Why do debris flows happen

Home Earth Environment. Credit: azgs. Debris flow channel in Ladakh, near the northwestern Indian Himalaya, produced in the storms of August Deforestation like this clearcut in Sumatra, Indonesia can result in debris flows. Credit: worldwildlife. Credit: NASA. Source: Universe Today. Citation : What is a debris flow? This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission.

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Send Feedback. Thank you for taking time to provide your feedback to the editors. E-mail the story What is a debris flow? Your friend's email. Your email. Considerable literature and research are available concerning landslides, but unfortunately little of it is synthesized and integrated to address the This set of videos presents about 18 hours of footage documenting the experiments conducted at the USGS debris-flow flume from to Owing to improvements in video technology over the years, the quality of footage from recent experiments generally exceeds that from earlier experiments.

Use the list below to access the individual videos Landslides occur and can cause damage in all 50 States. Severe storms, earthquakes, volcanic activity, coastal wave attack, and wildfires can cause widespread slope instability. Landslide danger may be high even as emergency personnel are providing rescue and recovery services. To address landslide hazards, several questions must be considered A new landslide guidebook released February 5 is now available for Puerto Rico residents to learn more about the landslide hazards that can impact the island.

The U. Geological Survey today unveiled a new web-based interactive map that marks an important step toward mapping areas that could be at higher risk for future landslides. In collaboration with state geological surveys and other federal agencies, USGS has compiled much of the existing landslide data into a searchable, web-based interactive map called the U.

Landslide Inventory Map. When wildfires spread and scorch the earth, people like Penny Luehring have to act fast. Secondary impacts such as debris flows can be devastating to nearby communities. The Dec. After the fire, the USGS installed an automated rain-triggered camera to monitor post-wildfire flooding and debris flow in a small canyon above the Las Lomas debris basin in Duarte.

This video shows the peak flow triggered by an intense rainstorm on January 20, After the fire, the USGS installed an automated rain-triggered camera to monitor post-wildfire flooding and debris flow at the outlet of a small 0.

This video shows the initial surge and peak flow triggered by an intense rainstorm on July 19, Debris flows are hazardous flows of rock, sediment and water that surge down mountain slopes and into adjacent valleys. Spectacular debris flow footage, recorded by Franck Lavigne of the. Debris flow was generated during a burst of high-intensity rainfall over the area burned by the September Station Fire. Skip to main content.

Search Search. Natural Hazards. Apply Filter. What should I know about wildfires and debris flows? Wildland 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 Can major landslides and debris flows happen in all areas of the U.

Landslides can and do occur in every state and territory of the U. Addition of Moisture: A sudden flow of water from heavy rain, or rapid snowmelt, can be channeled over a steep valley filled with debris that is loose enough to be mobilized. The water soaks down into the debris, lubricates the material, adds weight, and triggers a flow. Removal of Support: Streams often erode materials along their banks.

This erosion can cut into thick deposits of saturated materials stacked high up the valley walls. This erosion removes support from the base of the slope and can trigger a sudden flow of debris.

Failure of Ancient Landslide Deposits: Some debris flows originate from older landslides. These older landslides can be unstable masses perched up on a steep slope. A flow of water over the top of the old landslide can lubricate the slide material, or erosion at the base can remove support.

Either of these can trigger a debris flow. Wildfires or Timbering: Some debris flows occur after wildfires have burned the vegetation from a steep slope or after logging operations have removed vegetation. Before the fire or logging, the vegetation's roots anchored the soil on the slope and removed water from the soil.

The loss of support and accumulation of moisture can result in a catastrophic failure. Rainfall that was previously absorbed by vegetation now runs off immediately. A moderate amount of rain on a burn scar can trigger a large debris flow. Volcanic Eruptions: A volcanic eruption can flash melt large amounts of snow and ice on the flanks of a volcano. This sudden rush of water can pick up ash and pyroclastic debris as it flows down the steep volcano and carry them rapidly downstream for great distances.

In the eruption of Cotopaxi Volcano in Ecuador, debris flows traveled over kilometers down a valley at an average speed of about 27 kilometers per hour. Debris flows are one of the deadly "surprise attacks" of volcanoes.

Forest Falls debris flow: A home destroyed by a debris flow. Note scattered lumber fragments and insulation. Debris flows can be very dangerous. They can move at high speeds, travel long distances, and fill stream valleys up to meters deep with debris.

Early warning systems are being developed for use in areas where debris flow risk is especially high. One method uses sensitive seismographs to detect debris flows that have already started moving. Another uses radar precipitation estimates and established rainfall intensity-duration threshold values to determine when meteorological conditions are right for flows to occur. Forest Falls debris flow: A yellow pine tree battered by a recent debris flow.