scholarly journals A Pilot Experiment on Infrasonic Lahar Detection at Mount Adams, Cascades: Ambient Infrasound and Wind-Noise Characterization at a Quiescent Stratovolcano

2021 ◽  
Author(s):  
Richard W. Sanderson ◽  
Robin S. Matoza ◽  
Rachel M. Haymon ◽  
Jamison H. Steidl
Keyword(s):  
Debris Flows ◽  
Mass Movement ◽  
Hydrothermal Activity ◽  
Mass Wasting ◽  
Wind Noise ◽  
Pilot Experiment ◽  
Flow Speeds ◽  
Mount Adams ◽  
Downstream Communities ◽  
Noisy Background

Abstract Erosion, hydrothermal activity, and magmatism at volcanoes can cause large and unexpected mass wasting events. Large fluidized debris flows have occurred within the past 6000 yr at Mount Adams, Washington, and present a hazard to communities downstream. In August 2017, we began a pilot experiment to investigate the potential of infrasound arrays for detecting and tracking debris flows at Mount Adams. We deployed a telemetered four-element infrasound array (BEAR, 85 m aperture), ~11 km from a geologically unstable area where mass wasting has repeatedly originated. We present a preliminary analysis of BEAR data, representing a survey of the ambient infrasound and noise environment at this quiescent stratovolcano. Array processing reveals near continuous and persistent infrasound signals arriving from the direction of Mount Adams, which we hypothesize are fluvial sounds from the steep drainages on the southwest flank. We interpret observed fluctuations in the detectability of these signals as resulting from a combination of (1) wind-noise variations at the array, (2) changes in local infrasound propagation conditions associated with atmospheric boundary layer variability, and (3) changing water flow speeds and volumes in the channels due to freezing, thawing, and precipitation events. Suspected mass movement events during the study period are small (volumes <105  m3 and durations <2 min), with one of five visually confirmed events detected infrasonically at BEAR. We locate this small event, which satellite imagery suggests was a glacial avalanche, using three additional temporary arrays operating for five days in August 2018. Events large enough to threaten downstream communities would likely produce stronger infrasonic signals detectable at BEAR. In complement to recent literature demonstrating the potential for infrasonic detection of volcano mass movements (Allstadt et al., 2018), this study highlights the practical and computational challenges involved in identifying signals of interest in the expected noisy background environment of volcanic topography and drainages.

scholarly journals Influence of biopolymers on the rheological properties of seafloor sediments and the runout behavior of submarine debris flows

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jun Kameda ◽  
Hamada Yohei
Keyword(s):  
Rheological Properties ◽  
Debris Flows ◽  
Extracellular Polymeric Substances ◽  
Flow Behavior ◽  
Mass Movement ◽  
Rheological Parameters ◽  
Natural Environments ◽  
Natural Systems ◽  
Chemical Conditions ◽  
Seafloor Sediments

AbstractSubmarine debris flows are mass movement processes on the seafloor, and are geohazards for seafloor infrastructure such as pipelines, communication cables, and submarine structures. Understanding the generation and run-out behavior of submarine debris flows is thus critical for assessing the risk of such geohazards. The rheological properties of seafloor sediments are governed by factors including sediment composition, grain size, water content, and physico-chemical conditions. In addition, extracellular polymeric substances (EPS) generated by microorganisms can affect rheological properties in natural systems. Here we show that a small quantity of EPS (~ 0.1 wt%) can potentially increase slope stability and decrease the mobility of submarine debris flows by increasing the internal cohesion of seafloor sediment. Our experiments demonstrated that the flow behavior of sediment suspensions mixed with an analogue material of EPS (xanthan gum) can be described by a Herschel–Bulkley model, with the rheological parameters being modified progressively, but not monotonously, with increasing EPS content. Numerical modeling of debris flows demonstrated that the run-out distance markedly decreases if even 0.1 wt% of EPS is added. The addition of EPS can also enhance the resistivity of sediment to fluidization triggered by cyclic loading, by means of formation of an EPS network that binds sediment particles. These findings suggest that the presence of EPS in natural environments reduces the likelihood of submarine geohazards.

scholarly journals Landslides after wildfire: initiation, magnitude, and mobility

