Offshore landslide hazard curves from mapped landslide size distributions

Journal of Geophysical Research B: Solid Earth
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Abstract

We present a method to calculate landslide hazard curves along offshore margins based on size distributions of submarine landslides. The method analyzes ten different continental margins, that were mapped by high-resolution multibeam sonar with landslide scar areas measured by a consistent GIS procedure. Statistical tests of several different probability distribution models indicate that the lognormal model is most appropriate for these siliciclastic environments, consistent with an earlier study of the U.S. Atlantic margin [Chaytor et al., 2009]. Parameter estimation is performed using the maximum likelihood technique and confidence intervals are determined using likelihood profiles. Pairwise comparison of size distributions for the ten margins indicates that the U.S. Atlantic and Queen Charlotte margins are different than most other margins. These margins represent end members, with the U.S. Atlantic margin having the highest mean scar area and the Queen Charlotte margin, the lowest. We demonstrate that empirical, offshore landslide hazard curves can be developed from the landslide size distributions, if the duration of mapped landslide activity is known. This study indicates that the shape parameter of the size distribution is similar among all ten margins and thus the shape of the hazard curves is also similar. Significant differences in hazard curves among the margins are therefore related to differences in mean sizes and, potentially, differences in the duration of landslide activity.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Offshore landslide hazard curves from mapped landslide size distributions
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/2018JB017236
Volume 124
Issue 4
Year Published 2019
Language English
Publisher American Geophysical Union
Contributing office(s) Pacific Coastal and Marine Science Center
Description 15 p.
First page 3320
Last page 3334