Why are landslides more common on steep slopes?

Why are landslides more common on steep slopes?

A landslide occurs because the force of gravity becomes greater than either friction or the internal strength of the rock, soil, or sediment. Pushing the rock is easier if the surface slopes downhill or is slippery. The same is true for landslides—steeper slopes have less friction, making landslides more common.

How does road construction associated with timber harvesting contribute to landslide hazards answer choices?

The geology in the adjacent hillslopes was dominated by weak rocks. How does road construction associated with timber harvesting contribute to landslide hazards? The roads alter the movement of surface water and groundwater. The fluid pressure provides partial support for the overlaying rock mass.

Which of the following will make a landslide more likely to occur?

Landslides are more likely to occur in mountainous areas with abundant precipitation and exposed soil.

What strategy stabilized the Portuguese Bend landslide?

What strategy helped to stabilize the Portuguese Bend landslide? The geology in the adjacent hillsides was dominated by weak rocks. It reduces saturation of soils and rocks, thereby increasing resisting forces.

Why is it called Portuguese Bend?

The name Portuguese Bend comes from the whaling activities of Portuguese whalemen from the Azores. An Azorean shore whaling captain named José Machado brought shore whaling to this bend in the coastline north of San Pedro Bay after the closure of the San Pedro Bay whaling station on Deadman’s Island in or about 1862.

What caused La Conchita landslide?

The landslide occurred after a 15-day period of unprecedented records of rainfall in Southern California. It is likely that the new rainfall did not enter the deposits left behind after the 1995 landslide, but slid off it taking surface debris and few new materials with it.

Are the increasing fires in California impacting the frequency of landslides?

The results show Californians are now facing a double whammy of increased wildfire and landslide risk caused by climate change-induced shifts in the state’s wet and dry seasons, according to researchers who mapped landslide vulnerability in the southern half of the state.

Is it safe to live in La Conchita?

After the 2005 tragedy, research geologist Randy Jibson of the U.S. Geological Survey authored a study of La Conchita. He said the remaining houses are in one of the most slide-prone areas in the nation and not safe places to live.

When was the last landslide in La Conchita?

Jan

What was were the cause s of the La Conchita mudslides of 1995 and 2005?

The 1995 landslide apparently occurred as a result of an extraordinarily wet year. Mean seasonal rainfall at Ojai (20 km [12 mi] northeast of La Conchita) from October 1 through March 3 (the day before the landslide occurred) is 390 mm (15.37 in) (National Oceanic and Atmospheric Administration, 1994a, 1995a).

What kind of landslide was La Conchita?

In La Conchita, there was a landslide and earthflow in the spring of 1995 (see figure 1). People were evacuated and the houses nearest the slide were completely destroyed. This is a typical type of landslide.

What is the difference between a debris flow and an earth flow?

A rockslide is the sliding of rock material down a mountain. A debris flow is the movement of a water-laden mass of loose mud, sand, soil, rock and debris down a slope. A debris flow can dash down the slope, reaching speeds of 100 miles per hour or greater.

How fast can a debris flow travel?

Debris flows can travel at speeds up to and exceeding 35 mph and can carry large items such as boulders, trees, and cars. If a debris flows enters a steep stream channel, they can travel for several miles, impacting areas unaware of the hazard.

What are three types of mass wasting incidents?

The most common mass-wasting types are falls, rotational and translational slides, flows, and creep. Falls are abrupt rock movements that detach from steep slopes or cliffs.

How is a lahar different from a debris flow?

At Mount Rainier, scientists use the word lahar for large flows of eruption or landslide origin with potential to travel to densely populated valleys, and use the term debris flow for much smaller, more common events caused by glacier floods and precipitation, which stay generally within park boundaries.

Why is lahar dangerous?

Lahars and excess sediment cause serious economic and environmental damage to river valleys and flood plains. Over a period of weeks to years after a volcanic eruption, the erosion and transportation of loose volcanic deposits can lead to severe flooding in areas far downstream from a volcano.

What is the best option to prevent your house from being covered by a debris flow?

You can’t stop or change the path of a debris flow. However, you may be able to protect your property from floodwaters or mud by use of sandbags, retaining walls or k-rails (Jersey barriers). In mud and debris flow areas, consider building channels or deflection walls to try to direct the flow around buildings.

What damage can a lahar cause?

People caught in the path of a lahar have a high risk of death from severe crush injuries, drowning or asphyxiation. Lahars are often highly erosive to river banks and eyewitnesses should remain at a safe distance. Lahar events will cause destruction of buildings, installations and vegetation caught in their path.

What can be done to reduce the impact of lahar?

Strategies include (1) hazard avoidance with land-use planning and zonation; (2) hazard modification with engineered protection structures (bypass channel and deflection berm); (3) hazard warning to allow for timely evacuation; and (4) hazard response and recovery, which minimize long-term impacts after a lahar has …

What places must be avoided to be free from lahar flow?

During the occurrence of a lahar, traveling in river valley bottoms, low relief areas and roads that cross the valleys must be avoided.

How do you protect yourself from a lahar?

Protecting yourself during ashfall

1. Stay inside, if possible, with windows and doors closed.
2. Wear long-sleeved shirts and long pants.
3. Use goggles to protect your eyes.
4. Exposure to ash can harm your health, particularly the respiratory (breathing) tract.
5. Keep your car or truck engine switched off.

How far can a lahar travel?

On steep slopes, lahar speeds can exceed 200 kilometres per hour (120 mph). With the potential to flow distances of more than 300 kilometres (190 mi), a lahar can cause catastrophic destruction in its path.

Are lahars dangerous for human beings?

Many times, that allows for enough forewarning to escape if you are downriver, but the 1985 eruption of Nevado del Ruiz in Colombia proved that a lack of preparation can lead to over 20,000 deaths. Due to their density, lahars can destroy infrastructure and homes and bury towns (and people) rapidly.

What is the most dangerous type of hazard?

Biological hazards

What is the best reason why most lava flows aren’t a threat to human life?

What is the best reason why most lava flows aren’t a threat to human life? Lava flows usually don’t flow very quickly, so people can outrun them.

How dangerous is Mt Vesuvius?

Mount Vesuvius is considered to be one of the most dangerous volcanoes in the world because of its proximity to the city of Naples and the surrounding towns on the nearby slopes. The volcano is classed as a complex stratovolcano because its eruptions typically involve explosive eruptions as well as pyroclastic flows.