Major: Geology, minor in Meteorology
Academic Affiliation: University Of Puerto Rico, Mayagüez Campus
Ashlyann was born in Manati, Puerto Rico and raise in the town of Arecibo. Always having a sense that she would study science, her initial interest in meteorology led her to apply to the field of geology at the University of Puerto Rico Mayagüez. She is interested in studying how to help communities prepare for and deal with natural disasters. When not studying, she loves to dance, listen to music, and spend time with family and friends.
2012- Controls on landslides in a low relief topography, New Jersey
Every year, landslides kill and injure people and damage homes and structures around the world. The U.S Geological Survey recently developed a prototype landslide hazard map for the conterminous United States. One of the questions to answer when making such a map is how to delineate areas of negligible hazard, particularly in areas of low topographic relief.
The purpose of this research is to identify which areas in New Jersey, a low relief area, are prone to landslides and which factors distinguish landslide-prone areas.
Landslide point locations were obtained from a database of 181 historical landslides (1782 to 2010) compiled by the New Jersey Geological Survey. Of those 181 landslides, 17 caused 68 fatalities and 53 injuries. Our analysis of the database and precipitation records show that the majority of the landslides (54%) in this area are triggered by heavy rain.
New Jersey is underlain by clastic sedimentary, nonclastic sedimentary, igneous intrusive, igneous extrusive, and metamorphic rocks. The majority of landslides occur in the areas dominated by igneous and metamorphic rocks, with the highest incidence of landslides occurring in the igneous rocks.
We used GIS to overlay landslide point locations on maps of lithology, local relief, and slope. A majority (53%) of the landslides occurred on slopes of 10° or less. We created buffer zones of 90m, 240m, and 480m around the landslide locations to find the steepest slope bordering each landslide. The results confirmed that the landslides did occur in areas of low relief. An in-depth study of the database revealed that human activity such as construction, mining, and quarrying contributed to 32% of landslides on gentle slopes (≤10°), suggesting that human activity was a significant trigger. Higher resolution (1-3 m) elevation data are needed to adequately identify landslide-prone slopes in low-relief areas such as New Jersey.
2014- A detailed study of debris flow source areas in the northern Colorado Front Range
Nearly continuous, heavy rainfall occurred during 9-13 September 2013 causing flooding and widespread landslides and debris flows in the northern Colorado Front Range. Whereas many recent studies have identified erosion as the most common process leading to debris flows in the mountains of Colorado, nearly all of the debris flows mapped in this event began as small, shallow landslides. We mapped the boundaries of 415 September 2013 debris flows in the Eldorado Springs and Boulder 7.5-minute quadrangles using 0.5-m-resolution satellite imagery. We characterized the landslide source areas of six debris flows in the field as part of an effort to identify what factors controlled their locations. Four were on a dip slope in sedimentary rocks in the Pinebrook Hills area, near Boulder, and the other two were in granitic rocks near Gross Reservoir. Although we observed no obvious geomorphic differences between the source areas and surrounding non-landslide areas, we noted several characteristics that the source areas all had in common. Slopes of the source areas ranged from 28° to 35° and most occurred on planar or slightly concave slopes that were vegetated with grass, small shrubs, and sparse trees. The source areas were shallow, irregularly shaped, and elongated downslope: widths ranged from 4 to 9 m, lengths from 6 to 40 m and depths ranged from 0.7 to 1.2 m. Colluvium was the source material for all of the debris flows and bedrock was exposed in the basal surface of all of the source areas. We observed no evidence for concentrated surface runoff upslope from the sources. Local curvature and roughness of bedrock and surface topography, and depth distribution and heterogeneity of the colluvium appear to have controlled the specific locations of these shallow debris-flow source areas. The observed distribution and characteristics of the source areas help guide ongoing efforts to model initiation of the debris flows.