•  
  •  
 

Subjects

Oregon Coast Range (Or.) -- Geomorphology, Landslides -- Oregon -- Oregon Coast Range, Oregon Coast Range (Or.) -- Hydrology, Landslide hazard analysis

Abstract

Landslides can occur in many locations across the world and have the potential to be extremely destructive if failures occur near populated areas. Failures are most likely to occur on slopes that have already experienced numerous failures. This means they are a considerable hazard, and the risk involved with building in areas that have previously experienced landslides should be adequately understood. This study examines the reactivation potential of a deep-seated landslide located in the Oregon Coast Range. The analysis of this landslide included creating a map of the surface morphology and computing the factor of safety for the deposit using the Swedish method of slices. The surface morphology map determined that the landslide is relatively young and currently inactive. The factor of safety was computed for two conditions—the base conditions in the field and an estimated fully saturated condition. The factor of safety determined for both conditions was used to calculate the critical acceleration needed to induce failure. This calculation was completed using Newmark’s analysis of a sliding block. The slope is stable in base conditions with a factor of safety of 2.22 and it would take a critical acceleration of 22% of g to cause slope failure (Table 4). This ground acceleration can be related to a Modified Mercalli Intensity of seven or greater. For saturated conditions, the slope is also stable, but a smaller critical acceleration will produce failure, namely 7.7% of g, which is an earthquake of Modified Mercalli intensity of five or above (Table 4).

Thanks go to Dr. Adam Booth for his guidance during this project, my fellow peers in the course that aided in field data collections, and Genna McLeod for helping edit the article for publication.

DOI

10.15760/anthos.2020.9.1.7

Persistent Identifier

https://archives.pdx.edu/ds/psu/32841

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.