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.
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.
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.
Inspect source passages
Wet- and dry-climate landslides both speed up in wet years
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Where are most of them?
The active landslides are distributed throughout the mountainous regions in western California, with the vast majority (230 of 247) in the Coast Ranges, and they spanned nearly the entire latitudinal extent of the state.
What first-order behaviours are shared across the rainfall gradient?
these landslides exhibit similar first order behaviors including (a) seasonal and annual changes in displacement corresponding to local changes in rainfall, and (b) sensitivity to seasonal, annual, and multi‐annual changes in rainfall.
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.
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