Bedrock landsliding, including the formation of landslide dams, is a predominant geomorphic process in steep landscapes. Clarifying the importance of hydrologic and seismic mechanisms for triggering deep‐seated landslides remains an ongoing effort, and formulation of geomorphic metrics that predict dam preservation is crucial for quantifying secondary landslide hazards. Here, we identify >200 landslide‐dammed lakes in western Oregon and utilize dendrochronology and enhanced14C dating (“wiggle matching”) of “ghost forests” to establish slope failure timing at 20 sites. Our dated landslide dataset reveals bedrock landsliding has been common since the last Cascadia Subduction Zone earthquake in January 1700 AD. Our study does not reveal landslides that date to 1700 AD. Rather, we observe temporal clustering of
- Award ID(s):
- 1719496
- NSF-PAR ID:
- 10149620
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Date Published:
- Journal Name:
- Bulletin of the New Zealand Society for Earthquake Engineering
- Volume:
- 50
- Issue:
- 2
- ISSN:
- 1174-9857
- Page Range / eLocation ID:
- 106 to 116
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract at least four landslides in the winter of 1889/1890 AD, coincident with a series of atmospheric rivers that generated one of the largest regionally recorded floods. We use topographic and field analyses to assess the relation between dam preservation and topographic characteristics of the impounded valleys. In contrast to previous studies, we do not observe systematic scaling between dam size and upstream drainage area, though dam stability indices for our sites correspond with “stable” dams elsewhere. Notably, we observe that dams are preferentially preserved at drainage areas of ∼1.5 to 13 km2and valley widths of ∼25 to 80 m, which may reflect the reduced downstream influence of debris flows and the accumulation of mature conifer trees upstream from landslide‐dammed lake outlets. We suggest that wood accumulation upstream of landslide dams tempers large stream discharges, thus inhibiting dam incision. -
Following the November 14 2016 Mw7.8 Kaikoura earthquake, field expeditions were undertaken using Unmanned Aerial Vehicles (UAVs) to map 25 sites of scientific interest with a plan area of 7.2 km2. A total of 23,172 images collected by the UAVs were used as input in Structure-from-Motion (SfM) to create 3D models of the target areas with a focus on landslides and fault rupture. Two sites are presented in more detail as examples of the data generated; a section of the Kekerengu fault that ruptured during the earthquake, and the Limestone Hills landslide. The sites were mapped at high resolution with ground sampling distance that varied from 0.5 to 7.0 cm/pixel. The developed SfM models were compared to 1-m aerial LiDAR data and the results were found to be comparable. However, the higher resolution of the SfM digital surface model (DSM), paired with the imagery facilitated more detailed interpretations, highlighting the usefulness of the UAV-enabled SfM as a mobile and effective technique for documenting perishable post-earthquake reconnaissance data.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5459/bnzsee.50.2.106-116
