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At least 361 records · Page 20Linked to original sources
USGS2018

Identifying physics‐based thresholds for rainfall‐induced landsliding

Most regional landslide warning systems utilize empirically derived rainfall thresholds that are difficult to improve without recalibration to additional landslide events. To address this limitation, we explored the use of synthetic rainfall to generate thousands of possible storm patterns and coupled them with a physics‐based hydrology and slope stability model for various antecedent soil saturation scenarios to analyze pore‐water pressure and factor of safety metrics. We used these metrics to generate two‐tiered alert thresholds that can be employed to assess shallow landslide potential for any given combination of storm and antecedent wetness. When applied to the San Francisco Bay region (California, USA), the results are consistent with events that caused widespread landsliding. Our deterministic modeling approach, which accounts for plausible ranges in soil hydraulic and mechanical properties, can inform the development of the next generation of warning systems for rainfall‐induced landsliding.

Geophysical Research Letters↗
USGS2020

Detection and assessment of a large and potentially tsunamigenic periglacial landslide in Barry Arm, Alaska

The retreat of glaciers in response to global warming has the potential to trigger landslides in glaciated regions around the globe. Landslides that enter fjords or lakes can cause tsunamis, which endanger people and infrastructure far from the landslide itself. Here we document the ongoing movement of an unstable slope (total volume of 455 million m 3 ) in Barry Arm, a fjord in Prince William Sound, Alaska. The slope moved rapidly between 2010 and 2017, yielding a horizontal displacement of 120 m, which is highly correlated with the rapid retreat and thinning of Barry Glacier. Should the entire unstable slope collapse at once, preliminary tsunami modeling suggests a maximum runup of 300 m near the landslide, which may have devastating impacts on local communities. Our findings highlight the need for interdisciplinary studies of recently deglaciated fjords to refine our understanding of the impact of climate change on landslides and tsunamis.

Alaska↗
USGS2022

Vadose zone thickness limits pore-fluid pressures and acceleration in a large, slow-moving landslide

The rate and timing of hydrologically forced landslides is a complex function of precipitation patterns, material properties, topography, and groundwater hydrology. In the simplest form, however, slopes fail when subsurface pore pressure grows large enough to exceed the Mohr-Coulomb failure criterion. The capacity for pore pressure rise in a landslide is determined in part by the thickness of the unsaturated zone above the water table, which itself is set by weathering patterns that should have predictable patterns across different lithologies. To investigate how this structure affects landslide behavior, we exploit a multi-year record of precipitation, pore pressure, and velocity from Oak Ridge earthflow, a slow-moving landslide set in Franciscan mélange, northern California, USA. In conjunction with electrical resistivity tomography and hydraulic conductivity measurements, these data show that Oak Ridge has a thin weathered profile that is comparable in thickness to other mélange landslides in California. We propose that due to the inherently thin vadose zone, mélange landscapes experience an unusually high water table that frequently brings them close to movement; however, the capacity to increase stress is limited by the small amount of dynamic storage available. Instead, excess pore pressure is shed via springs and saturation overland flow once the water table reaches the surface. Linkages between weathering patterns, hydrology, and deformation can explain behavior patterns exhibited by Franciscan mélange earthflows across a large precipitation gradient.

California↗
USGS2024

A comprehensive assessment of submarine landslides and mass wasting processes offshore southern California

