Landslides (landslips, the collapse and flow of earth, mud and rock falls) often occur in times of bad weather (heavy rain, storms), earthquakes, floods, avalanches or melting snow. It is thus as difficult to distinguish between their causes and effects as it is to differentiate between preventive and protective measures.
The damage caused by a landslide varies according to the phenomenon at the origin of the danger and can affect whole regions through, for example, flooding or rivers of mud, or very limited areas as when rock slides or falls occur.
A localised event can also have widespread consequences especially if it disrupts transport links (roads, rail, cable cars) or damages the infrastructure (important buildings, electricity grids, telecommunication networks, conduits, pipeworks and reservoirs for water, gas, toxic and polluting substances).
Landslides can also affect the safety of electricity generating dams and installations (power stations, transformers, etc.) or cause the build up of water behind unstable embankments thus threatening the population and infrastructure lower down in the valley.
2. Preventive and protective measures
Landslides can occur slowly or rapidly. They can generally be predicted by observing areas known to be unstable and by taking into account the meteorological conditions (bad weather).
Preventive measures consist of developments and constructions intended to avoid or at least limit landslides through stabilising work: terracing, drainage anchoring, deep injections into the soil or by the construction of retaining dikes to hold back or divert landslides, tunnels, shafts, etc. Planting trees in unstable areas is also an efficient preventive measure.
As regards long term security measures it is important that legislation on land development requires a systematic appraisal of the potential natural dangers. Before establishing residential areas and granting planning permission for buildings the natural dangers must be taken into account.
These measures will be complemented by the constant monitoring of unstable areas and by an obligation to upkeep forests and vegetation and to maintain high altitude waterways (water falls, silting basins, dikes etc.).
The damaging effects of landslides will primarily be avoided or limited by taking the following preventive and protective measures:
- Monitoring (observatories or specialist institutes) constantly or randomly unstable areas representing a major threat.
- Establishing one or several information and alarm centres to inform the authorities and the public.
- Imposing building restrictions, forbidding people from staying in restricted areas and banning traffic on certain routes (road, rail, etc.)
- Erecting buildings and developing infrastructures that will prevent or limit landslides and protect the population.
- Planning the evacuation of populations eventually at risk.
- Establishing well equipped and trained disaster management and rescue teams which will include geologists.
3. Intervention and rescue measures
As soon as a dangerous landslide is identified and after an assessment of its characteristics the local, regional or national authorities take the protective measures dictated by the situation (observation and warning services, sealing off the area at risk, warning the local population and eventually evacuating all or some of the inhabitants and their belongings). Consultation with experts (geologists, civil engineers) is very important as is knowledge of the damage caused in similar incidents in the past (historical studies of geological hazards).
The political authorities and the governing bodies in charge of the coordinated deployment of civilian and military means of intervention are responsible for managing the protective, search, rescue and rehabilitation operations. If the national capacity for prevention and protection proves insufficient in the light of the probable evolution of the situation, the government of the stricken state can appeal for international emergency assistance. As far as possible, this assistance should be coordinated by the national department in charge of the operations and by non-governmental humanitarian organisations.
4. Instructions for the population
4.1 In case of an imminent risk of landslides
- Respect the laws on land development and environmental protection especially with regard to building restrictions, living restrictions and closure of routes.
- Inform yourself of the protective measures in force, and especially know the alarm signals and evacuation procedures.
- Always keep an emergency kit ready for the family. This should include identity papers, personal documents (medical certificates, vaccination papers, blood type details) and personal medicines. Also pack a portable radio and a torch.
4.2 During the disaster
- Keep calm. Warn the neighbours and help the handicapped, children and the elderly.
- Follow the instructions given by the authorities and rescue teams, especially those concerning the evacuation of people and livestock.
- Listen to the radio but do not use the telephone without good reason (do not overload the lines).
- Turn off the electricity, gas, and the central heating. If there is enough time move valuable objects to the highest and strongest parts of the building.
- Use private vehicles only with the authorisation of the rescue teams (evacuation of the sick and wounded, children and the elderly).
- Close doors, windows and shutters and, if possible, reinforce them.
4.3 After the disaster
- Keep calm, do not panic.
- Check to see if there are any injured people in the vicinity and if possible help them.
- Listen to the radio but do not use the telephone without good reason.
- Check to see if there are any fires in the building and try to put them out.
- Collaborate with the official rescue organs and with the services that are helping the homeless.
- Collaborate in the identification of bodies.