on recorded ground motions during the Canterbury earthquakes, and to use the recorded response to evaluate the efficacy of various conventional structural analysis modelling assumptions. The recorded instrument data is examined and analysed to determine how the UC Physics Building performed during the earthquake-induced ground motions. Ten of the largest earthquake events from the 2010-11 Canterbury earthquake sequence are selected in order to understand the seismic response under various levels of demand. Peak response amplitude values are found which characterise the demand from each event. Spectral analysis techniques are utilised to find the natural periods of the structure in each orthogonal direction. Significant torsional and rocking responses are also identified from the recorded ground motions. In addition, the observed building response is used to scrutinise the adequacy of NZ design code prescriptions for fundamental period, response spectra, floor acceleration and effective member stiffness. The efficacy of conventional numerical modelling assumptions for representing the UC Physics Building are examined using the observed building response. The numerical models comprise of the following: a one dimensional multi degree of freedom model, a two dimensional model along each axis of the building and a three dimensional model. Both moderate and strong ground motion records are used to examine the response and subsequently clarify the importance of linear and non-linear responses and the inclusion of base flexibility. The effects of soil-structure interaction are found to be significant in the transverse direction but not the longitudinal direction. Non-linear models predict minor in-elastic behaviour in both directions during the 4 September 2010 Mw 7.1 Darfield earthquake. The observed torsional response is found to be accurately captured by the three dimensional model by considering the interaction between the UC Physics Building and the adjacent structure. With the inclusion of adequate numerical modelling assumptions, the structural response is able to be predicted to within 10% for the majority of the earthquake events considered.

No description available.

The processes associated with magma injection at shallow depths within the crust have been the topic of many geophysical studies, some investigating the seismicity that accompanies volcanic activity and others attempting to map the subsurface extent and geometry of the resulting magma bodies. The aim of this study is to obtain a better understanding of these processes by investigating the nature of seismic signals that accompany volcanic eruptions and by seismically imaging a magma body beneath a mid-ocean ridge, both located on, or adjacent to Iceland. The seismic phenomena associated with the 1996 Vatnajӧkull subglacial eruption in central Iceland, have been studied using data recorded by both temporary (HOTSPOT) and permanent (SIL) seismic networks. These networks comprise 60 broadband and short-period three-component seismographs and cover most parts of the country. Two very active volcanic systems, Bárdarbunga and Grimsvӧtn, are situated underneath the Vatnajokull ice cap. The volcanoseismic signals recorded there were categorised according to their waveform shape and frequency content, into three groups: (a) low-frequency events (1-2 Hz); (b) mixed-frequency events (1-4 Hz); and (c) volcanic tremor. The eruption was preceded by intense seismic activity which began with a = 5.6 earthquake located at the Bárdarbunga volcanic system. The epicentres of the earthquake swarm that followed the M(_w), = 5.6 event initially delineated the Bárdarbunga caldera rim and then migrated towards Grimsvӧtn, to a place where a fissure was later observed. Pre-eruptive tremor started at least two days before the eruption as a harmonic signal around five narrow frequency bands (0.5-0.7, 1.6, 2.2, 2.8 and 3.2 Hz). Co-eruptive tremor started as a broadband, continuous signal which evolved into low-amplitude background tremor interrupted by high-amplitude, cigar-shaped bursts. Further analysis revealed that continuous tremor and the cigar-shaped bursts had all the characteristics of low- dimensional chaotic signals. Geophysical and geochemical evidence suggest that a lateral migration of magma from Bárdarbunga facilitated the rupture of the roof of a magma chamber, situated at the fissure area, which subsequently erupted as tephra on the glacier. The second phase of the RAMESSES (Reykjanes Ridge Axial Melt Experiment: Structural Synthesis from Electromagnetic and Seismics) experiment involved the acquisition of multichannel seismic reflection data from 39 along- and across-axis lines shot over the magmatically active 57º 45'N axial volcanic ridge. The data from one along-axis line were processed using a variety of techniques that mainly aimed at reducing the large amount of coherent noise present, a result of scattered energy at the rough seabed. The final processed section revealed a number of reflection events that could be interpreted as intra-crustal reflections, originating from the interface between pillow lavas and sheeted dykes, and from the top part of a thin melt lens.

