Tectonic and sedimentary processes of the southeast Alaska margin

Strike-slip tectonics dominate the southeast Alaska margin. The Queen Charlotte-Fairweather Fault transform system extends ~1200 km from southern Canada north to Yakutat Bay, Alaska, accommodating nearly 4.5 cm/yr of dextral offset between the Pacific and North American plates. This dissertation aims to better characterize the transform plate boundary by examining the accommodation of oblique transpression, crustal structure, seismogenic faults, and tectonic influence on regional sedimentary processes. We address fundamental tectonic questions utilizing a suite of geophysical data including multichannel seismic (MCS) reflection, bathymetry, magnetics, gravity, and earthquake data. A 2011 MCS survey reveals subsurface channel deposits related to the development of the deep-sea Baranof sedimentary fan in the Gulf of Alaska. We find that Baranof Fan channels have avulsed consistently southward, affected by the changing position of channel heads relative to sediment sources along the shelf edge due to strike-slip motion along the Queen Charlotte Fault (QCF). Baranof Fan sediments sit atop a flexural depression in the Pacific crust near the QCF, which developed between ~6 Ma and ~2 Ma. We interpret the flexure to be an artifact of oblique convergence along the southern QCF, preserved by sedimentary loading in part from the Baranof Fan. ~150 km of the QCF near the Pacific flexural depression ruptured in January 2013, producing a M [subscript]w 7.5 earthquake near Craig, Alaska. A tomographic inversion of Craig aftershock data reveals a low velocity zone on the Pacific side of the plate boundary at seismogenic depths, which may indicate the contrast of a warm, young Pacific crust along the older, colder North American crust. These results have relevance for rupture directionality and future seismic hazard along the QCF. Finally, we revisit seismic hazard associated with the 10 September 1899 Mw 8.2 earthquake at the northern termination of the transform system near Yakutat Bay, Alaska. We quantify uncertainty on coseismic uplift measurements and integrate various geophysical data, including a 2012 MCS survey, to provide an updated fault map and tectonic model of the Yakutat Bay region. Our results support a subduction-related rupture of the 10 September event with limited slip along the transpressive termination of the Fairweather Fault.Geological Science

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

The Queen Charlotte fault (QCF) is a dextral transform system located offshore of southeastern Alaska and western Canada, accommodating similar to 4.4 cm/yr of relative motion between the Pacific and North American plates. Oblique convergence along the fault increases southward, and how this convergence is accommodated is still debated. Using seismic reflection data, we interpret offshore basement structure, faulting, and stratigraphy to provide a geological context for two recent earthquakes, an M-w 7.5 strike-slip event near Craig, Alaska, and an M-w 7.8 thrust event near Haida Gwaii, Canada. We map downwarped Pacific oceanic crust near 54 degrees N, between the two rupture zones. Observed downwarping decreases north and south of 54 degrees N, parallel to the strike of the QCF. Bending of the Pacific plate here may have initiated with increased convergence rates due to a plate motion change at similar to 6 Ma. Tectonic reconstruction implies convergence-driven Pacific plate flexure, beginning at 6 Ma south of a 10 degrees bend the QCF (which is currently at 53.2 degrees N) and lasting until the plate translated past the bend by similar to 2 Ma. Normal-faulted approximately late Miocene sediment above the deep flexural depression at 54 degrees N, topped by relatively undeformed Pleistocene and younger sediment, supports this model. Aftershocks of the Haida Gwaii event indicate a normal-faulting stress regime, suggesting present-day plate flexure and underthrusting, which is also consistent with reconstruction of past conditions. We thus favor a Pacific plate underthrusting model to initiate flexure and accommodation space for sediment loading. In addition, mapped structures indicate two possible fault segment boundaries along the QCF at 53.2 degrees N and at 56 degrees N.USGS Earthquake Hazards External Grants ProgramNational Earthquake Hazards Reduction ProgramUTIG Ewing/Worzel FellowshipInstitute for Geophysic

Prevalence and Severity of Alcohol and Cannabis Use Across the Urban‐Rural Continuum in the Michigan National Guard

