100 miles per hour
“It has been known for more than a century that very large,dry landslides travel in a fluid-like manner,attaining speeds of more than100 miles per hour,traveling tens to hundreds of kilometers from their sources and even climbing uphill as they overwhelm surprisingly large areas,” says Melosh,who was a part of the research team.
What is a landslide and what causes one?
What is a Landslide? A landslide is the movement of rock, earth, or debris down a sloped section of land. Landslides are caused by rain, earthquakes, volcanoes, or other factors that make the slope unstable. Experts also term landslides as one type of ‘mass wasting’.
Is a landslide a natural disaster?
While landslides are considered naturally occurring disasters, human-induced changes in the environment have recently caused their upsurge. Although the causes of landslides are wide ranging, they have 2 aspects in common; they are driven by forces of gravity and result from failure of soil and rock materials that constitute the hill slope:
Where do landslides occur most?
Where do landslides occur the most? The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. Alaska and Hawaii also experience all types of landslides.
What are landslides and how do they occur?
Landslides occur when masses of rock, earth, or debris move down a slope. Debris flows, also known as mudslides, are a common type of fast-moving landslide that tends to flow in channels. Landslides are caused by disturbances in the natural stability of a slope. They can accompany heavy rains or follow droughts, earthquakes, or volcanic eruptions.
What is a Landslide?
The term landslide includes a wide range of ground movements, such as rock falls, deep failure of slopes, and shallow debris flows. Although gravity acting on an over-steepened slope is the primary reason for a landslide, there are other contributing factors:
Where do Landslides Occur?
Landslides occur in every state and U.S. territory. The Appalachian Mountains, the Rocky Mountains and the Pacific Coastal Ranges and some parts of Alaska and Hawaii have severe landslide problems. Any area composed of very weak or fractured materials resting on a steep slope can and will likely experience landslides.
Why Study Landslides?
Landslides are a serious geologic hazard common to almost every State in the United States. It is estimated that in the United States, they cause in excess of $1 billion in damages and from about 25 to 50 deaths each year. Globally, landslides cause many billions in damages and thousands of deaths each year.
What are some examples of landslides?
In either instance, and particularly in an urban setting, their effects can be catastrophic, both personally and economically. For example, the Cincinnati area is one of the most active regions in the country for landslides.
What is translational landslide?
A "translational" landslide can happen rapidly and result in all of the soil on a hillside being stripped off and filling the area at the bottom of the slope. Prevention of a translational landslide, or its subsequent cleanup, can be significant. A third type of landslide is "rotational.".
What is the third type of landslide?
A third type of landslide is "rotational.". It, too, can be slow, but it is a deep movement of the soil, and its effects can be devastating; for example, the 1973 Mt. Adams slide in Cincinnati cost tens of millions of dollars to stabilize after it had destroyed two streets and sixteen houses.
Why does soil move downhill?
Soils perched on slopes naturally move downhill as part of the process of erosion. Soil that moves downhill slowly is said to "creep", and its movement is often slow and shallow enough to be anticipated and managed with a modest effort.
Is gravity a constant force?
With a better understanding of the underlying geology and the geologic processes at play, however, successful property development on hills can be accomplished. Gravity is a constant force on all earth materials.
What Besides Erosion Can Cause Landslides?
Even though erosion is a big reason that there are landslides, other things such as when big snows melt and when there are heavy rainstorms, the material on the slope can still be loosened and can cause landslides to happen.
What Areas Are More at Risk from Landslide?
People that live in areas that are hilly or mountainous have a chance to experience a landslide.
What Did You Learn?
What is a landslide? A landslide is when rock and debris fall from a steep slope.
Why do landslides happen?
The reason that landslides happen is that gravity pulls the land downward, but it is triggered by environmental conditions such as earthquakes, rainfall, erosion, slope cut, and construction.
What causes land landslides?
Landslides happen when there is wastes or movement of the ground that causes things to happen such as rockfalls, slope failures, or mudflows. Landslides can happen anywhere, and they can happen on a small slope or a steep slope and can occur on the coastal cliffs, underwater, or in the mountain ranges.
Why do land slides cause tsunamis?
Landslides can cause Tsunamis because when an island or a volcano collapses into the water, it can cause water to be pushed and can cause Tsunamis to happen .
How long will a landslide last?
Scientists cannot predict how long a landslide will last.