Landslides ◽  
2020 ◽  
Vol 17 (11) ◽  
pp. 2631-2641
Author(s):  
Francis K. Rengers ◽  
Luke A. McGuire ◽  
Nina S. Oakley ◽  
Jason W. Kean ◽  
Dennis M. Staley ◽  
...  
Keyword(s):  
Debris Flows ◽  
Rainfall Intensity ◽  
Ground Cover ◽  
First Year ◽  
Mass Wasting ◽  
Soil Infiltration ◽  
Infiltration Capacity ◽  
The Past ◽  
Long Duration ◽  
Southwestern Usa

Abstract In the semiarid Southwestern USA, wildfires are commonly followed by runoff-generated debris flows because wildfires remove vegetation and ground cover, which reduces soil infiltration capacity and increases soil erodibility. At a study site in Southern California, we initially observed runoff-generated debris flows in the first year following fire. However, at the same site three years after the fire, the mass-wasting response to a long-duration rainstorm with high rainfall intensity peaks was shallow landsliding rather than runoff-generated debris flows. Moreover, the same storm caused landslides on unburned hillslopes as well as on slopes burned 5 years prior to the storm and areas burned by successive wildfires, 10 years and 3 years before the rainstorm. The landslide density was the highest on the hillslopes that had burned 3 years beforehand, and the hillslopes burned 5 years prior to the storm had low landslide densities, similar to unburned areas. We also found that reburning (i.e., two wildfires within the past 10 years) had little influence on landslide density. Our results indicate that landscape susceptibility to shallow landslides might return to that of unburned conditions after as little as 5 years of vegetation recovery. Moreover, most of the landslide activity was on steep, equatorial-facing slopes that receive higher solar radiation and had slower rates of vegetation regrowth, which further implicates vegetation as a controlling factor on post-fire landslide susceptibility. Finally, the total volume of sediment mobilized by the year 3 landslides was much smaller than the year 1 runoff-generated debris flows, and the landslides were orders of magnitude less mobile than the runoff-generated debris flows.

scholarly journals 2D Runout Modelling of Hillslope Debris Flows, Based on Well-Documented Events in Switzerland

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 70 ◽  
Author(s):  
Florian Zimmermann ◽  
Brian W. McArdell ◽  
Christian Rickli ◽  
Christian Scheidl
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Mass Movement ◽  
Clay Content ◽  
Systematic Evaluation ◽  
Mountain Areas ◽  
Flow Processes ◽  
Friction Parameters ◽  
Cohesive Interaction ◽  
Hillslope Debris Flow

In mountain areas, mass movements, such as hillslope debris flows, pose a serious threat to people and infrastructure, although size and runout distances are often smaller than those of debris avalanches or in-channel-based processes like debris floods or debris flows. Hillslope debris-flow events can be regarded as a unique process that generally can be observed at steep slopes. The delimitation of endangered areas and the implementation of protective measures are therefore an important instrument within the framework of a risk analysis, especially in the densely populated area of the alpine region. Here, two-dimensional runout prediction methods are helpful tools in estimating possible travel lengths and affected areas. However, not many studies focus on 2D runout estimations specifically for hillslope debris-flow processes. Based on data from 19 well-documented hillslope debris-flow events in Switzerland, we performed a systematic evaluation of runout simulations conducted with the software Rapid Mass Movement Simulation: Debris Flow (RAMMS DF)—a program originally developed for runout estimation of debris flows and snow avalanches. RAMMS offers the possibility to use a conventional Voellmy-type shear stress approach to describe the flow resistance as well as to consider cohesive interaction as it occurs in the core of dense flows with low shear rates, like we also expect for hillslope debris-flow processes. The results of our study show a correlation between the back-calculated dry Coulomb friction parameters and the percentage of clay content of the mobilised soils. Considering cohesive interaction, the performance of all simulations was improved in terms of reducing the overestimation of the observed deposition areas. However, the results also indicate that the parameter which accounts for cohesive interaction can neither be related to soil physical properties nor to different saturation conditions.

scholarly journals Talus fabric, clast morphology, and botanical Indicators of Slope Processes on the Chaos Crags (California Cascades), U.S.A.

