Drivers of earthflow motion revealed by an 80 yr record of displacement from Oak Ridge earthflow, Diablo Range, California, USA

Nereson, A. L.; Finnegan, N. J.

doi:10.1130/b32020.1

Cited by 23 publications

(72 citation statements)

References 32 publications

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“…These large changes in rainfall subsequently caused transitions between dry and wet soil moisture conditions, as quantified by the Palmer Drought Severity Index (PDSI; Figure ). The PDSI (data provided by the WestWide Drought Tracker) is an estimate of relative dryness (negative and positive values correspond to dry and wet conditions, respectively) and serves as a good proxy for the conditions that drive landslide motion because it is based on temperature and precipitation data and accounts for antecedent conditions (Bennett, Roering, et al, ; Nereson & Finnegan, ). The PDSI shows dry conditions between WY2013 and WY2016 and in WY2018 and wet conditions in WY2012 and WY2017 (Figure ).…”

Section: Study Area: Northern California Coast Rangesmentioning

confidence: 99%

“…The most hazardous landslides fail catastrophically and can move kilometers downslope at rates up to tens of meters per second (e.g., Bell, ; Iverson et al, ). Less hazardous, but still destructive, are landslides that move downslope at rates as low as millimeters to meters per year (herein referred to as “slow‐moving landslides”) and can remain active for decades or longer (e.g., Bennett, Roering, et al, ; Bovis & Jones, ; Keefer & Johnson, ; Nereson & Finnegan, ). The persistent and long‐term motion of slow‐moving landslides makes them particularly well suited for investigations that aim to better understand landslide processes.…”

Section: Introductionmentioning

confidence: 99%

“…Recent and ongoing climate shifts in California have already had an impact on the behavior and activity of landslides (Bennett, Roering, et al, ; East et al, ; Handwerger et al, ; Nereson & Finnegan, ). Over the past decade, California has experienced both a historic drought (2012–2016) and the second wettest year on record (2017; Griffin & Anchukaitis, ; Robeson, ; Swain et al, , ).…”

Section: Introductionmentioning

confidence: 99%

“…Bennett, Roering, et al () found that the mean velocity of slow‐moving landslides in the northern California Coast Ranges reached a 70‐year minimum during the recent historic drought. Slow‐moving landslides in the central California Coast Ranges also displayed minimum velocities during the drought (Nereson & Finnegan, ) but displayed high velocities during the extreme wet year of 2017 (Handwerger et al, ; Warrick et al, ). Rapid shifts from dry‐to‐wet extremes in California, similar to the changes in precipitation that occurred between 2012 and 2018, are predicted to increase by 25% to 100% during the 21st century (Swain et al, ).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

et al. 2019

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Episodically to continuously active slow-moving landslides are driven by precipitation.Climate change, which is altering both the frequency and magnitude of precipitation worldwide, is therefore predicted to have a major impact on landslides. Here we examine the behavior of hundreds of slow-moving landslides in northern California in response to large changes in annual precipitation that occurred between 2016 and 2018. We quantify the landslide displacement using repeat-pass radar interferometry and pixel offset tracking techniques on a novel data set from the airborne NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar. We found that 312 landslides were moving due to extreme rainfall during 2017, compared to 119 during 2016, which was the final year of a historic multiyear drought. However, with a return to below to average rainfall in 2018, only 146 landslides remained in motion. The increased number of landslides during 2017 was primarily accommodated by landslides that were smaller than the landslides that remained active between 2016 and 2018. Furthermore, by examining a subset of 51 landslides, we found that 49 had increased velocities during 2017 when compared to 2016. Our results show that slow-moving landslides are sensitive to large changes in annual precipitation, particularly the smaller and thinner landslides that likely experience larger basal pore-water pressure changes. Based on climate model predictions for the next century in California, which include increases in average annual precipitation and increases in the frequency of dry-to-wet extremes, we hypothesize that there will be an overall increase in landslide activity.