It is critical to characterize submarine landslide hazards near dense coastal populations, especially in areas with active faults, which can trigger slope failure, subsequent tsunamis, and damage seabed infrastructure during earthquake shaking. Offshore southern California, numerous marine geophysical surveys have been conducted over the past decade, and high-resolution bathymetric and subsurface data now cover about 60 percent of the total region between Point Conception and the United States-Mexico border from the California coast out to the base of Patton Escarpment ∼200 km offshore. In a comprehensive compilation and interpretive mapping effort, we find evidence of seafloor failure throughout offshore southern California with nearly 1,500 submarine landslide-related features, including 63 discrete slide deposits with debris and >1,400 slide-related scarps. In our analysis, we highlight new mapping of submarine landslides in Catalina Basin, the Del Mar slide, the San Gabriel slide complex, and the 232 km 2 San Nicolas slide, the largest area of any known submarine landslide mass offshore southern California. Analysis of the spatial distribution of submarine landslide features suggests that most mapped slide features are located relatively near coastal sediment sources, particularly during sea-level lowstand conditions, which underscores the importance of sediment supply and sediment accumulation on low-gradient slopes as failure preconditioning processes. Tectonically driven uplift at shelf edges and along basin flanks is another key preconditioning factor, and our results also suggest that earthquakes along active faults trigger mass wasting, especially for repeated, small-scale failures on tectonically steepened slopes.

California↗
USGS2024

Forecasting inundation of catastrophic landslides from precursory creep

Forecasting landslide inundation upon catastrophic failure is crucial for reducing casualties, yet it remains a long-standing challenge owing to the complex nature of landslides. Recent global studies indicate that catastrophic hillslope failures are commonly preceded by a period of precursory creep, motivating a novel scheme to foresee their hazard. Here, we showcase an approach to hindcast landslide inundation by linking satellite-captured precursory displacements to modeling of consequent granular-fluid flows. We present its application to the 2021 Chunchi, Ecuador landslide, which failed catastrophically and evolved into a mobile debris flow after four months of precursory creep, destroying 68 homes along its lengthy flow path. Underpinned by uncertainty quantification and in situ validations, we highlight the feasibility and potential of forecasting landslide inundation damage using observable precursors. This forecast approach is broadly applicable for flow hazards initiated from geomaterial failures.

Geophysical Research Letters↗
USGS2018

Discussion of “Oso, Washington, landslide of March 22, 2014: Dynamic analysis” by Jordan Aaron, Oldrich Hungr, Timothy D. Stark, and Ahmed K. Baghdady

The original paper under discussion states that it “explains the spectacular mobility of the 2014 Oso landslide.” It addresses this objective by using two versions of the DAN model to compute the distribution of deposits produced by the landslide. The main purpose of this discussion is to demonstrate that the authors’ model is incapable of explaining the Oso landslide’s mobility—even though the model can be tuned to mimic the landslide’s distribution of deposits. An ancillary purpose is to contrast the authors’ model with the Oso landslide model of Iverson et al. (2015) and Iverson and George (2016), and to rebut false statements that the authors made about that model.

Washington↗
USGS1991

Large landslides from oceanic volcanoes

Large landslides are ubiquitous around the submarine flanks of Hawaiian volcanoes, and GLORIA has also revealed large landslides offshore from Tristan da Cunha and El Hierro. On both of the latter islands, steep flanks formerly attributed to tilting or marine erosion have been reinterpreted as landslide headwalls mantled by younger lava flows. These landslides occur in a wide range of settings and probably represent only a small sample from a large population. They may explain the large volumes of archipelagic aprons and the stellate shapes of many oceanic volcanoes. Large landslides and associated tsunamis pose hazards to many islands. -from Authors

Marine Geotechnology↗
USGS2021

High-resolution soil-moisture maps over landslide regions in northern California grassland derived From SAR backscattering coefficients

Slow-moving landslides are destabilized by accumulated precipitation and consequent soil moisture. Yet, the continuous high-resolution soil-moisture measurements needed to aid the understanding of landslide processes are generally absent in steep terrain. Here, we produce soil-moisture time-series maps for a seasonally active grassland landslide in the northern California coast ranges, USA, using backscattering coefficients from NASA's uninhabited aerial vehicle synthetic aperture radar at 6-m resolution. A physically based radar scattering model is used to retrieve the near-surface (5-cm depth) soil moisture for the landslide. Both forward modeling (backscattering estimation) and the retrieval (soil-moisture validation) show good agreement. The root-mean-square errors (RMSE) for vertical transmit vertical receive (VV) and horizontal transmit horizontal receive (HH) polarizations in forward model comparison are 1.93 dB and 1.88 dB, respectively. The soil-moisture retrieval shows unbiased RMSE of 0.054 m 3 /m 3 . Our successful retrieval benefits from the surface and double-bounce scattering, which is common in grasslands. The retrieved maps show saturated wetness conditions within the active landslide boundaries. We also performed sensitivity tests for incidence angle and found that the retrieval is weakly dependent on the angle, especially while using copolarized HH and VV together. Using the two copolarized inputs, the retrieval is also not sensitive to the change of orientation angles of grass cylinders. The physical model inversion presented here can be generally applied for soil-moisture retrieval in areas with the same vegetation cover types in California.

