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.

Numerous observations suggest that the elastic description of the subduction earthquake cycles is incomplete. Micro-seismicity is recorded in active margins that are believed to be locked, while peculiar extensional earthquakes occur in convergent plate boundaries following tsunami earthquakes. The morphology of active margins, which evolves on time scales of 100s of kyr, shows similarities to ongoing deformation documented over 10–100 yrs and the coastal domains of Cascadia, Chile, and other subduction zones record long-term uplift. Lastly, the very threshold where faults break and earthquake nucleate has been vigorously debated for years. In this thesis, I combine various geophysical tools to study short- and long-term processes and learn how their interplay can shape the deformation field imparted by earthquake cycles, mainly in the upper plate of subduction zones. In the first chapter, I analyze surface heat flow measurements taken in the proximity of the southern Dead Sea fault to demonstrate its friction is 0.27±0.17. In the second chapter, I compute an updated horizontal and vertical GNSS velocity field for Bangladesh, Myanmar, and adjacent regions. I show that the Kabaw fault, which lies east of the primary thrust system, is accommodating shortening that was initially attributed to the main thrust and demonstrate that the Indo-Burma subduction is locked, converging, and capable of hosting great megathrust events. In the third chapter, I use thermomechanical models to show that reducing the dip angle of a subducting slab, on a timescale of millions of years, can result in extensional fault failure above a megathrust earthquake on timescales of seconds to months. In the fourth chapter, I demonstrate how the buildup of interseismic elastic stresses brings sections of the forearc into compressional failure, which yields irreversible uplift of the coastal domain per evidence from Chile. Finally, I argue that combining short- and long-term processes into subduction zone models can better mitigate tsunami and earthquake hazards. I show how long-term reduction of slab dip angle could culminate in devastating tsunamis. I argue that the collection of long-term uplift records of upper plates or volcanic arc migration can constrain slab dip changes and so may identify areas with increased tsunami potential. In addition, upper plate irreversible deformation should be introduced to earthquake rupture models as these may hold significant implications for understanding and mitigating earthquake hazards.

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.

LiDAR (Light Detection and Ranging) elevation data were collected in the Panther Creek Watershed, Yamhill County, Oregon in September and December, 2007, March, 2009 and March, 2010. LiDAR derived images from the March, 2009 dataset were used to map pre-historic, historic, and active landslides. Each mapped landslide was characterized as to type of movement, head scarp height, slope, failure depth, relative age, and direction. A total of 153 landslides were mapped and 81% were field checked in the study area. The majority of the landslide deposits (127 landslides) appear to have had movement in the past 150 years. Failures occur on slopes with a mean estimated pre-failure slope of 27° ± 8°. Depth to failure surfaces for shallow-seated landslides ranged from 0.75 m to 4.3 m, with an average of 2.9 m ± 0.8 m, and depth to failure surfaces for deep-seated landslides ranged from 5 m to 75m, with an average of 18 m ± 14 m. Earth flows are the most common slope process with 110 failures, comprising nearly three quarters (71%) of all mapped deposits. Elevation changes from two of the successive LiDAR data sets (December, 2007 and March, 2009) were examined to locate active landslides that occurred between the collections of the LiDAR imagery. The LiDAR-derived DEMs were subtracted from each other resulting in a differential dataset to examine changes in ground elevation. Areas with significant elevation changes were identified as potentially active landslides. Twenty-six landslides are considered active based upon differential LiDAR and field observations. Different models are used to estimate landslide susceptibility based upon landslide failure depth. Shallow-seated landslides are defined in this study as having a failure depth equal to less than 4.6 m (15 ft). Results of the shallow-seated susceptibility map show that the high susceptibility zone covers 35% and the moderate susceptibility zone covers 49% of the study area. Due to the high number of deep-seated landslides (58 landslides), a deep-seated susceptibility map was also created. Results of the deep-seated susceptibility map show that the high susceptibility zone covers 38% of the study area and the moderate susceptibility zone covers 43%. The results of this study include a detailed landslide inventory including pre-historic, historic, and active landslides and a set of susceptibility maps identifying areas of potential future landslides.

This study analyzed demographic differences and differential mortality between the Mississippi State Asylum (MSA) and the state of Mississippi. Using census records, Biennial Reports, death certificates, and vital statistics from the Mississippi State Board of Health, statistical methods including Kaplan-Meier survival analysis and Cox proportional hazard analysis were employed to explore significant differences in population demographics, hazard of death, and survivorship in general and with tuberculosis. Key results include proportionally more females in the MSA, increased hazard of death/decreased survivorship within the MSA compared to the State, and increased hazard of death/decreased survivorship for Black/AA individuals compared to their White/EA counterparts. This study demonstrates the intersectionality of sex, race, and institutionalization on survivorship and highlights the continued relevance of such issues in modern times, particularly regarding institutional treatment.

This thesis aims to solicit and elicit the view of experienced system safety analysts in the applicability and use of STPA, a hazard analysis derived from the STAMP-framework. The increase in complexity in systems elevates the chance of hazards and risks being obfuscated. Thus, the intention is to expand, deepen and theorize about the STPA-methodology in relation to the role of system safety analysts in Sweden. The results show that the greatest use of STPA might lie in integrating the desired procedural steps with the hazard analysis techniques used today. This is due to individual capabilities, guidance in identification and evaluation of risks, as well as the reductionistic perspective that prevails in society today. Unlike STPA’s claim for completeness, the impression of the system analysts is that absolute safety can never be guaranteed.

