Landslide Hazard and Climate Change in the Mountain Glacial Environment of Northwest North America

The aim of this thesis was to improve the understanding of the complex interactions between climate change and landslide behavior in the periglacial mountain environment of northwest North America. In particular, this thesis quantified the relationship between climate change (temperature, precipitation, and glacier change) and landslide behavior (magnitude, frequency, and distribution). To achieve this larger aim, four specific research objectives were established: (a) Determine changes in the frequency and distribution of landslides in glacial regions of northwest North America by developing a landslide inventory; (b) Quantify climate change factors, specifically trends in temperature and precipitation; (c) Assess changes in glacier ice area and volume in northwest North America; and (d) Establish a quantitative relationship between climate change, glacier ice loss, and change in landslide hazard. Changes in the frequency and distribution of large (>1Mm3) catastrophic landslides in the mountain glacial environment were determined by developing a regional landslide inventory (Evans and Delaney, Unpublished). The landslide inventory was explored using a magnitude-frequency plot, and results showed that seismically triggered landslides had proportionally fewer large events than non-seismically triggered landslides, highlighting the importance of climate related triggers in large events. Also, the frequency of landslides was determined to be increasing over time, especially at high latitudes (>57 degrees N). Climate change analysis was completed using meteorological station data and trend testing (i.e., Mann-Kendall, Sen’s slope) to develop indices showing temperature and precipitation change. Results show ubiquitous warming (particularly in winter and summer), as well as increasingly dry conditions in Alaska, Yukon, and northern British Columbia, with wetter conditions in central and southern British Columbia. Index results were correlated with landslide mass hypsometrically, showing strong statistical evidence (i.e., Wilcoxon Rank Sum Test) of a connection between increasing temperature and increasing landslide hazard. Precipitation was not correlated with landslide hazard with certainty. Glacier ice loss was assessed using a case study of Mount Meager Volcanic Complex (MMVC), which showed drastic reduction of ice area and volume in response to increased temperature and precipitation. Two major landslides at MMCV (1975/2010) have been found to be triggered by the aforementioned climate factors (increased temperature and precipitation leading to ice loss)