California↗
USGS1987

Real-time landslide warning during heavy rainfall

A real-time system for issuing warnings of landslides during major storms is being developed for the San Francisco Bay region, California. The system is based on empirical and theoretical relations between rainfall and landslide initiation, geologic determination of areas susceptible to landslides, real-time monitoring of a regional network of telemetering rain gages, and National Weather Service precipitation forecasts. This system was used to issue warnings during the storms of 12 to 21 February 1986, which produced 800 millimeters of rainfall in the region. Although analysis after the storms suggests that modifications and additional developments are needed, the system successfully predicted the times of major landslide events. It could be used as a prototype for systems in other landslide-prone regions.

California↗
USGS2003

Landslides and liquefaction triggered by the M 7.9 denali fault earthquake of 3 November 2002

The moment magnitude (M) 7.9 Denali Fault earthquake in Alaska of 3 November 2002 triggered an unusual pattern of landslides and liquefaction effects. The landslides were primarily rock falls and rock slides that ranged in volume from a few cubic meters to the 40 million-cubic-meter rock avalanche that covered much of the McGinnis Glacier. Landslides were concentrated in a narrow zone ???30 km wide that straddled the fault rupture zone over its entire 300 km length. Large rock avalanches all clustered at the western end of the rupture zone where acceleration levels are reported to have been the highest. Liquefaction effects, consisting of sand blows, lateral spreads, and settlement, were widespread within susceptible alluvial deposits extending from Fairbanks eastward several hundred kilometers. The liquefaction effects displayed a pattern of increasing concentration and severity from west to east and extended well beyond the zone of landslides, which is unusual. The contrasting patterns formed by the distributions of landslides and liquefaction effects initially seemed to be inconsistent; however, preliminary analyses of strong-motion records from the earthquake offer a possible explanation for the unusual ground-failure patterns that are related to three subevents that have been discerned from the earthquake records.

GSA Today↗
USGS2009

Submarine landslides of the Southern California Borderland

Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ??2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the mainland slope- Goleta slide in Santa Barbara Channel and Palos Verdes debris avalanche on the San Pedro Escarpment south of Palos Verdes Peninsula. Both of these complexes indicate repeated recurrences of catastrophic slope failure. Recurrence intervals are not well constrained but appear to be in the range of 7500 years for the Goleta slide. The most recent major activity of the Palos Verdes debris avalanche occurred roughly 7500 years ago. A small failure deposit in Santa Barbara Channel, the Gaviota mudflow, was perhaps caused by an 1812 earthquake. Most landslides in this region are probably triggered by earthquakes, although the larger failures were likely conditioned by other factors, such as oversteepening, development of shelf-edge deltas, and high fluid pressures. If a subsequent future landslide were to occur in the area of these large landslide complexes, a tsunami would probably result. Runup distances of 10 m over a 30-km-long stretch of the Santa Barbara coastline are predicted for a recurrence of the Goleta slide, and a runup of 3 m over a comparable stretch of the Los Angeles coastline is modeled for the Palos Verdes debris avalanche. ?? 2009 The Geological Society of America.

