Matching Items (2)
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I investigate the Black Canyon City landslide (BCC landslide), a prominent deep-seated landslide located northeast of Black Canyon City, Arizona. Although the landslide does not appear to pose a significant hazard to structures, its prominent features and high topographic relief make it an excellent site to study the geologic setting

I investigate the Black Canyon City landslide (BCC landslide), a prominent deep-seated landslide located northeast of Black Canyon City, Arizona. Although the landslide does not appear to pose a significant hazard to structures, its prominent features and high topographic relief make it an excellent site to study the geologic setting under which such features develop. This study has the potential to contribute toward understanding the landscape evolution in similar geologic and topographic settings, and for characterizing the underlying structural processes of this deep-seated feature. We use field and remotely-based surface geology and geomorphological mapping to characterize the landslide geometry and its surface displacement. We use the Structure from Motion (SfM) method to generate a 0.2 m resolution digital elevation model and rectified ortho-photo imagery from unmanned aerial vehicle (UAV) - and balloon-based images and used them as the base map for our mapping. The ~0.6 km2 landslide is easily identified through remotely-sensed imagery and in the field because of the prominent east-west trending fractures defining its upper extensional portion. The landslide displaces a series of Early and Middle Miocene volcanic and sedimentary rocks. The main head scarp is ~600 m long and oriented E-W with some NW-SE oriented minor scarps. Numerous fractures varying from millimeters to meters in opening were identified throughout the landslide body (mostly with longitudinal orientation). The occurrence of a distinctive layer of dark reddish basalt presents a key displaced marker to estimate the long-term deformation of the slide mass. Using this marker, the total vertical displacement is estimated to be ~70 m, with maximum movement of ~95 m to the SE. This study indicates that the landslide motion is translational with a slight rotational character. We estimate the rate of the slide motion by resurvey of monuments on and off the slide, and examination of disturbed vegetation located along the fractures. The analysis indicates a slow integrated average landslide velocity of 10-60 mm/yr. The slide motion is probably driven during annual wet periods when increased saturation of the slide mass weakens the basal slip surface and the overall mass of the slide is increased. Results from our study suggest that the slide is stable and does not pose significant hazard for the surrounding area given no extreme changes in the environmental condition. Although the landslide is categorized as very slow (according to Cruden and Varnes, 1996), monitoring the landslide is still necessary.
ContributorsHelmi, Hurien (Author) / Arrowsmith, J Ramon (Thesis advisor) / DeVecchio, Duane (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2016
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Description
Coral diseases have become a major vector of change in coral reef physical architecture, functional ecology, and community structure. While the field of spatial community characteristics and coral disease research is growing, major gaps exist in the combination of the two areas of study. Here, I visually assessed over 100,000

Coral diseases have become a major vector of change in coral reef physical architecture, functional ecology, and community structure. While the field of spatial community characteristics and coral disease research is growing, major gaps exist in the combination of the two areas of study. Here, I visually assessed over 100,000 massive Porites corals across 41 reefs in South Kona, Hawaii to investigate the spatial ecology of visually compromised corals. These corals were assessed for seven specific health conditions common to the region: algal infection, pigmentation response, algal overgrowth, Ramicrusta infection, skeletal growth anomalies, Porites trematodiasis, and tissue loss syndrome. Only 6.6% of corals surveyed exhibited a compromised health state and overall condition severity was low; less than 10%. Attributes representing colony assemblage structure showed few observed patterns with the severity and prevalence of these coral health conditions. Additional findings revealed that coral colony traits such as perimeter length had a positive effect on the presence of seven different coral health conditions. Whereas the interaction of both increasing colony surface area and perimeter length was negatively associated the presence of the health conditions. By using global and local spatial statistics, I uncovered trends in reefscape- and colony-level spatial patterns of health-compromised corals. Significant spatial structure existed among colonies based on their health condition severity. However, I found infrequent non-random spatial patterns in most reefs in South Kona.
ContributorsGrady, Bryant William (Author) / Anser, Gregory P (Thesis advisor) / Fotheringham, Stewart (Committee member) / Donovan, Mary (Committee member) / Burns, John (Committee member) / Arizona State University (Publisher)
Created2022