Earthquake Segment Boundaries and Tsunamigenic Faults of the Kodiak Segment, Alaska-Aleutian Subduction Zone

The most recent megathrust earthquake to impact the Alaska subduction zone was the M9.2 Great Alaska earthquake of 1964. This multi-segment rupture spanned over 700 km of the plate boundary and engendered both local and trans-Pacific tsunamis. The Kodiak Islands region served as the southwestern limit to rupture. The nature of past megathrust segmentation for the Alaska subduction zone has been largely hypothesized through paleoseismological methods and the Kodiak region in particular has not received a comprehensive geophysical characterization of its inferred segment boundaries. I analyze multiple geophysical datasets (e.g. seismic reflection, earthquake, potential fields) to understand the spatiotemporal relationships between subduction, accretion, lower and upper plate structure, and tsunamigenic fault hazard in the context of the known megathrust earthquake record and other interseismic observations for the Kodiak region. The northeast Kodiak segment boundary is defined by the subducting 58° fracture zone, which can be traced below the forearc using magnetic and gravitational fields. Subduction of this feature is expressed on post-1964 seismicity, is consistent with oblique shortening, and manifests itself within the upper plate as the Portlock Anticline. The southwest segment boundary marks the transition between the Kodiak and Semidi segments. It is shown to be a region that shifts from significant margin erosion to a region of imbricate thrusting and margin growth. These two zones are bound by fracture zone subduction. I furthermore independently constrain and compliment paleoseismological models of joint Kodiak and Semidi segment rupture by identifying and characterizing a through-going marine fault zone across this segment boundary. Finally, I revisit the source mechanisms for the local tsunami that inundated the Kodiak Islands as a result of the 1964 earthquake. I provide a new tsunamigenic source model that suggests discrete uplift of the Kodiak Islands shelf fault system and illuminate its along-strike rupture variability throughout the Holoecene epoch. My findings suggest segment boundaries across Kodiak have a clear geophysical expression and a multi-dataset approach is necessary to decipher tectonic controls on megathrust segmentation

How the Transition Region Along the Cascadia Megathrust Influences Coseismic Behavior: Insights From 2‐D Dynamic Rupture Simulations

There is a strong need to model potential rupture behaviors for the next Cascadia megathrust earthquake. However, there exists significant uncertainty regarding the extent of downdip rupture and rupture speed. To address this problem, we study how the transition region (i.e., the gap), which separates the locked from slow‐slip regions, influences coseismic rupture propagation using 2‐D dynamic rupture simulations governed by a slip‐weakening friction law. We show that rupture propagation through the gap is strongly controlled by the amount of accumulated tectonic initial shear stress and gap friction level. A large amplitude negative dynamic stress drop is needed to arrest downdip rupture. We also observe downdip supershear rupture when the gradient in effective normal stress from the locked to slow‐slip regions is dramatic. Our results justify kinematic rupture models that extend below the gap and suggests the possibility of high‐frequency energy radiation during the next Cascadia megathrust earthquake.Plain Language SummaryHow large, deep, and damaging a future earthquake will be depends on factors such as energy release that must be constrained by precise observations of previous earthquakes in the same area. But such data are rarely available. Instead, computer models of earthquakes guided by the laws of physics can provide us with estimates of potential ground shaking for a future event. In our study, we design two‐dimensional earthquake simulations for the Cascadia fault below the northwestern United States coast and test different hypotheses for how stress may be accumulating at depth along this fault. Our models focus on a portion of the fault referred to as the “gap.” The gap physically separates a shallow region that slips during large earthquakes from a deeper region that experiences intermittent slip between large earthquakes. A gap region similar to that in Cascadia is also found in Japan, Mexico, and around other active faults worldwide. We find that our simulated rupture is able to extend to deeper regions at faster speeds given the current understanding of stress levels and earthquake fault friction in the gap. While this work represents only a first step toward understanding how stresses and friction influence how the Cascadia fault might slip, it lays the foundation for modeling more complex physics that can help scientists better predict shaking from seismic waves.Key PointsWe examine dynamic source effects on along‐dip rupture propagation for a Cascadia megathrust earthquakeSimulated earthquake rupture is able to penetrate through the transition zone and reach the deeper slow‐slip regionOur results underscore the potential for a deeper downdip rupture and faster rupture speed than previously assumed in kinematic modelsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148357/1/grl58609.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148357/2/grl58609_am.pd