PurposeThe National Guard provides critical support both domestically and abroad with soldiers dispersed throughout America and spanning the urban‐rural continuum. To determine if location‐specific interventions may be needed, we compared the prevalence and severity of cannabis and alcohol use among National Guard members across localities.MethodsMichigan National Guard members were enrolled (N = 2,746) during drill weekends as part of a larger randomized behavioral trial. Cannabis (ASSIST; prevalence = 5%) and alcohol use (AUDIT; prevalence = 82%) were compared using hurdle regression models across locality status after adjusting for covariates.FindingsPrevalence of cannabis and alcohol use was predicted by locality (adjusted odds ratio [AOR] = 0.913, 95% CI: 0.838‐0.986, P = .029; AOR = 0.963, 95% CI: 0.929‐0.998, P = .038, respectively), with more use in urban localities. Neither severity of cannabis nor alcohol use was predicted by locality status.ConclusionsPrevalence of cannabis and alcohol use in the National Guard is differentially elevated across localities with higher prevalence in more central, densely populated areas. Findings may inform future work considering accessibility and utilization of prevention and treatment services for Guard members across the urban‐rural continuum.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154619/1/jrh12412.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154619/2/jrh12412_am.pd

Increased emergency department use by adolescents and young adults with eating disorders

Objective: This study describes patterns of emergency department (ED) utilization by patients who screen positive for eating disorders. Method: ED patients aged 14–20 years ( n = 1,920) completed a computerized questionnaire. The analyses compared the rates of ED use between patients who screened positive for an eating disorder and those who did not and examined the reasons for ED use amongst patients with eating disorders. Results: ED patients who screened positive for eating disorders were significantly more likely to have previously visited the ED and, on average, utilized the ED at a rate 1.6 times higher than patients who screen negative for eating disorders. The most common chief complaints among patients who screen positive for eating disorders were abdominal pain and other gastrointestinal‐related problems. Discussion: Patients with eating disorders utilize the ED more frequently than those without and commonly present for complaints seemingly unrelated to their eating disorder. © 2012 by Wiley Periodicals, Inc. (Int J Eat Disord 2013)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97531/1/22070_ftp.pd

Determinants of early alcohol and drug use among young women in alcoholism treatment

Substance abuse experimentation may be one of several types of problem behaviors. Data from 99 Caucasian women interviewed in alcoholism treatment (19-29 years old) were used to test a developmental model of substance experimentation. Responders were classified into three groups based on their use prior to age 15: nonusers, users of alcohol only, and users of alcohol and other drugs. Family history of alcoholism was not related to childhood anxiety and impulse control problems. Childhood anxiety and impulse control problems predicted adolescent emotional and impulse control problems but did not differentiate early experimenters. Whereas adolescent emotional problems were not related to early experimentation, early drug and alcohol users were significantly more likely to have engaged in other impulsive behaviors (e.g., running away from home, trouble with school authorities) than were nonusers or users of alcohol only. Alcoholism prevention programs, therefore, would do well to target youth who exhibit acting-out behaviors as a high-risk group for early alcohol and drug use.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31925/1/0000878.pd

The prevalence and correlates of eating disorders in adult emergency department patients

ObjectiveThis study describes the prevalence of eating disorders among adult patients who present to the emergency department for medical care and examines the relationship between eating disorders, depression, and substance use disorders.MethodEmergency department patients aged 21-65-years (n = 1,795) completed a computerized questionnaire that included validated screening tools for eating disorders, risky drinking behavior, other substance use, and depression. Analyses were conducted comparing individuals who screened positive for an eating disorder with those who did not based on demographics (gender, age, race, income, education), body mass index (BMI), risky drinking behavior, other substance use, and depression.ResultsNearly 16% (15.9%) of all patients screened positive for an eating disorder regardless of their reason for presenting to the emergency department. Patients who screened positive for an eating disorder were significantly more likely to have a BMI->-30 (odds ratio [OR] = 2.68, confidence interval [CI] = 1.98, 3.62, p-<-.001), to also screen positive for depression (OR = 3.19, CI = 2.28, 4.47, p-<-.001) and to be female (OR = 2.37, CI = 1.76, 3.19, p-<-.001). No differences in the prevalence of positive screens for eating disorders were seen across age or racial groups, level of education or income, or for any of the included substance use variables.DiscussionEating disorders are common among adult emergency department patients and are associated with high rates of comorbid depression and higher BMI. Given the significant morbidity and mortality associated with eating disorders, targeted screening may be warranted in the emergency department setting.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152020/1/eat23140_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152020/2/eat23140.pd

Examining Measurement Reactivity in Daily Diary Data On Substance Use: Results From a Randomized Experiment