How do wildfires affect the US?
Wild land fires are inevitable in the western United States. Expansion of human development into forested areas has created a situation where wildfires can adversely affect lives and property, as can the flooding and landslides that occur in the aftermath of the fires. There is a need to develop tools and methods to identify and quantify the potential hazards posed by landslides produced from burned watersheds. Post-fire landslide hazards include fast-moving, highly destructive debris flows that can occur in the years immediately after wildfires in response to high intensity rainfall events, and those flows that are generated over longer time periods accompanied by root decay and loss of soil strength. Post-fire debris flows are particularly hazardous because they can occur with little warning, can exert great impulsive loads on objects in their paths, and can strip vegetation, block drainage ways, damage structures, and endanger human life. Wildfires could potentially result in the destabilization of pre-existing deep-seated landslides over long time periods.
How much did it cost to fix the landslide in Utah?
The Thistle, Utah, landslide cost in excess of $200 million dollars to fix. The landslide occurred during the spring of 1983, when unseasonably warm weather caused rapid snowmelt to saturate the slope. The landslide destroyed the railroad tracks of the Denver and Rio Grande Western Railway Company, and the adjacent Highway 89. It also flowed across the Spanish Fork River, forming a dam. The impounded river water inundated the small town of Thistle. The inhabitants of the town of Thistle, directly upstream from the landslide, were evacuated as the lake began to flood the town, and within a day the town was completely covered with water. Populations downstream from the dam were at risk because of the possible overtopping of the landslide by the lake. This could cause a catastrophic outburst of the dam with a massive flood downstream. Eventually, a drain system was engineered to drain the lake and avert the potential disaster.
What is NLIC in landslide?
The NLIC is designed to serve landslide researchers, geotechnical practitioners engaged in landslide stabilization, and anyone else concerned in any way with landslide education, hazard, safety, and mitigation. Every state in the US has a geoscience agency and most have some landslide information.
What causes debris flows in a wildfire?
These flows are initiated by heavy periods of rainfall, but sometimes can happen as a result of short bursts of concentrated rainfall or other factors in susceptible areas. Burned areas charred by wildfires are particularly susceptible to debris flows, given certain soil characteristics and slope conditions.
Why do earthquakes occur in steep landslide areas?
The occurrence of earthquakes in steep landslide-prone areas greatly increases the likelihood that landslides will occur, due to ground shaking alone or shaking- caused dilation of soil materials, which allows rapid infiltration of water.
How fast can a land slide move?
Debris flows can travel down a hillside at speeds up to 200 miles per hour (more commonly, 30 – 50 miles per hour), depending on the slope angle, water content, volume of debris, and type of earth and debris in the flow.
What is the movement of a mass of rock, debris, or earth down a slope due to gravity?
A landslide is defined as the movement of a mass of rock, debris, or earth down a slope due to gravity. The materials may move by falling, toppling, sliding, spreading, or flowing. What causes a landslide? Almost every landslide has multiple causes.
What is a landslide that moves on a slope?
Landslides occur when masses of rock, earth, or debris move down a slope. Debris flows, also known as mudslides, are a common type of fast-moving landslide that tends to flow in channels.  Mudslides develop when water rapidly accumulates in the ground and results in a surge of water-saturated rock, earth, and debris.
What can land landslides cause?
Landslides and mudflows can cause tons of damage, some of which can lead to actual injury including: Rapidly moving water and debris can lead to trauma; Broken electrical, water, gas, and sewage lines that can result in injury or illness. 
How fast does a landslide travel?
On steep hillsides, debris flows begin as shallow landslides that liquefy and accelerate. A typical landslide travels at 10 miler per hour, but can exceed 35 miles per hour. 
What was the largest landslide in history?
The May 1980 eruption of Mount St. Helens caused the largest landslide in history. A rockslide debris avalanche large enough to fill 250 million dump trucks to the brim traveled about 14 miles, destroying, amoung many things, nine highway bridges. 
How many people died in the Rio de Janeiro landslide?
There have been many landslides throughout the years including the Rio de Janeiro landslide in 2011 which caused over 600 deaths. 
Where do mudslides start?
Mudslides usually start on steep slopes and can be activated by natural disasters.  Areas where wildfires or human modification of the land have destroyed vegetation on slopes are particularly vulnerable to landslides during and after heavy rains.