Physics-based Simulations of Large Earthquake Rupture Processes

A complete description of how an earthquake occurs can be achieved with a physically self-consistent modeling framework where wave propagation is combined with fracture mechanics to simulate the initiation, growth, and arrest of fault motion. To this end, dynamic rupture simulations are used to reproduce or predict dynamic and static deformations through time and space and give insight into the frequency-dependent rupture process. This dissertation assessed the rupture dynamics of large earthquakes in two separate tectonic environments using two different approaches. The major contribution of this work is the use of high-resolution geophysical data to constrain rupture dynamics and uncover controls on future seismic hazard in subduction or strike-slip fault systems. In chapter 2 I developed 2-D dynamic rupture simulations focused on the transition zone region between the locked and creeping regions of the Cascadia megathrust. I used geode- tic inversions for shear stress-rate to constrain possible dynamic stress-drop amplitudes within the locked and transition regions. While the initial conditions suggested an energetically unfavorable condition for deeper rupture, my models captured the exact opposite. Deeper rupture at speeds exceeding the shear-wave velocity (supershear) is possible given the geodetic inversion results, unless the transition region has a dynamic frictional behavior that strongly increases in response to slip. This study suggested the possibility of a wider Cascadia earthquake source model and that one possible mechanism for high-frequency energy radiation down-dip might be when the there is a supershear rupture transition. In chapter 3 I extended the 2-D simulation framework and developed the first fully dynamic 3-D rupture simulations for the Cascadia subduction zone. I developed an approach to estimate dynamic stress-drop along the Cascadia megathrust using geodetic coupling models of slip-rate deficit. I found that the relative dynamic stress-drop amplitude in the central Cascadia region exerts the greatest influence on whether or not margin-wide ruptures can develop. I also showed several non-unique simulations that can provide a close match to subsidence data from the last Cascadia megathrust event in 1700 A.D. - under- scoring the importance of offshore geodetic data to rule out competing ideas of interseismic strain accumulation offshore. Finally, chapter 4 investigated elastic stresses radiated from the 2019 Ridgecrest Sequence mainshock using 2-D dynamic rupture simulations. I focused on the dynamic stress changes experienced by the Garlock fault, a major strike-slip fault in the Eastern California Shear zone, during the coseismic rupture phase. I found that peak Coulomb stresses arrive at the Garlock < 1 minute from the mainshock nucleation. The simulations resolved key kinematic rupture parameters such as low mainshock rupture speeds (≤ 2.0 km/s) and slip amplitudes through the hypocenter.PHDEarth and Environmental SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/167945/1/ramosmd_1.pd

Estudo de filmes finos de TixOy depositados em aço-carbono para aplicação antincrustante

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Programa de Pós-Graduação em Engenharia e Ciências Mecânicas, Joinville, 2016.Os processos de bioincrustação marinha são frequentemente observados em diversos materiais utilizados pela indústria naval e oceânica. Atualmente, há um grande esforço no desenvolvimento de pesquisas científicas que conduzam a soluções para este problema, com mínima agressão ambiental ao ambiente marinho. Entre os materiais já desenvolvidos para esta finalidade, podem ser citadas as tintas à base de TBT (tributilestanho), que tem grande eficiência, porém são muito tóxicas. O dióxido de titânio (TiO2) pode ser uma alternativa, devido ao desempenho antimicrobiano e atóxico. Considerando a relevância do problema a nível global e ausência de uma solução ecologicamente correta, foi realizada avaliação do potencial antincrustante de filmes finos de TixOy depositados por Triodo Magnetron Sputtering Reativo em amostras de aço-carbono. Após as deposições as amostras foram colocadas em ambiente marinho natural, na marina Cubatão e monitoradas para o estudo do processo antincrustante. O estudo sistemático revelou a formação de filmes finos de TiO2 cristalinos para teores de 39% e 62% de O2 e 100% para amorfo. As estruturas cristalinas caracterizam-se pela presença das fases anatase e rutile. Desenvolveu uma metodologia de estudo experimental para avaliação da exposição ao ambiente marinho, caracterização dos filmes finos e da bioincrustação. Mesmo não sendo possível visualizar a bioincrustação, a análise da quantidade de estruturas aderidas permite uma conclusão indireta a respeito do potencial antincrustante, já que a possibilidade de crescimento de seres vivos está diretamente relacionada com a facilidade de adesão à superfície. Neste sentido, as amostras com TiO2 cristalino apresentaram evidente menor proporção de estruturas aderidas em comparação com a amostra amorfa.Abstract : Marine biofouling processes are frequently observe in various materials used by the naval and oceanic industries. Currently, there is a great effort in the development of scientific researches that lead to solutions to this problem, with minimal environmental aggression to the marine environment. Among the materials already developed for this purpose, can be cited TBT (tributyltin) based paints, which have great efficiency, but are very toxic. Titanium dioxide (TiO2) may be an alternative, due to antimicrobial and non-toxic performance. Considering the relevance of the problem at global level and the absence of an ecologically correct solution, an evaluation was made of the antifouling potential of TixOy thin films deposited by Reactive Magnetron Sputtering Triodo in carbon steel samples. After deposition the samples were placed in a natural marine environment at the Cubatão marina and monitored for the study of the antifouling process. The systematic study revealed the formation of thin films of crystalline TiO2 for contents of 39% and 62% of O2 and 100% for amorphous. The crystalline structures are characterized by the presence of the anatase and rutile phases. It were developed an experimental study methodology to evaluate exposure to the marine environment, characterization of thin films and biofouling. Although it is not possible to visualize the biofouling, the analysis of the amount of adhered structures allows an indirect conclusion regarding the antifouling potential, since the possibility of growth of living beings is directly related to the ease of adhesion to the surface. In this sense, samples with crystalline TiO2 showed an evident lower proportion of adhered structures in comparison with the amorphous sampl