The debate about whether measurement reactivity exists in daily diary research on substance use is still unsettled due to the issues of study design and statistical methodology. This study proposes a time-varying effect model (TVEM) that characterizes the trajectory of substance use behaviors with nonparametric functions determined by the data rather than imposes presumed parametric functions. It also allows researchers to investigate the effect of measurement reactivity on not only the likelihood of using substances but also the amount of substance use. The TVEM was applied to analyze diary data on alcohol and marijuana use collected from an experiment, which randomized 307 participants in Michigan into daily and weekly assessment schedules during 2014-2016. This study found short-term measurement reactivity on alcohol use, but did not find a significant reactivity effect on marijuana use. The daily group had smaller odds of abstinence from drinking but lower expected drinking quantity in the first week of assessment, which dissipated by the second week. The results indicate that although daily self-monitoring could have short-term reactivity on substance use behaviors that tend to fluctuate across days, such as alcohol use, it does not affect substance use behaviors that are quite consistent, such as marijuana use. Our findings imply that although daily monitoring of drinking may motivate people to reduce the quantity consumed once they start to drink, it may also arouse their desire to start drinking. Yet, both effects tend to last only one week, as participants accommodate to the monitoring by the second week

The role of attributions in abstinence, lapse, and relapse following substance abuse treatment

This study examined the role of attributions in the lapse and relapse process following substance abuse treatment. According to Marlatt and Gordon's theoretical framework, attributions made after a lapse (e.g., the Abstinence Violation Effect [AVE]) determine whether it progresses to a relapse. Also examined were the attributions of recovering drug users who were tempted but remained abstinent (never lapsed). Ninety-seven participants were recruited from an inpatient treatment center for substance abuse and completed an interview 6 months after leaving treatment. Findings partially confirmed predictions made by the AVE. Predictions made by the AVE were not supported in that lapsers and relapsers were similar regarding their internal/external attributions following a return to drug use; predictions were supported as relapsers made more stable and global attributions as compared to lapsers. Also as predicted, abstainers made more internal, stable, and global attributions regarding their abstinence (as compared to lapsers following their slip). Abstainers' attributions for their success in remaining abstinent tended to be similar to the attributions made by relapsers for their failure to remain abstinent (i.e., for their relapse). Combined, these findings highlight the complexity of the attributional process in early recovery from substance abuse. Clinical and research implications of the findings are discussed in relation to substance abuse relapse prevention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31616/1/0000547.pd

A brief tailored family-centered seat belt intervention for hospitalized trauma patients

Among children 5-19 years, the commonest cause of unintentional injury-related death is being an occupant/driver in a motor vehicle crash (MVC). In 2006 in the United States, there were 568,188 injuries among children (0-18) due to MVC. Of these, 38,039 were severe enough to require hospitalization and there were 6,781 deaths. Seat belts and appropriate child restraints reduce the morbidity and mortality from MVC. Yet studies have shown that less than 50% of children hospitalized from a MVC were restrained at the time of the crash. In 2007, a statewide direct observation survey reported 93.7% of Michigan motorists wore their seat belts in the front seat. In 2007, at the University of Michigan CS Mott Hospital, 120 children were hospitalized due to MVC and only 64% were restrained. The unrestrained children suffered the most severe injuries and had the greater morbidity. A prime factor that influences whether a child uses a safety device is whether a parent uses a seat belt. In focus groups, teens said they used seat belts because of how they were raised. In a prior study, we compared safety attitudes and practices with 800 grade 4-6 children paired with their parents. Matched analysis demonstrated that parents who always wear a seat belt are more likely to have children who sit in the back seat and wear a seat belt (73% vs. 27%, p<0.05). This suggests that the parent/child non-seat belt/restraint users are an ideal target for an intervention. Our hypothesis for this study was that both parents and children are equally important in modifying pediatric safety practices. The specific aim of this study was to develop and test in a randomized controlled study a brief family- centered “seat belt intervention.U.S. Department of Transportation/NHTSA, Office of Behavioral Safety Research (OBSR)http://deepblue.lib.umich.edu/bitstream/2027.42/86092/1/102760.pd

The Relationship Between Cumulative Risk and Promotive Factors and Violent Behavior Among Urban Adolescents

Resiliency theory posits that some youth exposed to risk factors do not develop negative behaviors due to the influence of promotive factors. This study examines the effects of cumulative risk and promotive factors on adolescent violent behavior and tests two models of resilience—the compensatory model and the protective model—in a sample of adolescent patients (14–18 years old; n = 726) presenting to an urban emergency department who report violent behavior. Cumulative measures of risk and promotive factors consist of individual characteristics and peer, family, and community influences. Hierarchical multiple regression was used to test the two models of resilience (using cumulative measures of risk and promotive factors) for violent behavior within a sample of youth reporting violent behavior. Higher cumulative risk was associated with higher levels of violent behavior. Higher levels of promotive factors were associated with lower levels of violent behavior and moderated the association between risk and violent behaviors. Our results support the risk‐protective model of resiliency and suggest that promotive factors can help reduce the burden of cumulative risk for youth violence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117187/1/ajcp9541.pd