Landslide Rescue: Key causes, warning signs, rescue methods, and safety tips for efficient and effective disaster response.

Main Causes of Landslides

Here is a simple explanation of the main causes of landslides:

• Heavy Rain, Prolonged Rain, and Snowmelt
  • What happens: Heavy or prolonged rainfall and melting snow increase soil moisture, making the ground heavier.
  • Why it’s a problem: When the soil absorbs too much water, it becomes heavy and prone to collapsing, causing landslides or slope failures.

• Earthquakes
  • What happens: Earthquakes shake the ground violently.
  • Why it’s a problem: The shaking destabilizes loose soil and rocks, triggering landslides or cliff collapses.

• Volcanic Eruptions
  • What happens: Lava and volcanic ash flow down mountains during eruptions.
  • Why it’s a problem: Ash can block water drainage and add weight to slopes, increasing the likelihood of collapses.

• Construction Activities
  • What happens: Digging and land modification during construction can destabilize terrain.
  • Why it’s a problem: These activities alter natural stability, making landslides more likely if proper precautions are not taken.

These causes often overlap, increasing disaster risks. For example, heavy rain followed by an earthquake can significantly heighten landslide threats. Human activity combined with natural forces can also result in unexpected disasters.

Common Phenomena Related to Landslides and Terrain Changes

• Cliff Collapse
  • Definition: The surface layer of a steep slope suddenly collapses due to rain, snowmelt, or earthquakes.
  • Features: Happens quickly on steep slopes, leaving no trace of the original shape.
  • Additional Info: Secondary collapses and deeper breakdowns may occur afterward.

• Landslides
  • Definition: A portion of soil slides down due to underground water.
  • Features: Movement is usually slow and may take years, but it can suddenly accelerate.
  • Additional Info: Landslides may trigger cliff collapses or turn into debris flows.

• Debris Flow
  • Definition: A mix of soil, rocks, and water flowing rapidly down a slope.
  • Features: Speeds vary with slope steepness and soil content but can exceed 10 meters per second.
  • Additional Info: Debris flows can occur repeatedly during or after rain, earning the nickname “mountain tsunamis.”

• Deep-Seated Landslides
  • Definition: The collapse extends deeply into the ground and covers a wide area.
  • Features: Triggered by heavy rain or earthquakes, displacing large volumes of debris.
  • Additional Info: A volcanic collapse is referred to as a “volcanic sector collapse.”

• Lava Flows
  • Definition: Molten magma flows across the surface after a volcanic eruption.
  • Features: Faster flows occur with higher temperatures and steeper slopes. Speed typically ranges from a few kilometers per hour.

These phenomena vary by region and geology, requiring tailored prevention and response measures.

Warning Signs Before Landslides and Activity Suspension Guidelines

Recognizing warning signs can save lives. Be vigilant and take appropriate action based on these guidelines:

1. Increase or Cloudiness in Spring Water
   • Explanation: Sudden increases or murkiness in spring water may indicate underground soil movement.
   • Action: Stop activities immediately and move to a safe location.
2. Spring Water Stops Flowing
   • Explanation: If spring water suddenly stops, it could mean underground flow paths are blocked, signaling potential collapses.
   • Action: Halt activities and evacuate to safety without delay.
3. Cracks on the Ground
   • Explanation: Ground cracks indicate weakened soil stability, potentially leading to collapses.
   • Action: Cease activities and prioritize evacuation.
4. Increase in Falling Rocks
   • Explanation: More frequent rockfalls suggest slope instability.
   • Action: Stop activities and retreat to safety.
5. Changes in Stream Flow or Turbidity
   • Explanation: A sudden increase or cloudiness in stream water could mean a landslide upstream.
   • Action: Suspend activities and secure safety.

Monitoring Safety:

• Conduct surveillance from a safe, elevated position, paying close attention to these warning signs. For instance, debris flows moving at 10 meters per second require at least 600 meters of upstream monitoring to ensure safety.

Personal Equipment Guide for Landslide Response

This guide provides a clear explanation of personal equipment needed for landslide response. These items ensure safety and efficiency during operations.