Hormesis is a nonlinear dose-response characterized by biological responses at low doses that are opposite to those observed at higher doses. Studies and review articles on hormesis are being published at an increasing rate by researchers from diverse disciplines and debate has emerged over the role hormesis in risk assessment. As a result, a survey was conducted to assess toxicologists and risk assessors knowledge and attitudes about the hormesis dose response. Study goals were to: 1) ascertain attitudes towards hormesis and other dose-response models, 2) identify whether acceptance or rejection of hormesis is based on knowledge of hormesis, predisposing values, or demographic characteristics, and 3) evaluate potential for response bias. The survey consisted of 44 questions pre-tested by 25 toxicologists and risk assessors. The survey was distributed via email to the membership of the Society of Toxicology and the Society for Risk Analysis, 9,500 potential respondents. The overall response rate was 17% (n= 1,463) with a completion rate over 87%. Major findings were that 50% of respondents indicated sufficient data exist to support the view hormesis occurs across a wide range of species and endpoints, 59% indicated evaluating potential benefits due to hormesis should be included in risk assessments, and 65% are in favor of modifying hazard assessment protocols to identify the presence of hormesis. Respondent characteristics such as: years of experience, society membership, education, residence, employment (excluding government and pharmaceutical companies), and political, economic or social views had little influence on opinion. One of the largest positive influences was experience with hormesis based on actual research; 79% of subjects who reported observing hormesis commonly in their studies agreed hormesis is broadly generalizable. The influence of non-response bias was evaluated through several internal and external measures. Despite a lower than hoped for response rate, but because of robust external validity measures, it is concluded that respondents’ opinions are likely a reasonable representation of the societies of which they are members. Because this is a baseline survey, a follow-up survey is in order. Future survey design should separately evaluate the science of dose-response from the regulatory approach to risk assessment.

The annual incidence of microbiological food borne disease in the United States ranges between 6.5 million to 33 million cases with as high as 9,000 deaths. There is a developing consensus that the Hazard Analysis and Critical Control Point (HACCP) concept is the most effective and rational means of assuring food safety from harvest to consumption. The first step in the application of the HACCP concept involves conducting a hazard analysis. It is essential that this procedure is performed correctly, because the subsequent plan and procedures developed to control the identified hazards are based on this critical first step. Recently the National Advisory Committee on Microbiological Criteria for Foods (NACMCF) and Codex Alimentarius have published information on HACCP principles and application, but have not provided a comprehensive method for conducting a hazard analysis. Guidance on hazard analysis issues such as the determination of significant hazards for inclusion in a HACCP plan, the probability of occurrence (risk), and hazard severity is lacking. Practical guidance for conducting a hazard analysis and applying Principle #1 was developed. A decision tree approach is proposed that provides a logical framework for deciding what hazards are to be included in the HACCP plan and thus controlled in the food process. Additionally, guidance on what considerations and information are required at each level of the decision tree is provided. These decision trees and accompanying information provide a practical and uniform basis for applying Principle #1 and determining which hazards should be addressed in a HACCP plan. The use of risk assessment as a part of risk analysis is also gaining increasing popularity as a means to prioritize food safety issues and policy. Some have proposed the incorporation of risk assessment within the HACCP concept. The relationship of risk analysis to hazard analysis and justification for keeping the two procedures separate is discussed. The methods used in risk assessment and HACCP are at times Similar, but should not be considered the same. Risk assessment and HACCP are two separate functions with two separate scopes, and the incorporation of risk assessment into hazard analysis at this time is counterproductive and should be discouraged. / Ph. D.

There have been several accidents involving autonomous vehicles on public roadways under scenarios that are normally avoidable by competent human drivers. This thesis contains a review of these accidents and their causes as a result of inadequate hazard mitigation. As a solution to this problem, a novel design pattern is proposed. This design pattern was developed from a hazard analysis using Systems Theoretic Process Analysis ( STPA ) methodologies that analyzed the circumstances common to several of these accidents. To demonstrate the effectiveness of the novel design pattern, an example system is constructed and tested in simulation against several accident scenarios similar to the ones studied. The results are then explained to demonstrate the effectiveness of the proposed design pattern. / Thesis / Master of Applied Science (MASc)

Yes / Fault tree analysis is a widely used method of risk assessment in process industries. However, the classical fault tree approach has its own limitations such as the inability to deal with uncertain failure data and to consider statistical dependence among the failure events. In this paper, we propose a comprehensive framework for the risk assessment in process industries under the conditions of uncertainty and statistical dependency of events. The proposed approach makes the use of expert knowledge and fuzzy set theory for handling the uncertainty in the failure data and employs the Bayesian network modeling for capturing dependency among the events and for a robust probabilistic reasoning in the conditions of uncertainty. The effectiveness of the approach was demonstrated by performing risk assessment in an ethylene transportation line unit in an ethylene oxide (EO) production plant.