Wet- and dry-climate landslides both speed up in wet years
Across California’s huge rainfall gradient, slow landslides still accelerate when local water years are wetter than average.
Source
Landslide Sensitivity and Response to Precipitation Changes in Wet and Dry Climates
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.
What they did
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.
What they found
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.
The limits
What it doesn't show
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.
Key terms
- Slow-moving landslide
- A slope that creeps centimetres per year, detectable as a localized InSAR velocity anomaly.
- Precipitation ratio
- Water-year rainfall divided by the 1990–2019 mean at that landslide.
- Franciscan mélange
- Sheared sedimentary/metasedimentary bedrock that hosts most of California’s slow slides in this inventory.
Flashcards
Research intelligence for this paper
See its role on concept claims, tensions it is part of, placement history, and related discoveries.
Quiz yourself
The California inventory contains how many slow slides?
Common questions
Do dry-climate landslides ignore rainfall?
No. Even southern slides with ~216 mm/yr still slow in drought years and speed up in wet years.
Why similar behaviour despite different climate?
A thin low-conductivity unsaturated zone can saturate after only ~100–200 mm of seasonal rain in both wet and moderate sites.
What ended the 2012–2016 drought hydrologically here?
WY2017, an extremely wet year that reactivated many slides including Mud Creek.
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