Standard Equipment

• Safety Helmet: Protects the head from falling objects and impacts.
• Kevlar Gloves: Shields hands from cuts and abrasions.
• Safety Harness: Prevents falls during work in high places.
• Boots or Rubber Boots: Protects feet from unstable ground and water.
• Whistle: Used to alert others in emergencies.
• Flashlight: Enhances visibility in dark areas.
• Personal Alarm: Alerts team members during emergencies.

Additional Equipment for Rescue and Excavation

• Goggles: Protects eyes from dust and debris.
• Mask: Prevents inhalation of dust and harmful substances.
• Elbow and Knee Pads: Safeguards elbows and knees from injury.

Equipment for Special Situations

• Rain Gear: Keeps the body dry during rainy conditions.
• Life Jacket: Provides buoyancy during water-based operations.

Equipment for Specialized Manual Digging

• Thick Rubber Gloves: Protects hands and improves handling of wet or muddy materials.
• Duct Tape: Wrap around boot tops to prevent water and mud from entering.

Additional Gear for Emergency, Rescue, and Medical Operations

• Vehicle Rescue Tools: For breaking or unlocking vehicles.
• Water Rescue Gear: Essential for operations in water.

These items form the basics of landslide response equipment. Adjustments should be made based on the specific conditions of the site. Proper use of this equipment ensures safe and efficient operations.

Search Methods

Initial Phase (Surface Search):

1. Visual and Verbal Checks:
   • Inspect the site visually and call out loudly, such as, “Is anyone there?”
2. Silent Time:
   • Ensure silence to detect faint voices or sounds from victims.
3. Manual Debris Removal:
   • Use hands or small tools to remove light debris and check for trapped individuals.

Mid-Phase (Space Search):

1. Use of Advanced Rescue Tools:
   • Employ image cameras or sound detectors to locate individuals under debris.
2. Support and Demolition Tools:
   • Use support equipment to secure the area and demolition tools to expand the search.

Structural or Debris Entry:

• Purpose: Enter structures or debris to locate and rescue survivors.
• Method: Carefully move or remove debris while paying attention to any sounds or movements from survivors.

Full Use of Rescue Technologies and Tools:

• Purpose: Employ all available tools and technologies to effectively find and rescue people trapped in debris.
• Method: Utilize advanced devices such as sound detectors, thermal imaging cameras, and support tools to ensure safety.

Rapid Decision-Making and Coordination:

• Purpose: Ensure quick and efficient operations through fast decision-making and collaboration.
• Method:
  • Decision-Making: On-site commanders evaluate the situation and call for additional resources as needed.
  • Coordination: Use communication devices to share information with other teams and medical staff.

Final Phase (Detailed Search):

Heavy Machinery Use:

• Purpose: Efficiently remove large amounts of debris and locate missing individuals.
• Method: Operate equipment like excavators to clear debris carefully and systematically.

Collaboration with Agencies:

• Purpose: Streamline debris removal and rescue efforts.
• Method: Work closely with local authorities, police, and fire departments to manage debris transport and disposal effectively.

Activity Execution:
Focus on locating missing individuals by thoroughly examining the disaster site. Large-scale debris removal and agency collaboration enhance efficiency and effectiveness.

Angle of Repose

The angle of repose is the steepest angle at which granular materials naturally remain stable. Beyond this angle, materials will collapse.

This concept is critical in geotechnical engineering and helps assess risks in sand or gravel slopes. The actual angle can vary depending on moisture and other factors.

For example, if the angle of repose is 30 degrees, digging 1 meter around a victim requires starting from a horizontal distance of about 1.7 meters to maintain stability. This principle ensures both safety and efficiency during excavation.

By understanding and applying the angle of repose, risks can be minimized, and safety can be enhanced across construction, disaster response, and other fields.

Earth Pressure

Earth pressure refers to the force exerted by soil on underground structures or buried objects. It is a crucial factor in construction and civil engineering. This pressure acts in multiple directions and increases with depth due to the weight of the overlying soil layers pressing down on the lower layers.

