Hydrology
Wet- and dry-climate landslides both speed up in wet years
Open access · cc by · source: Europe PMC
Across California’s huge rainfall gradient, slow landslides still accelerate when local water years are wetter than average.
Study at a glance
- Design
- Other — Sentinel-1 InSAR inventory of California slow-moving landslides vs water-year rainfall
- N
- N=247 · 247 active slow-moving landslides; 38-slide subset tracked across a large rainfall gradient
- Population
- Slow-moving landslides in California (mainly Coast Ranges Franciscan mélange)
- Outcome
- Water-year velocity response to wetter vs drier precipitation across climates
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Most slides (230/247) sit in the Coast Ranges; 176 (71%) are in Franciscan mélange. Mean areas are 0.5 km2. Speeds averaged 0.85–9.7 cm/yr. Slides were faster in wet WY2017 and WY2019 and slower in dry WY2016 and WY2018, despite more than a tenfold rainfall range and ~4× thickness range.
Methodology
The authors mapped 247 slow-moving landslides in Sentinel-1 ARIA interferograms (water years 2015–2020), then tracked a 38-slide subset spanning 216–2180 mm/yr mean rain, comparing water-year velocity ratios with precipitation ratios.
Limitations
90 m InSAR misses small slides and heading-parallel motion. One coastal slide sped up in dry WY2018 via wave erosion. The 5-year series cannot separate lithology from climate as the first-order control on speed.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Sentinel-1 is not only ice: 12-day velocities on four Icelandic soft-bed outlets show spring speed-ups ~17 days after melt onset at Skálafellsjökull, while 90 m ARIA interferograms of 247 California landslides (176, 71%, in Franciscan mélange) moved at 0.85–9.7 cm/yr — faster in wet WY2017 and WY2019, slower in dry WY2016 and WY2018, despite a >10× rainfall range. Twelve-day SAR averages smear daily glacier events; InSAR misses heading-parallel motion.
Evidence for the claim as stated.
Sentinel-1 ARIA interferograms (water years 2015–2020) mapped 247 slow-moving landslides; 230/247 sit in the Coast Ranges and 176 (71%) in Franciscan mélange. Mean areas are 0.5 km²; speeds averaged 0.85–9.7 cm/yr. A 38-slide subset spanning 216–2180 mm/yr rain was faster in wet WY2017 and WY2019 and slower in dry WY2016 and WY2018, despite >10× rainfall and ~4× thickness range. One coastal slide sped up in dry WY2018 via wave erosion. This is InSAR displacement, not ice-penetrating radar.
Evidence for the claim as stated.
Ice-penetrating radar, GPR and C-band InSAR are not interchangeable ‘radar observations.’ BedMachine infers thickness from IceBridge plus mass conservation and ship bathymetry; the Antarctic paper images a single buried lake at 400 MHz; the landslide paper measures surface motion at 90 m without seeing the subsurface. Combining 7.42 m of Greenland sea-level potential with 1.5 billion m³ of buried lake water as two ice-sheet radar volumes mixes a continent-scale product with one grounding-zone survey.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Ice-penetrating radar, GPR and C-band InSAR are not interchangeable ‘radar observations.’ BedMachine infers thickness from IceBridge plus mass conservation and ship bathymetry; the Antarctic paper images a single buried lake at 400 MHz; the landslide paper measures surface motion at 90 m without seeing the subsurface. Combining 7.42 m of Greenland sea-level potential with 1.5 billion m³ of buried lake water as two ice-sheet radar volumes mixes a continent-scale product with one grounding-zone survey.
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