Special Paper of the Geological Society of America↗
USGS2006

Coastal landslide material loss rates associated with severe climatic events

Deep-seated landslides along the California coast deliver large amounts of material to the nearshore littoral environment. Landslide movement, a combined result of slope base undercutting by waves and ground saturation, is highly episodic. Movement occurs primarily during periods of high rainfall and large waves, such as those associated with El Nin??o events. This analysis applies remote-sensing techniques to quantify the volumetric net loss rates at three specific landslide sites along the Big Sur coast over three approximately decadal time periods, two of which contained the largest El Nin??o events of the twentieth century. High-resolution historical terrain models were compared in order to provide surface-elevation change data for each landslide complex. To determine the material influx to the littoral system, the landslide complexes were divided into upper and lower slopes, and the surface-elevation change was converted to a volume loss. Some material lost from the upper slope was deposited at the slope base, not into the littoral system. We describe a method to calculate the net loss that omits the deposition volumes from the upper slope. Loss rates were found to be substantially higher during the periods in which El Nin??o events occurred. This is especially true during the period of the 1997-1998 El Nin??o, when 75% of the total material volume was lost, and loss rates were much as sixteen times higher than during non-El Nin??o periods. ?? 2006 Geological Society of America.

Geology↗
USGS1994

Giant Hawaiian landslides

Sixty-eight landslides more than 20 km long are present along a 2200 km segment of the Hawaiian Ridge from near Midway to Hawaii. Some of the landslides exceed 200 km in length and 5000 km3 in volume, ranking them among the largest on Earth. Most of these giant landslides were discovered during a mapping program of the U.S. Hawaiian Exclusive Economic zone from 1986 to 1991 utilizing the GLORIA side-looking sonar mapping system. Two general types of landslides are present: slumps and debris avalanches. Many intermediate forms occur and some debris avalanches form from oversteepened slumps. The slumps are deeply rooted in the volcanoes and may extend back to volcanic rift zones and down to the base of the volcanic pile at about 10 km depth. Debris avalanches are thinner, longer, and move on lower gradients than slumps. Their rapid movement is indicated by the fact that some have moved uphill for tens of kilometers, and are believed to have produced major tsunamis. The debris avalanches left large amphitheaters at their heads and produce broad hummocky distals lobes at their toes. Commonly, major canyons have incised the amphitheaters. Giant landslides have recently been discovered on many other marine volcanoes where they also can be related to volcanic structure and eruptive activity.

Book chapter↗
USGS2016

Modelling landslide liquefaction, mobility bifurcation and the dynamics of the 2014 Oso disaster

Some landslides move slowly or intermittently downslope, but others liquefy during the early stages of motion, leading to runaway acceleration and high-speed runout across low-relief terrain. Mechanisms responsible for this disparate behaviour are represented in a two-phase, depth-integrated, landslide dynamics model that melds principles from soil mechanics, granular mechanics and fluid mechanics. The model assumes that gradually increasing pore-water pressure causes slope failure to nucleate at the weakest point on a basal slip surface in a statically balanced mass. Failure then spreads to adjacent regions as a result of momentum exchange. Liquefaction is contingent on pore-pressure feedback that depends on the initial soil state. The importance of this feedback is illustrated by using the model to study the dynamics of a disastrous landslide that occurred near Oso, Washington, USA, on 22 March 2014. Alternative simulations of the event reveal the pronounced effects of a landslide mobility bifurcation that occurs if the initial void ratio of water-saturated soil equals the lithostatic, critical-state void ratio. They also show that the tendency for bifurcation increases as the soil permeability decreases. The bifurcation implies that it can be difficult to discriminate conditions that favour slow landsliding from those that favour liquefaction and long runout.