There are two main types of earth pressure:

1. At-Rest Earth Pressure: This occurs when the soil is stationary and not moving.
2. Active Earth Pressure: This arises when the soil shifts or deforms.

For example, retaining walls are common structures designed to withstand earth pressure. Their primary purpose is to support soil on one side (typically a slope or hill) and prevent collapse toward the lower side (like a road or building). The pressure exerted on the wall depends on various factors, such as the weight of the soil, wall shape, soil type, and moisture content. Proper design and construction of retaining walls are essential to manage earth pressure and ensure structural safety and durability.

Earth pressure calculations and analyses take into account soil properties (such as cohesiveness, particle size, and density), water content, and external forces like earthquakes. This information helps engineers select materials, determine dimensions, and decide on reinforcement methods, ensuring long-term stability and functionality of structures.

Managing earth pressure is particularly important for underground structures and slope stability. Key measures include:

• Drainage systems to control water accumulation.
• Soil stabilization techniques like compaction or chemical treatment.
• Installation of retaining walls or braces to support soil.

By implementing these measures, the movement of soil and the effects of water can be minimized, reducing the impact of earth pressure on structures.

Basics of Excavation

Excavation work presents various challenges depending on soil type and conditions. Steep excavation angles increase the risk of soil collapse, making preventative measures crucial. Below are basic methods for safe excavation:

1. Widening the Excavation Area:
   • Purpose: To create gentler slopes that reduce the risk of soil collapse or sliding.
   • Method: Extend the excavation boundaries to flatten the slope, thereby increasing soil stability.
2. Enhancing Soil Stability:
   • Water Management: Control moisture levels, as excess water weakens soil cohesion. Reducing moisture helps the soil compact and stabilize.
   • Support Structures: Use timber, metal props, or retaining walls to hold the soil in place and prevent collapse.
3. Temporary Retaining Measures:
   • Purpose: To provide short-term support during small-scale excavation.
   • Method:
     • Sheet Piling: Driving steel sheets into the ground.
     • Wood or Bamboo Barriers: Temporary supports made of natural materials.
     • Fabric Barriers: Using woven materials to stabilize soil temporarily.

Temporary Soil Retaining Measures

Soil retaining structures are used to prevent excavation surfaces from collapsing. During landslide rescues, emergency responders may use simple structures, such as plywood panels (commonly called conpane), to manage soil pressure or prevent surrounding soil from flowing into the excavation. These temporary measures are referred to as temporary soil retaining measures.

Typical methods include sandbags, sheet piles, or H-beams, but for rescue operations, a simpler method using plywood and steel pipes is often employed. The strength of these measures varies depending on soil conditions, moisture levels, and the presence of roots or debris, so constant monitoring and adjustments are crucial.

Key Materials Used

1. Steel Pipes: Used as support posts for retaining soil.
   • Equipped with a conical tip for easier driving into the ground.
   • A top cap is added to prevent deformation during hammering.
2. Plywood (Conpane): Panels used to block soil inflow.
   • Standard dimensions: 90 cm length for plywood, 150 cm for steel pipes.
   • Plywood is driven approximately 40 cm into the ground.

Installation Process and Precautions

• Initial Steel Pipe Installation:
  • Use a small hammer to drive the steel pipe to shoulder or chest height.
  • Switch to a larger hammer to secure the pipe’s position.

• Setting the Plywood:
  • Drive the steel pipe vertically and place the plywood in position.
  • Hammer the pipe until the red marker tape is no longer visible to confirm proper depth.

• Installing Opposite Steel Pipes:
  • Drive a second steel pipe on the opposite side to secure the plywood between them.
  • Use two pipes and rope for stability.

• Simultaneous Excavation and Plywood Placement:
  • Gradually excavate while placing the plywood panels.
  • Avoid forcing the installation; maintain proper strength and alignment.

• Checking Steel Pipes in the Ground:
  • Ensure the pipes are embedded 30–40 cm into the soil, depending on soil conditions.

Approaches for Slopes and Flat Areas

• Slopes:
  Place retaining structures on the uphill side to reduce soil pressure and prevent further soil inflow.

• Flat Areas:
  Use plywood panels to surround the excavation from all sides, countering pressure from every direction.

