What is the difference between a debris flow and creep

In addition to the tools and strategies cited below that are profiled in this guide, hillside development standards are also important tools for reducing potential risks from landslides and similar hazards. Hillside standards often include limitations on grading and earth removal and standards for site improvements such as retaining walls. Addressing Hazards in Plans and Policies. Strengthening Incentives. Protecting Sensitive Areas. Improving Site Development Standards.

Improving Buildings and Infrastructure. Enhancing Administration and Procedures. Skip to main content. You are here Home » Hazards. Related Hazards. Assessing the Risk of Geologic and Soil Hazards. Available Data Sources. CGS also manages a GIS library of digital geologic data that can be combined with local datasets to better understand the relationship between community assets and areas of potential hazard concern. Applicable Planning Tools and Strategies. Get Involved About Submit a case study!

As shown in Figure However, it is not actually known what triggered this event as the weather was dry and warm during the preceding weeks, and there was no significant earthquake in the region. The Hope Slide Figure The slide at Mt. Meager west of Lillooet was also a rock avalanche, and rivals the Hope Slide as the largest slope failure in Canada during historical times Figure Creep , which normally only affects the upper several centimetres of loose material, is typically a type of very slow flow, but in some cases, sliding may take place.

Creep can be facilitated by freezing and thawing because, as shown in Figure The same effect can be produced by frequent wetting and drying of the soil.

In cold environments, solifluction is a more intense form of freeze-thaw-triggered creep. Creep is most noticeable on moderate-to-steep slopes where trees, fence posts, or grave markers are consistently leaning in a downhill direction Figure Slump is a type of slide movement as a mass that takes place within thick unconsolidated deposits typically thicker than 10 m.

Slumps involve movement along one or more curved failure surfaces, with downward motion near the top and outward motion toward the bottom Figure They are typically caused by an excess of water within these materials on a steep slope.

Debris flows and debris floods may travel long distances down canyons before spreading out across a valley floor where, often unfortunately, the land may be occupied by people and property, sometime causing significant death and destruction.

A lahar is a landslide mudflow or debris flow consisting of volcanic pyroclastic material, water, and possibly ice and other debris that discharges down the flank of a volcano. Lahars occur as a result of volcanic eruptions, earthquakes, or the gravitational collapse of volcano or summit glaciers. The word lahar applies both to the process or deposits formed after the landslide event.

Creep is the slow, more or less continuous downslope movement of surface materials rock and soil under gravitational stresses. Creep occurs on many hillslope areas, but is particularly common in areas that experience seasonal freezing and thawing of the land's surface. Trees on a slow, creeping hillside tend to gradually realign themselves upward as the root stocks slowly rotate downhill over time.

Although a perceptively slow landsliding process, creep is often responsible for the rupture of underground pipelines, the cracking of foundations, roads, and other infrastructure built on hillsides, particularly in regions with temperate climates having warm summers and cold winters with highly fluctuating daily and seasonal temperature ranges.

Chapparral land is especially susceptible to debris flows after a fire. The rapidly moving water cascades down the slopes, and into the canyons and valleys below.

It picks up speed and some debris as it descends the valley walls. In the valley itself, months of dry ravel, loose soil and rocks that have rolled or slid off the slope, begins to move with the water.

As the system gradually picks up speed, the flow takes on the characteristics of a basic river system. The faster the water flow, the more the water can pick up. As the water picks up more mud and rocks, it begins to resemble a fast flowing river of concrete. This wall of debris can move so rapidly that it can pluck boulders the size of cars from the floors of the canyons and hurl them along the path of the flow. It's the speed and enormity of carried particles that makes a debris flow so dangerous.

Boulders crash through homes and the mud-water mix fills in the rooms sometime totally overtaking the house. People have tried many methods for stopping or diverting debris flows. In California, catch basins have ben constructed to "catch" the debris.

Some basins have special overflow ducts with screens to remove the water from the flow and allow more room for the bigger items that may be washed in and take up needed space. Catch basin in British Columbia, Canada Debris Chute in British Columbia, Canada Debris flows happen so rapidly that there is really no way to monitor one until it is on top of you.

Instruments in catch basins and flow channels can measure the rate or discharge of the flow by calculating the amount volume of material per unit of time usually seconds. Mud flows and Lahars Extremely heavy rain, or a sudden thaw can trigger these types of flows.

In the case of lahars, a sudden thaw of mountain snow due to a volcanic eruption can send a torrent of mud, ash, and hot water down the slope of the volcano and over neighboring towns. As can be seen from this photograph of the unfortunate town of Armero, a lahar can overtake a town far from a volcano.