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Section: Study Area: Northern California Coast Rangesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

et al. 2019

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“…Average velocity was linked to variability in surface moisture balance and upslope sediment supply (Nereson & Finnegan, 2018). Local bedrock consists of the Mesozoic-early Cenozoic Franciscan Complex (Rubin, 2002).…”

Section: Study Sitementioning

confidence: 99%

Field and Remote‐Sensing Evidence for Hydro‐mechanical Isolation of a Long‐Lived Earthflow in Central California

Nereson

Olivera

Finnegan

2018

Geophysical Research Letters

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Persistent motion of slow-moving landslides has been linked to entrapment of water in slide masses by weak, low-permeability shear zones at their basal and lateral margins. This so-called "bathtub effect" should have remotely sensible effects on soil moisture and vegetation health. Here we assess this effect at a seasonally active earthflow in northern California with analysis of soil properties and nine years (2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) of multispectral satellite imagery. The shear zone has low hydraulic conductivity, and the earthflow shows elevated water content relative to its surroundings. Spectral indices suggest that the earthflow is perennially wetter, and its vegetation thrives for longer into the dry season as a result. The magnitude of the bathtub effect is correlated with cumulative multiyear rainfall, and its surface expression disappears during the driest year of the 2012-2015 drought. These findings demonstrate a new method for identifying and monitoring mechanical and hydrological interactions that enable persistent landslide motion. Plain Language SummaryThe ability of some landslides to move slowly and persistently for many years without accelerating catastrophically may be linked to entrapment of rain water in slide masses by slow-draining boundaries at their sides and bottoms. The existence of this so-called "bathtub effect" can be tested for directly with soil analysis but should also have visible effects on soil moisture and vegetation health that can be measured remotely using satellite imagery. We examined a seasonally active landslide in northern California with slow-draining boundaries and elevated water content relative to its surroundings. Nine years (2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018) of satellite imagery suggest that the earthflow is perennially wetter and its vegetation thrives for longer into the dry season as a result. The magnitude of this effect is correlated with cumulative multiyear rainfall. These findings demonstrate a new method for identifying and monitoring the hydrology and movement of persistent landslides.

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Disproportionate and chronic sediment delivery from a fluvially controlled, deep‐seated landslide in Aotearoa New Zealand

McColl

Holdsworth

Fuller

et al. 2022

Earth Surf Processes Landf

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Past research has highlighted the importance of sediment delivery from multiple‐occurrence regional landslide events triggered by storms or earthquakes. Herein, we examine delivery from a more persistent source of sediment, that of a large, slow‐moving landslide in the soft‐rock hill country of Aotearoa New Zealand. We map and monitor the 80‐ha Rangitikei Landslide from 2015 to 2019 using time‐lapse photography, ground surveys, photogrammetry, and piezometers. We show that the landslide can be divided into several zones with distinctive movement patterns, but all zones respond to river erosion. The fastest zone moves more than 10 m per year in a flow‐like fashion, while other zones move 0.01 m per year via slow sliding. Movement occurs all year round, but is two to three times faster in winter and spring. While rainfall and associated groundwater change are commonly attributed to landslide movement patterns, our data show that river flow correlates closely with the weekly to seasonal variability in movement of the landslide toe. This suggests that fluvial erosion can play an important role in the movement dynamics of highly coupled landslides. We estimate an annual sediment yield to the Rangitikei River of at least 40 000 tonnes, in this first quantification of sediment delivery from an active soft‐rock landslide in Aotearoa. This volume implies 7% of the total catchment suspended sediment yield is derived from 0.03% of the contributing catchment area, demonstrating the disproportionate effect of this (and likely other) deep‐seated landslide(s) as a source of sediment in the Rangitikei catchment. Sediment delivery is more continuous than the episodic supply of multiple‐occurrence regional landslide triggering events, and by delivering mostly fine‐grained sediment, it has a potentially large impact on water quality.

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Drivers of earthflow motion revealed by an 80 yr record of displacement from Oak Ridge earthflow, Diablo Range, California, USA

Cited by 23 publications

References 32 publications

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

Field and Remote‐Sensing Evidence for Hydro‐mechanical Isolation of a Long‐Lived Earthflow in Central California

Disproportionate and chronic sediment delivery from a fluvially controlled, deep‐seated landslide in Aotearoa New Zealand

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