2002 ◽  
Vol 52 (1) ◽  
pp. 47-68 ◽  
Author(s):  
Francisco L. Pérez
Keyword(s):  
Debris Flows ◽  
Snow Avalanches ◽  
Mass Wasting ◽  
Rectilinear Segment ◽  
The North ◽  
Normal Mass ◽  
Volcanic Debris ◽  
Dome Collapse ◽  
Geomorphic Processes ◽  
Chaos Crags

AbstractThe Chaos Crags, a group of dacite domes in the Cascades Mtns (California), were affected by volcanic debris avalanches ca. 1675 A.D.; these left a sizable deposit and a scar on the north mountain flank, now covered by talus. This report examines the fabric and morphology of talus debris, their spatial variation, and the geomorphic processes presently affecting the slope. The talus presents a bi-segmented profile with a steep upper rectilinear segment and a shorter concave, basal zone. Debris are sorted by size both along (larger clasts downslope) and across the talus (larger particles below the cliffs). Shape sorting is weaker, but clast sphericity increases, and elongation decreases, toward the footslope. Upper-talus fabrics (long axes parallel to talus plane and slope) show that clasts there move by sliding, while basal blocks are deposited by rockfall, which causes more iso- tropic fabrics. Field observations and botanical evidence indicate the overall significance of grain flows, which are prevalent duetoanabundantsupplyofrubbleonthe upper talus. Comparison with similar recent slopes and repeat photography suggest the Chaos talus formed swiftly following dome collapse, when much debris may have collected below the unstable rockwalls. The talus has experienced only modest sedimentation during the 20thcentury, and is currently affected by 'normal' mass-wasting processes, which also include snow avalanches and debris flows.

Cryoplanation Terraces: Indicators of a Permafrost Environment

1976 ◽  
Vol 6 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Richard D. Reger ◽  
Troy L. Péwé
Keyword(s):  
Mass Movement ◽  
Indirect Evidence ◽  
Summer Temperature ◽  
Climatic Data ◽  
Mass Wasting ◽  
Fine Grained ◽  
Permafrost Environment ◽  
Summer Temperatures ◽  
The Mean ◽  
July Temperature

Cryoplanation terraces are bedrock steps or terraces on ridge crests and hilltops. The tread or “flat” area is 10 to several hundred meters wide and long and slopes from 1 to 5° parallel to the ridge crests. Terrace scarps may be from 1 to 75 m high. Terraces are cut into all bedrock types and are best developed on closely jointed, fine-grained bedrock. The scarps and treads are covered with frost-rived rubble 1 to 2 m thick. The rubble on treads is perennially frozen at a depth of 1 to 2 m or less on sharp but inactive terraces in Alaska.Cryoplanation terraces exist in many parts of the world in present or past periglacial environments. They occur chiefly in nonglaciated regions and near the general altitude of snowline. Cryoplanation terraces form by scarp retreat as the result of nivation. Surficial debris is removed across the terrace tread by mass-wasting. Terrace morphology depends mainly upon climate, bedrock type, and terrace orientation.No climatic data are available from active terraces. Indirect evidence indicates that climatic requirements include low snowfall and cold summer temperatures. Shallow permafrost is necessary to provide moisture and a base for mass movement as well as a base for nivation.Hundreds of sharp but inactive terraces occur in some areas in Alaska where the summer temperature is colder than 10°C. When these terraces were active, temperatures were colder. Recent work in Alaska indicates that terraces were active in some areas when the mean July temperature was about 4°C. The mean annual air temperature probably was in the neighborhood of -12°C or colder.

scholarly journals A Detail on Landslide & its Types

2017 ◽  
pp. 19-27
Author(s):  
Rudolf Vukelic
Keyword(s):  
Debris Flows ◽  
Driving Force ◽  
Heavy Rainfall ◽  
Submarine Landslides ◽  
Mass Wasting ◽  
Rock Falls ◽  
Factors Affecting ◽  
Mountain Ranges ◽  
Wide Range ◽  
Coastal Cliffs

The term landslide or, less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rock falls, deep-seated slope failures, mudflows and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients: from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability which produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

scholarly journals Two multi-temporal datasets that track the enhanced landsliding after the 2008 Wenchuan earthquake