In this thesis, I present results that broadly fall into two themes. The first involves understanding active tectonic and magmatic processes at mid-ocean ridges. The second involves using small stress changes due to the tides to probe earthquake processes at mid-ocean ridges. The four main results of my thesis are as follow: (1) The spatiotemporal evolution of an eruption at a fast-spreading mid-ocean ridge, the East Pacific Rise, is now characterized and understood to be mainly controlled by the buildup of tectonic stress to a critical level rather than magma overpressure. (2) Microearthquakes at the East Pacific Rise are found to be strongly modulated by tides in the years before an eruption but not immediately after the eruption, suggesting the potential utility of tidal triggering strength for eruption forecasting. (3) Earthquake size-frequency distribution, often quantified using the b value, is shown to vary systematically with tidal stresses which lends support to the use of earthquake b value as an in-situ stressmeter. (4) The 2015 Axial Seamount eruption is revealed to be preceded by variable rates of melt influx into the shallow reservoir, highlighting the short-timescale variability of magmatic systems as they are primed for an eruption.

The New Madrid Seismic Zone is well known for its historical seismicity, most notably the 1811-12 New Madrid, MO earthquakes and to a lesser extent the 1895 Charlston, MO earthquake. It has been 124 years since an earthquake larger than M 5.1 occurred in the area. The debate of whether the New Madrid Seismic Zone is an active system or a system in decline has remained a contentious topic when interpreting the intricacies and challenges of an intraplate seismic system. This thesis focuses on an overlooked parameter in the already complex issue regarding the seismic hazard of the New Madrid Seismic Zone. In the early part of the 20th century the Little River Drainage District excavated 9.7 x 109 metric tons of overburden and drained approximately 5000 km2 from within the New Madrid Seismic Zone. Our model demonstrates that the Little River Drainage District resulted in a likely perturbation of the seismic system. The overburden removal, coupled with a reduction of the water column has moved the system away from failure when interpreted in the context of regional stress orientation in relation to the geographic orientation of the Little River Drainage District. This potentially explains the apparent lack of moderate to large events over the past century in the New Madrid Seismic Zone.

Les phénomènes d’instabilité générés par les séismes dans les pentes représentent un risque naturel majeur à l’échelle mondiale. Ce risque a, de plus, tendance à croître du fait d’une urbanisation croissante dans des zones à fort aléa, comme en témoignent de nombreux évènements catastrophique à travers le passé. Pour garantir la sécurité des personnes et des biens face à ce type d’aléa, il faut améliorer les prédictions des déplacements générés par les séismes dans les pentes.Les premiers travaux scientifiques visant à corréler les caractéristiques des instabilités dans les pentes aux paramètres sismiques sont de nature empirique et remontent aux années 1980. Ces méthodes ne permettent pas d’expliquer tous les mouvements de terrain observés à travers le monde, notamment lorsque les effets de site modifient sensiblement la distribution des mouvements dans les pentes et génèrent des déplacements plus grands ou plus petits que ceux prédits par les lois empiriques qui négligent les effets de site.La première partie de cette thèse présente une nouvelle base de données mondiale de 277 glissements de terrain d’origine sismique ou non. L’analyse statistique conduite sur les données de cette base a montré que la forme géométrique moyenne des glissements de terrain reste stable lorsque le volume des instabilités augmente.La deuxième partie de la thèse est dédiée à l’analyse de la stabilité du glissement de terrain de Diezma (Espagne) au moyen de trois méthodes : la Méthode de NEWMARK (1965) basée sur le principe de l’équilibre limite en 2D qui suppose des conditions elasto-parfaitement-plastiques ; l’analyse par différences finies dans le domaine temporel avec le code FLAC en 2D et en 3D qui suppose des conditions visco-elasto-parfaitement-plastiques ; et l’analyse par recombinaison modale dans le domaine fréquentiel avec le code CESAR-LCPC en 2D et en 3D qui suppose des conditions visco-élastiques.Situé dans une région sismiquement active, le glissement de terrain de Diezma est susceptible d’être affecté par des séismes. Une analyse des déplacements induits dans ce versant par onze signaux sismiques différents a été menée dans l’objectif d’établir des corrélations entre les paramètres macro-sismiques des scenarios sismiques appliqués et les déformations calculées par les trois méthodes.Les résultats montrent des différences marquées à la fois qualitatives et quantitatives. Les conclusions principales sont : (a) Les déplacements obtenus par les trois méthodes ont des ordres de grandeur différents et peuvent donc conduire à une surestimation ou à une sous-estimation des déplacements ; (b) Les deux méthodes numériques montrent que les déplacements sont fortement conditionnés par la géométrie des modèles ; seule la méthode par différences finies fait apparaître une réponse en termes de déplacements qui dépend du scénario sismique considéré; (c) Les résultats des simulations2D et 3D ne sont pas comparables ; des analyses complémentaires doivent encore être menées pour guider l’utilisateur dans le choix de la méthode la plus appropriée; (d) La Méthode de NEWMARK (1965), dont l’utilisation reste très répandue de nos jours, est tout à fait appropriée à l’étude de cas simples mais elle peut se révéler inexacte lorsque la structure géologique / topographique du versant conduit à un fort effet de site car ce dernier n’est pas pris en compte par cette méthode / Seismically induced slope deformation is a worldwide common phenomenon that poses an increasing and considerable threat to fast expanding urbanization, and a great number of catastrophic events throughout the past attest thereof. For this reason, displacement predictions allowing for proper slope surveillance became a major concern.Early attempts to relate slope failures to seismic parameters are of empirical nature and date back to the 1980s. Although having proven stable, these relations are frequently disturbed by site effects causing outliers in terms of smaller or greater displacements than expected.The first part of this thesis presents a newly build chronological database of 277 globally distributed seismically and non-seismically induced landslides. A comprehensive statistical analysis was conducted on the data of this database with the main result that – statistically seen – the average geometrical shapes of landslides differ only proportionally.The second part of the thesis is dedicated to a comparative slope stability analysis of the Diezma Landslide (Spain) by means of three methods: the limit-equilibrium based NEWMARK-Method (1965) in 2D under elasto-perfectly-plastic conditions; finite-difference analysis in the time domain with the code FLAC in 2D and 3D under visco-elasto-perfectly-plastic conditions; and modal recombination analysis in the frequency domain with the finite-element code CESAR-LCPC in 2D and 3D under visco-elastic conditions.Located in a seismically active region, the Diezma Landslide is likely to be affected by earthquakes and was therefore considered as a suitable model case. A broad analysis of expected displacements was conducted using eleven strong-motion seismic scenarios. Moreover, the thesis searches for potential relations between macro-seismic parameters of the applied earthquake scenarios and the predicted deformations obtained from the three methods.It appeared that – due to the functionality of the methods – results differ quantitatively as well as qualitatively, and so does their suitability. Major findings are: (a) Results from the three methods are of different orders of magnitude and, thus, can easily lead to over- or under-estimations of displacements; (b) Both numerical methods reveal a strong influence of the model-geometry on the predicted displacements, whereas a scenario-dependent slope behavior manifested itself only within the finite difference analysis; (c) The switch from 2D to 3D does not necessarily result in a similar performance in each dimension and results must be critically judged before further use; (d) The NEWMARK-Method (1965) has proven itself once more to be appropriate for first slope assessments but not for sophisticated evaluations of ground response to seismic shaking