Other Precautions

• Longer steel pipes may be necessary for certain soil types or slopes.
• Maintain constant supervision and adapt measures to the site’s conditions.

Rescue Activity Procedures (Example)

• Initial Phase of Rescue Activities
  • Assess Surroundings:
    Ensure the safety of the rescue team and establish secure zones.
  • Create a Stable Work Area:
    Use plywood (conpane) to prevent further collapse. On slopes, stabilize the footing with sandbags.
  • Identify the Victim:
    If part of the victim is visible, excavate soil around their face and chest to relieve pressure that could impede breathing.
    Secure the victim with a safety harness.

• Excavation Activities
  • Plan the Rescue:
    Assess the victim’s condition and determine an excavation strategy.
    Begin digging 1.5–2 meters away from the victim if buried to a depth of 1 meter or more.
  • Excavate the Area:
    Expand the excavation area to reduce soil pressure.
  • Special Measures for Upright Burials:
    Use temporary retaining measures to stabilize the area.
  • Precautions:
    Avoid disturbing obstacles around the victim during digging.

• Extracting the Victim
  • Handling the Victim:
    When soil has been cleared to knee level, carefully free their legs.
    If both legs are buried, focus on one leg first, then free the other.
  • Managing Excavated Soil:
    Ensure soil is moved at least 3 meters away from the victim to avoid obstructing rescue operations.
  • Soil Removal Methods:
    Rotate personnel and plan the direction of soil removal.
    Use conveyor belts, bucket relays, or plywood to efficiently transport soil.

Important Considerations for Soil Storage Locations

• Choose a location far enough from the victim and the rescue operation to prevent interference.
• Evaluate the site carefully to ensure it supports smooth rescue progress.

By following these guidelines, rescue teams can perform safe and effective operations, minimizing risks and improving outcomes.

Guidelines for Using Heavy Equipment (Drag Shovel)

The following outlines safe and efficient practices for using drag shovels during rescue operations.

1. Personnel Deployment

• Command Supervisor (Platoon Leader):
  • Should be familiar with the characteristics of heavy equipment and ideally certified in construction machinery operation.
  • Responsible for overseeing the operation, ensuring coordination, and enforcing safe working policies.
• Operator:
  • Should hold qualifications under labor safety and health regulations.
  • Operates the machine according to the manual and ensures safe handling.
• Guidance Personnel (Marshal):
  • Should have knowledge of heavy equipment and ideally be certified in construction machinery operation.
  • Directs the machine’s movements from a safe position and works closely with the command supervisor and safety monitor.
• Safety Monitor (Safety Manager):
  • Should also have knowledge of heavy equipment and be certified.
  • Monitors safety conditions and guards against secondary accidents.

2. Signals

• The machine must operate under the guidance and signals of the marshal.
• Confirm signal protocols in advance to ensure mutual understanding and smooth operations.

3. Coordination with Other Units

• Sharing Work Areas:
  • When collaborating with other teams, clearly communicate hazards and procedures beforehand to ensure safe and efficient work.
• Borrowed Equipment:
  • When using heavy machinery not owned by the fire department, understand its specific characteristics and operate it safely.
• Requesting Heavy Equipment:
  • When using machinery from other units, confirm operational plans and safety management protocols in advance.

4. Safety Management

• Prohibit entry within the working radius of the equipment.
• Supervisors, safety monitors, and marshals must remain outside the operational radius and in safe locations.
• Follow safety standards and ensure operators maintain awareness of blind spots during operations.

5. Other Considerations

• Review past accident cases involving heavy equipment to improve safety measures and prevent injuries.
• Adhering to these guidelines ensures the safe use of heavy equipment while enhancing the efficiency of rescue operations.

Reference page: What is Trench Rescue?Trench rescue is the process of rescuing individuals buried due to excavation collapses or landslides. The goal is to conduct the rescue while stabilizing the surroundings to prevent further collapse and secondary disasters.In the United States, approximately 1,100 workers are seriously injured, and around 100 workers die each year from trench or excavation-related accidents.

References　National Fire Protection Association (NFPA)

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