What is an example of mass wasting?
Mass wasting is the movement of rock and soil down slope under the influence of gravity. Rock falls, slumps, and debris flows are all examples of mass wasting. Often lubricated by rainfall or agitated by seismic activity, these events may occur very rapidly and move as a flow.
What is the most common trigger for mass wasting events?
Excessive precipitation is the most common trigger. Mass-wasting events are classified by their type of movement and material, and they share common morphological surface features. The most common types of mass-wasting events are rockfalls, slides, flows, and creep. Mass-wasting movement ranges from slow to dangerously rapid.
What is the movement of rocks during mass wasting?
Loose material along with overlying soils are what typically move during a mass-wasting event. Moving blocks of bedrock are called rock topples, rock slides, or rock falls, depending on the dominant motion of the blocks. Movements of dominantly liquid material are called flows. Movement by mass wasting can be slow or rapid.
What drives mass wasting?
This chapter discusses the fundamental processes driving mass-wasting, types of mass wasting, examples and lessons learned from famous mass-wasting events, how mass wasting can be predicted, and how people can be protected from this potential hazard. Mass wasting is the downhill movement of rock and soil material due to gravity.
What is the fastest form of mass wasting?
A rock fall are the fastest of all landslide types and occurs when a rock falls through the air until it comes to rest on the ground—not too complicated.
What is rapid movement in mass wasting?
A landslide, also called a landslip, is a relatively rapid movement of a large mass of earth and rocks down a hill or a mountainside. Landslides can be further classified by the importance of water in the mass wasting process.
What type of mass wasting does the most damage?
Creep is the most economically damaging and widespread type of material flow. Slow mass movement transports a greater volume of material than does rapid mass movement. Slumps occur most commonly in well-consolidated material.
What is an example of rapid mass movement?
Rapid mass movement includes large amount of debris, soil, boulders and rock pieces etc, e.g. landslides and sheet erosion or displacement of the upper rock strata in large amount to uncover the rocks lying below.
What is the slowest form of mass wasting?
The slowest and least noticeable, but most widespread of the slow mass wasting categories is creep. Creep involves the entire hillside, and is characterized by very slow movement of soil or rock material over a period of several years.
Which type of mass wasting occurs most slowly?
Which type of mass wasting occurs most slowly? Creep.
Which of the following form of mass wasting is relatively fast and wet compared to the others?
wedging. Which of the following form of mass wasting is relatively fast and wet compared to the others? Mudflow. An earthflow is most conspicuous in ________ where a bulging lobe of material pushes out onto a valley floor.
Which of the following mass wasting happens quickly and in very wet conditions?
Soil Creep Flows are rapidly moving mass-wasting events in which the loose material is typically mixed with abundant water, creating long runouts at the slope base.
What are the 4 types of mass wasting?
There are four main types of mass wasting which are slumps, rockslides, debris flow, and earthflow. Slumps are a downslope movement of semi-consolidated material along curved or planar surfaces.
Where do the most rapid mass wasting events occur quizlet?
In what kind of setting do most rapid mass-wasting events occur? Areas of rugged, geologically young mountains (ex. landslides).
What is the most common mass wasting trigger?
Increased water content within the slopeIncreased water content within the slope is the most common mass-wasting trigger. Water content can increase due to rapidly melting snow or ice or an intense rain event.
What are 3 types of mass movement?
There are four different types of mass movement:Rockfall. Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.Mudflow. Saturated soil (soil filled with water) flows down a slope.Landslide. Large blocks of rock slide downhill.Rotational slip. Saturated soil slumps down a curved surface.
What is mass wasting?
Mass wasting is a type of erosion, and it is capable of making big changes to the side of a mountain. These changes can happen suddenly, as in one minute the rock is there and the next it is gone, or it can happen more slowly over time.
What happens when a wave comes ashore and washes away a sandcastle?
This is similar to what happens when a wave comes ashore and washes away a sandcastle. The abundant water breaks apart the small sand particles and destroys the structural stability of the castle you spent the afternoon building. If an area has decreased vegetation, it will be more prone to mass wasting.
What is the term for the sliding of rock material down a mountain?
Without the base, the outer sections of the mountain slumps down as a unit or multiple units. A rockslide is another example of mass wasting of a slope. A rockslide is the sliding of rock material down a mountain. It is similar to a slump, but a rockslide does not move along a curved surface like a slump.
What forces pull rocks and debris down the slope of a mountain?
Gravity is constantly trying to pull rock and debris down the slope of a mountain. At the same time, the resistive forces of the mountain, including the cohesive strength and internal friction between the materials, referred to as the mountain's shear strength, constantly pulls back against gravity.
What is debris flow?
A debris flow is the movement of a water-laden mass of loose mud, sand, soil, rock and debris down a slope. Some debris flows move slowly while others can pick up momentum on steep slopes and reach speeds of 100 miles per hour or greater, sweeping away anything in their path, including trees, bridges, houses or roads.
Does steepness increase mass wasting?
For instance, an increased slope steepness increases mass wasting simply because the gravitational force acting on a steep slope is greater than the force acting on a gentle slope. Increasing the steepness of a slope is one way man can increase mass wasting.
Do rocks slide down a curved surface?
