Abstract
Landslides are the most common natural hazard in British Columbia. The province has recorded the largest number of historical landslide fatalities in Canada, and damage to infrastructure comes at a great cost. In order to understand the potential impacts of landslides, radar remote sensing has become a cost-effective method for detecting downslope movements. This study investigates downslope movements in the Southern Interior of British Columbia, Canada, with Sentinel-1 and RADARSAT Constellation Mission (RCM) interferometric synthetic aperture radar (InSAR) data. The 2-dimensional time-series analysis with Sentinel-1 ascending and descending InSAR pairs from October 2017 to June 2021 observed distinct earthflow movements of up to ~15 cm/year in the east–west direction. The Grinder Creek, Red Mountain, Yalakom River, and Retaskit Creek earthflows previously documented are still active, with east–west movements of ~30 cm over the past four years. New RCM data acquired from June 2020 to September 2020 with a 4-day revisit capability were compared to 12-day Sentinel-1 InSAR pairs. The 4-day RCM InSAR pairs at higher spatial resolution showed better performance by detecting relatively small-sized slope movements within a few hundred meters, which were not clearly observed by Sentinel-1. The temporal variabilities observed from the RCM InSAR showed great potential for observing detailed slope movements within a narrower time window.
Highlights
Landslides have had catastrophic impacts, in Canada, in terms of loss of life and damage to infrastructure
Since 1880, there have been at least 356 landslide fatalities in British Columbia (BC) caused by a variety of landslide types, such as rockfalls, rockslides, rock avalanches, debris flows, etc
In November 2020, a massive landslide occurred along the steep mountainous slopes over Elliot Creek in BC, which triggered a tsunami in a glacial lake and a subsequent outburst flood carrying ~7.7 million cubic meters of mud and rock debris into Bute Inlet, reshaping the coastal landscape [7]
Summary
Landslides have had catastrophic impacts, in Canada, in terms of loss of life and damage to infrastructure. Damage to infrastructure has cost millions of Canadian dollars annually in repair and mitigation [2,3]. Porter et al (2019) estimated that, in the Western Canadian Basin alone, costs related to landslide damage or prevention exceed CAD 281–450 million per year [4]. In November 2020, a massive landslide occurred along the steep mountainous slopes over Elliot Creek in BC, which triggered a tsunami in a glacial lake and a subsequent outburst flood carrying ~7.7 million cubic meters of mud and rock debris into Bute Inlet, reshaping the coastal landscape [7]. A bathymetric survey of Harrison Lake reported that ~4 million cubic meters of landslide debris were deposited on the lake floor, which implies the potential
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