Washington↗
USGS2012

Extraordinary distance limits of landslides triggered by the 2011 Mineral, Virginia, earthquake

The 23 August 2011 Mineral, Virginia, earthquake (M w 5.8) was the largest to strike the eastern U.S. since 1897 and was felt over an extraordinarily large area. Although no large landslides occurred, the shaking did trigger many rock and soil falls from steep river banks and natural cliffs in the epicentral area and from steep road cuts along, and northwest of, the Blue Ridge Parkway. We mapped the occurrence of rock falls to determine distance limits that could be compared with those from other documented earthquakes. Studies of previous earthquakes indicated a maximum epicentral distance limit for landsliding of ~60 km for an M 5.8 earthquake; the maximum distance limit for the 2011 earthquake was 245 km, the largest exceedance of the historical limit ever recorded. Likewise, the previous maximum area affected by landslides for this magnitude was 1500 km 2 ; the area affected by landslides in the 2011 earthquake was 33,400 km 2 . These observations provide physical evidence that attenuation of strong shaking for eastern U.S. earthquakes is significantly lower than for plate‐boundary earthquakes. Also, distance limits parallel to the regional structural trend are greater than those that transect the structure, which suggests anisotropic attenuation related to the regional geologic structure. Peak ground acceleration (PGA) at the landslide distance limits is estimated to have been about 0.02–0.04g.

Virginia↗
USGS2010

Analysis of elevation changes detected from multi-temporal LiDAR surveys in forested landslide terrain in western Oregon

We examined elevation changes detected from two successive sets of Light Detection and Ranging (LiDAR) data in the northern Coast Range of Oregon. The first set of LiDAR data was acquired during leafon conditions and the second set during leaf-off conditions. We were able to successfully identify and map active landslides using a differential digital elevation model (DEM) created from the two LiDAR data sets, but this required the use of thresholds (0.50 and 0.75 m) to remove noise from the differential elevation data, visual pattern recognition of landslideinduced elevation changes, and supplemental QuickBird satellite imagery. After mapping, we field-verified 88 percent of the landslides that we had mapped with high confidence, but we could not detect active landslides with elevation changes of less than 0.50 m. Volumetric calculations showed that a total of about 18,100 m3 of material was missing from landslide areas, probably as a result of systematic negative elevation errors in the differential DEM and as a result of removal of material by erosion and transport. We also examined the accuracies of 285 leaf-off LiDAR elevations at four landslide sites using Global Positioning System and total station surveys. A comparison of LiDAR and survey data indicated an overall root mean square error of 0.50 m, a maximum error of 2.21 m, and a systematic error of 0.09 m. LiDAR ground-point densities were lowest in areas with young conifer forests and deciduous vegetation, which resulted in extensive interpolations of elevations in the leaf-on, bare-earth DEM. For optimal use of multi-temporal LiDAR data in forested areas, we recommend that all data sets be flown during leaf-off seasons.

Environmental & Engineering Geoscience↗
USGS2010

Location of photographs showing landslide features in the Little North Santiam River Basin, Oregon

Data points represent locations of photographs taken of landslides in the Little North Santiam River Basin, Oregon. Photos were taken in spring of 2010 during field verification of landslide locations (deposits previously mapped using LiDAR-derived imagery). The photographs depict various landslide features, such as scarps, pistol-butt trees, or colluvium deposits. This work was completed as part of the Master's thesis "Turbidity Monitoring and LiDAR Imagery Indicate Landslides are Primary Source of Suspended-Sediment Load in the Little North Santiam River Basin, Oregon, Winter 2009-2010" by Steven Sobieszczyk, Portland State University and U.S. Geological Survey. Data layers in this geodatabase include: landslide deposit boundaries (Deposits); field-verfied location imagery (Photos); head scarp or scarp flanks (Scarp_Flanks); and secondary scarp features (Scarps).The geodatabase template was developed by the Oregon Department of Geology and Mineral Industries (Burns and Madin, 2009).

Oregon↗
USGS2012

Real-time monitoring of landslides

Landslides cause fatalities and property damage throughout the Nation. To reduce the impact from hazardous landslides, the U.S. Geological Survey develops and uses real-time and near-real-time landslide monitoring systems. Monitoring can detect when hillslopes are primed for sliding and can provide early indications of rapid, catastrophic movement. Continuous information from up-to-the-minute or real-time monitoring provides prompt notification of landslide activity, advances our understanding of landslide behavior, and enables more effective engineering and planning efforts.

Fact Sheet↗