We address questions related to the parameterization of two distinct types of seismic sources: earthquakes and underground nuclear explosions. For earthquakes, we focus on the improvement of location parameters, latitude and longitude, using relative measurements of spatial cluster of events. For underground nuclear explosions, we focus on the seismic source model, especially with regard to the generation of surface waves. We develop a procedure to improve relative earthquake location estimates by fitting predicted differential travel times to those measured by cross-correlating Rayleigh- and Love-wave arrivals for multiple earthquakes recorded at common stations. Our procedure can be applied to populations of earthquakes with arbitrary source mechanisms because we mitigate the phase delay that results from surface-wave radiation patterns by making source corrections calculated from the source mechanism solutions published in the Global CMT Catalog. We demonstrate the effectiveness of this relocation procedure by first applying it to two suites of synthetic earthquakes. We then relocate real earthquakes in three separate regions: two ridge-transform systems and one subduction zone. In each scenario, relocated epicenters show a reduction in location uncertainty compared to initial single-event location estimates. We apply the relocation procedure on a larger scale to the seismicity of the Eltanin Fault System which is comprised of three large transform faults: the Heezen transform, the Tharp transform, and the Hollister transform. We examine the localization of seismicity in each transform, the locations of earthquakes with atypical source mechanisms, and the spatial extent of seismic rupture and repeating earthquakes in each transform. We show that improved relative location estimates, aligned with bathymetry, greatly reduces the localization of seismicity on each of the three transforms. We also show how improved location estimates enhance the ability to use earthquake locations to address geophysical questions such as the presence of atypical earthquakes and the nature of seismic rupture along an oceanic transform fault. We investigate the physical basis for the mb-MS discriminant, which relies on differences between amplitudes of body waves and surface waves. We analyze observations for 71 well-recorded underground nuclear tests that were conducted between 1977-1989 at the Balapan test site near Semipalatinsk, Kazakhstan in the former Soviet Union. We combine revised mb values and earlier long-period surface-wave results with a new source model, which allows the vertical and horizontal forces of the explosive source to be different. We introduce a scaling factor between vertical and horizontal forces in the explosion model, to reconcile differences between body wave and surface wave observations. We find that this parameter is well correlated with the scaled depth of burial for UNEs at this test site. We use the modified source model to estimate the scaled depth of burial for the 71 UNEs considered in this study.