Date Published: May 30, 2024
Summary
With the recent landslide and subsequent deaths in Papua New Guinea, OSAC members with operations in or travelers to countries prone to landslides may seek ways they can protect their organization or travelers in the event of this type of disaster. OSAC created this report to assist members with natural disaster emergency planning.
Landslides: The Basics
What is a Landslide?
According to the U.S. Geological Survey (USGS), a landslide is defined as a “movement of a mass of rock, debris, or earth down a slope.” Landslides include several types of land movement, including flowing, spreading, toppling, sliding, and falling.
Why do They Occur?
Landslides occur due to several reasons, several of which are related to a mass of the earth being agitated by water, including rainfall, snowmelt, changes in ground water or water level, and stream erosion. They may also be brought on due to volcanic activity, earthquakes, or other events. Landslides that occur under water, known as “submarine landslides,” can precipitate tsunamis.
Where do They Occur?
Unlike other disaster events, such as earthquakes, cyclones, or tsunamis, landslides are not often distributed in specific geographic areas. Landslides can occur in areas across the world, especially those that can receive significant rain or snowfall and have sloped terrain. As of 2018, regions with the highest number of landslide-caused fatalities were “in the mountains of Asia and Central and South America, as well as on steep islands in the Caribbean and Southeast Asia.”
Recent Case Study: Papua New Guinea (May 2024)
On May 24, a large landslide took place in Enga province, roughly 370 miles northwest of the capital Port Moresby. Initial estimates placed the death toll at more than 100, however counts vary on an updated tally: one approximation remains around 670, another at 160, while the Papua New Guinea (PNG) government has assessed more than 2,000 people may have been buried alive. Yambali village, where the landslide occurred, is home to almost 3,900 people; 70,000 people in the area have been impacted by the disaster. Papua New Guinea’s Prime Minister James Marape blamed “extraordinary rainfall” for the landslide, in which parts of a mountain collapsed, submerging the area in 20-26 feet of rubble.
As a result of the disaster, power lines were down and water was inaccessible in the affected area. Concerns have been raised as well about disease outbreaks “amid warnings of further landslides.” The head of the International Organization for Migration’s mission in the country noted his “biggest fear at the moment is corpses are decaying, ... water is flowing and this is going to pose serious health risks in relation to contagious diseases.”
Tips for a Landslide Event
For travelers heading to or security managers planning travel for locations with a high risk of landslides, consider the following tips before, during, and after a landslide event.
Before a Landslide
- Understand the overall risk of landslides; stay abreast of weather reports and local forecasts, particularly those forecasting heavy rain or snow in a sloped area (mountainous or hilly regions).
- For an accomodation, move bedrooms upstairs; move high occupancy areas to the downhill side of a building.
- In mudflow areas for an office, site, or accommodation, create channels or deflection walls that can direct the flow around buildings.
- Evacuate the immediate area if possible.
- To prepare for an event in which an accommodation is no longer habitable, consider preparing a go-bag if evacuation becomes necessary. Include water and medicine in the event potable water supplies are affected and/or disease outbreaks become a concern.
- Curl into a tight ball and protect your head if escape is not possible.
During a Landslide
- Don’t move towards an active landslide.
- Evade the threat vertically by moving upstairs.
- If possible, move to interior areas of the building (preferably to unfurnished areas).
- Open downhill windows and doors allowing debris to escape.
- Listen for any unusual sounds that might indicate moving debris, like trees cracking or boulders knocking together. A trickle of flowing or falling mud or debris may precede larger landslides. Moving debris can flow quickly and sometimes without warning.
- If close to a stream or channel, remain alert for any sudden increase or decrease in water flow and change from clear to muddy water.
After a Landslide
- Stay away from the landslide area, as additional landslides may occur.
- Monitor for flooding or flooding conditions.
- Check the building’s foundation and surrounding area for damage to help assess the safety of the area.
- If caught in landslide debris, continue to move and make noise to alert rescuers.
Resources
Several resources may be useful to OSAC member while planning travel. While this is not an exhaustive list, it may serve to at least aid in the preparatory stages of travel planning.
- Resource Watch, part of the World Resources Institute, maintains this live (updates every 30 minutes) Landslide Hazard Assessment for Situational Awareness (LHASA) map from NASA, which plots areas around the world with either moderate or high landslide hazard levels. The data displayed on the map, which is sourced from NASA and is “based on landfall-inducing precipitation on susceptible land,” represents a comparison between the Global Precipitation Measurement (GPM) mission’s recent precipitation data from the prior seven days to the long-term precipitation record from the Tropical Rainfall Measuring Mission’s (TRMM) Multisatellite Precipitation Analysis (TMPA).
- The USGS operates a Landslide Hazards Program, with a webpage hosting links to general information, as well as data, maps, and other web tools related to landslides.
- NASA’s Landslide Viewer plots historical data from previous landslides across the world and “contains more than 11,500 reports on landslides, debris flows, rock avalanches, etc.”
- The Global Landslide Detector, while similar to NASA’s Landslide Viewer, illustrates recent landlsides around the world with data sourced from Twitter.
- Another landslide project from NASA, the Semi-Automatic Landslide Detection (SALaD), employs image analysis and machine learning to “detect landslides from optical imagery.” The code can be downloaded here.
Additional Information
For more information on this topic, please contact OSAC’s regional teams.
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