2019 ◽  
Vol 11 (1) ◽  
pp. 35-55 ◽  
Author(s):  
Xuanmei Fan ◽  
Gianvito Scaringi ◽  
Guillem Domènech ◽  
Fan Yang ◽  
Xiaojun Guo ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Temporal Evolution ◽  
The Tibetan Plateau ◽  
Mass Wasting ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
Rain Gauges ◽  
Multi Temporal ◽  
Coseismic Landslide

Abstract. We release two datasets that track the enhanced landsliding induced by the 2008 Mw 7.9 Wenchuan earthquake over a portion of the Longmen Mountains, at the eastern margin of the Tibetan Plateau (Sichuan, China). The first dataset is a geo-referenced multi-temporal polygon-based inventory of pre- and coseismic landslides, post-seismic remobilisations of coseismic landslide debris and post-seismic landslides (new failures). It covers 471 km2 in the earthquake's epicentral area, from 2005 to 2018. The second dataset records the debris flows that occurred from 2008 to 2017 in a larger area (∼17 000 km2), together with information on their triggering rainfall as recorded by a network of rain gauges. For some well-monitored events, we provide more detailed data on rainfall, discharge, flow depth and density. The datasets can be used to analyse, on various scales, the patterns of landsliding caused by the earthquake. They can be compared to inventories of landslides triggered by past or new earthquakes or by other triggers to reveal common or distinctive controlling factors. To our knowledge, no other inventories that track the temporal evolution of earthquake-induced mass wasting have been made freely available thus far. Our datasets can be accessed from https://doi.org/10.5281/zenodo.1405489. We also encourage other researchers to share their datasets to facilitate research on post-seismic geological hazards.

scholarly journals The Utilization of Black – White Panchromatic Aerial Photograph for Mass Movement Study in Karang Kobar Areas, Banjarnegara, Centra Java

2004 ◽  
Vol 11 (2) ◽  
Author(s):  
Imam Hardjono ◽  
Karmono Mangoensoekardjo ◽  
S Sutikno
Keyword(s):  
Remote Sensing ◽  
Physical Environment ◽  
Aerial Photograph ◽  
Mass Movement ◽  
Geological Structure ◽  
Aerial Photographs ◽  
Visual Interpretation ◽  
Mass Wasting ◽  
Quality Of Data ◽  
Central Java

This is the result of applied remote sensing  for geological study the mass wasting in Karangkobar, the district of Banjarnegara, Central Java. The study on the mass wasting use the remote sensing method, by interpreting the blackwhite panhromatic aerial photographs, on the scale 1 : 50,000. The study is aimed at 1) revealing the capacity of the aerial photograph in supporting the study the mass wasting that an be identified by the aerial photographs; 2) to find out the influence of the physical environment and land-use on the mass wasting processes. The study in performed by using the visual interpretation method of the scale 1 : 50,000 black-white panchromati aerial photograph taken in 1994, using mirror stereoscope. The outcome of the aerial photograph interpretation is varis the quality of data and information. The data of interpretation of aerial photograph and the varis outcome in the spot are further tested in terms of its accuracy, particularly in its reltion with the aerial photograph interpretation. The technique of data analysis of the physical environment and the mass wasting is descriptive – comparative. The result of the study shows that the 1 : 50,000 black-white panchromatic aerial photograph can be used to identify and study both the mass wasting and influence of the physical environment on the mass wasting processes. The degree of identifying the mass wasting based on the aerial photograph interpretation is 75%. Compared to the previous studies, the present study hows that the mass wasting can be identified more easily by means of the 1 : 50,000 black – white panchromatic aerial photograph. Identifying the distribution of mass wasting are: a) the geological element (rock, geological structure, and stratigraphy); b) geomorphological elements (landform and the forming processes); the water condition (surface water and groundwater); and landuse (type and distribution). White marl – claystone type is the physical environmentsal element that has the most type is the physical environmentsal element that has the most dominant influence on the occuring of mass wasting in Karangkobar area.