It is similar to a slump, but a rockslide does not move along a curved surface like a slump. Therefore, in a rockslide, we see rocks sliding down a pre-existing surface, such as an underlying layer of rock. In a way, it is as if the rocks are moving down a slide on a playground.
What are the types of mass wasting?
Types of Mass Wasting. Rockfalls and rockslides. Rockfalls occur when pieces of rock break loose from a steep rock face or cliff. These result from the rock face being undercut by rivers or wave action. Frost wedging may also eventually loosen large blocks, causing them to fall. The accumulation of rock debris at the base ...
What is a mudflow on a volcanic slope called?
A mudflow originating on a volcanic slope is called a lahar. The deadliest variety of debris flow is the debris avalanche, a rapidly churning mass of rock debris, soil, water, and air that races down very steep slopes.
What is mudflow in biology?
The soil finally settles on level ground at the base. A mudflow is a liquidy mass of soil, rock debris, and water that moves quickly down a well‐defined channel.
What is debris flow?
Debris flows are defined as mass‐wasting events in which turbulence occurs throughout the mass. Varieties of these are called earthflows, mudflows, and debris avalanches. When earth material moves down a hillside as a fluidlike mass, it is called an earthflow.
What is the term for the movement of Earth's surface as a unit along a curved surface?
Slump . Earth material that has moved as a unit along a curved surface is called slump. A slumped mass of sediment is typically clay rich. Slump usually results when the geometrical stability of a slope is compromised by the undercutting of its base, such as by wave action, a meandering river, or construction.
What causes mudflows in a mountainous environment?
Mudflows occur most often in mountainous semiarid environments with sparse vegetation and are triggered by heavy rainfall that saturates the loose soil and sediment. They are also the natural result of volcanic ash build‐ups on flanks of volcanoes and of forest fires that have exposed the soil to rapid erosion.
Why is separation of rock more likely along these planes?
Separation of the rock is more likely along these planes because of their reduced shear strength. Water also tends to be channeled along these planes, which increases slippage. Collisions down the slope generally break the rock mass into rubble that eventually comes to rest. If steep slopes are involved, a fast‐moving rock avalanche may result.
What is mass wasting?
Mass wasting is the downhill movement of rock and soil material due to gravity. The term landslide is often used as a synonym for mass wasting, but mass wasting is a much broader term referring to all movement downslope. Geologically, landslide is a general term for mass wasting that involves fast-moving geologic material.
How do you know if a landslide is a mass wasting?
Landslides have several identifying features that can be common across the different types of mass wasting. Note that there are many exceptions, and a landslide does not have to have these features. Displacement of material by landslides causes the absence of material uphill and the deposition of new material downhill, and careful observation can identify the evidence of that displacement. Other signs of landslides include tilted or offset structures or natural features that would normally be vertical or in place.#N#Many landslides have escarpments or scarps. Landslide scarps, like fault scarps, are steep terrain created when movement of the adjacent land exposes a part of the subsurface. The most prominent scarp is the main scarp, which marks the uphill extent of the landslide. As the disturbed material moves out of place, a step slope forms and develops a new hillside escarpment for the undisturbed material. Main scarps are formed by movement of the displaced material away from the undisturbed ground and are the visible part of slide rupture surface.
What causes a landslide to occur?
It could be rapid snowmelt, intense rainfall, earthquake shaking, volcanic eruption, storm waves, rapid- stream erosion, or human activities, such as grading a new road. Increased water content within the slope is the most common mass-wasting trigger. Water content can increase due to rapidly melting snow or ice or an intense rain event. Intense rain events can occur more often during El Niño years. Then, the west coast of North America receives more precipitation than normal, and landslides become more common. Changes in surface-water conditions resulting from earthquakes, previous slope failures that dam up streams, or human structures that interfere with runoff, such as buildings, roads, or parking lots can provide additional water to a slope. In the case of the 1959 Hebgen Lake rock slide, Madison Canyon, Montana, the shear strength of the slope may have been weakened by earthquake shaking. Most landslide mitigation diverts and drains water away from slide areas. Tarps and plastic sheeting are often used to drain water off of slide bodies and prevent infiltration into the slide. Drains are used to dewater landslides and shallow wells are used to monitor the water content of some active landslides.
What is a landslide?
Geologically, landslide is a general term for mass wasting that involves fast-moving geologic material. Loose material along with overlying soils are what typically move during a mass-wasting event. Moving blocks of bedrock are called rock topples, rock slides, or rock falls, depending on the dominant motion of the blocks.
How fast was the 2014 Oso landslide?
2014, Oso Landslide, Washington: On March 22, 2014, a landslide of approximately 18 million tons (10 million yd 3) traveled at 64 kph (40 mph), extended for nearly a 1.6 km (1 m), and dammed the North Fork of the Stillaguamish River.
What is used to drain water from a slide?
Tarps and plastic sheeting are often used to drain water off of slide bodies and prevent infiltration into the slide. Drains are used to dewater landslides and shallow wells are used to monitor the water content of some active landslides. An oversteepened slope may also trigger landslides.
What happens if you add water to a sandcastle?
But if too much water is added to the pore spaces of the sandcastle, the water decreases the shear strength, lowers the angle of repose, and the sandcastle collapses.