Diseño del Sistema de Alcantarillado Pluvial en el Control de Inundaciones de la Avenida Tupac Amaru

La investigación tuvo como problema general: ¿Cuál será el diseño del sistema de alcantarillado pluvial en el control de inundaciones de la avenida Túpac Amaru?, el objetivo general fue: Realizar el diseño del sistema de alcantarillado pluvial en el control de inundaciones de la avenida Túpac Amaru, y la hipótesis general fue: El control de inundaciones de la avenida Túpac Amaru es posible mediante el diseño del sistema de alcantarillado pluvial. El método de investigación fue el científico, el tipo de investigación fue aplicado, el nivel de investigación fue descriptivo – explicativo y el diseño de investigación fue no experimental de corte transversal. La población correspondió a la Avenida Túpac Amaru del distrito de El Tambo - Huancayo, se tomó como muestra el tramo de la avenida Túpac Amaru av. Mariscal castilla - Av. Razuri; Av. Razuri tramo: Av. Túpac Amaru - Jr. 27 de junio y Jr. 27 de junio tramo: Jr. Razuri - Jr. Chanchamayo. La conclusión general fue: Con el diseño del sistema de alcantarillado pluvial se logra un arrastre total de sedimento del interior del colector principal alcanzando la eficiencia al 100% de la operación del sistema de alcantarillado pluvial, con ello se consigue el control de las inundaciones de la avenida Túpac Amaru en el distrito de El Tambo - Huancayo

Propuesta de implementación de un Sistema Integrado bajo las normas ISO 9001: 2015, ISO 14001: 2015 e ISO 45001: 2018 para optimizar la gestión de los procesos en la Empresa Petrolera UNIPETRO ABC S.A.C., Talara - 2018

Actualmente en la Empresa Petrolera UNIPETRO ABC S.A.C. existen inconvenientes en las licitaciones y en las visitas técnicas de las entidades gubernamentales (OSINERGMIN, OEFA, PERUPETRO, entre otros), porque la documentación presentada inherente con las actividades que afectan a la calidad del servicio, medio ambiente, seguridad y salud ocupacional se encuentra obsoleta o simplemente no existe, además de la ausencia de controles y seguimiento respectivos, por lo que la presente investigación busca diseñar una propuesta de implementación de un sistema integrado bajo las normas ISO 9001: 2015, ISO 14001: 2015 e ISO 45001: 2018. Está fundamentada bajo las cláusulas de las normas ISO (International Organization for Standardization), siendo una investigación propositiva con diseño no experimental, considerando como población a las Jefaturas de área, además de información de las actividades que realiza la empresa, procedimientos y prácticas de trabajo, realizando la técnica de entrevista y revisión documentaria, se ha determinado el mapa de procesos y sus interrelaciones obteniéndose un proceso estratégico, tres operativos y ocho de soporte. Se realizó el diagnóstico de las normas ISO obteniéndose el 17% de implementación, elaborándose un plan de trabajo para su puesta en marcha en 10 meses, dicha propuesta de implementación de las normas ISO tiene un costo de S/. 70 000, y que estaría financiado por el Programa Innóvate Perú del Ministerio de la Producción (PRODUCE), con un máximo de S/ 45 000 por cada norma ISO