Influence of Wildfire on Earth Surface Processes and Geomorphology

2021 ◽  
Author(s):  
Paul Santi ◽  
Francis Rengers
Keyword(s):  
Debris Flows ◽  
Management Practices ◽  
Mass Movement ◽  
Soil Formation ◽  
Alluvial Fan ◽  
Water Repellent ◽  
Alluvial Fans ◽  
Stream Channels ◽  
Sediment Delivery ◽  
Recurrence Intervals

<p>Wildfire is a global phenomenon that is expected to increase in extent and severity due to shifting land management practices and climate change. It removes vegetation, deposits ash, influences water-repellent soil formation, and physically weathers rock. These changes typically lead to increased erosion through sheetwash, rilling, rock spalling, and dry ravel, as well as increased mass movement in the form of floods, debris flows, rockfall, and landslides. Post-wildfire changes in these processes bring about landform changes as hillslopes are lowered and stream channels aggrade or incise at increased rates. Research has documented increases in erosion after wildfire ranging from 2-1000 times the pre-fire rates. Post-wildfire landscape lowering by erosion has been measured in the western U.S. at magnitudes of 2 mm per year, with sediment delivery at the mouths of canyons increased in the range of 160-1000% during the post-wildfire window of disturbance. Furthermore, post-wildfire sediment transport enhances the development of alluvial fans, debris fans, and talus cones. Debris-flow likelihood is increased following wildfire, such that modest rainstorms with <2 year recurrence intervals are typically sufficient to trigger debris flows with volumes much larger (270-540%) than at unburned sites. In the western U.S., as much as 25-50% of alluvial fan accumulation can be attributed to post-wildfire debris flows and other post-wildfire fluvial transport. The window of disturbance to the landscape caused by wildfire is typically on the order of three to four years, with some effects persisting up to 30 years.  Consequently, wildfire is an important agent of geomorphic change.</p>

Chapter 28: Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea

2020 ◽  
pp. 579-597
Author(s):  
David R. Cooke ◽  
Stephanie Sykora ◽  
Erin Lawlis ◽  
Jacqueline L. Blackwell ◽  
Mathieu Ageneau ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Papua New Guinea ◽  
Late Stage ◽  
New Guinea ◽  
Hydrothermal Activity ◽  
Epithermal Gold ◽  
Mass Wasting ◽  
Heated Zone ◽  
Epithermal Mineralization ◽  
Epithermal Gold Deposit

Abstract The Lihir gold deposit, Papua New Guinea, is the world’s largest alkalic low-sulfidation epithermal gold deposit in terms of contained gold (50 Moz). The deposit formed over the past million years and records a progression from porphyry- to epithermal-style hydrothermal activity. The early porphyry stage was characterized by biotite-anhydrite-pyrite ± K-feldspar ± magnetite alteration and weak gold ± copper mineralization and produced abundant anhydrite ± carbonate veins and anhydrite ± biotite-cemented breccias. These features collectively characterize the deep-seated anhydrite zone at Lihir. Several hundred thousand years ago, one or more catastrophic mass-wasting events unroofed the porphyry system after porphyry-stage hydrothermal activity ceased. Mass wasting may have been facilitated in part by dissolution of porphyry-stage anhydrite veins. Epithermal mineralization occurred after sector collapse, resulting in phreatic and hydraulic brecciation and veining, widespread adularia-pyrite ± carbonate alteration, and formation of mineralized zones at Lienetz, Minifie, Kapit, Kapit NE, Coastal, and Borefields. A NE- to ENE-striking fault array localized several of these orebodies. The pyrite-rich veins and pyrite-cemented breccias that formed during epithermal-stage hydrothermal activity define the sulfide zone at Lihir. This zone mostly contains refractory gold in pyrite, with minor free gold and precious metal tellurides hosted in late-stage quartz veins. A period of diatreme volcanism disrupted the Luise amphitheater during the latter stages of epithermal mineralization. The diatreme breccia complex truncated several of the epithermal ore zones and was crosscut locally by late-stage epithermal veins. Recent geothermal activity produced a steam-heated clay alteration blanket that has overprinted the refractory sulfide-rich epithermal assemblage near the present-day land surface. Gold was remobilized downward from the steam-heated zone into the sulfide zone during argillic and advanced argillic alteration, producing thin gold-rich rims around pyrite grains. This process produced a high-grade tabular enrichment zone immediately beneath the base of the clay blanket.

Sign in / Sign up

Export Citation Format

Share Document