CDEMA Earthquake Readiness - Mitigation of Hazards
Mitigation of Hazards

An earthquake may not actually occur during the childhood of students. However, the earthquake safety lessons they learn will stay with them and be useful in adulthood, both for themselves and to pass on to their children.

Earthquakes are a particular concern for schools with their large concentrations of children in confined spaces, and a relatively low ratio of adults to children. Schools need to ensure buildings are more earthquake-proof, include earthquake preparedness in emergency plans, teach children and staff what to do if an earthquake happens, and keep emergency supplies on hand.

 

The purpose of this guidebook is to assist school district staff, teachers, parents, and students to make their schools safer, and to know what to do before and after an earthquake occurs in their area.

Mitigation of Earthquake Damage and Casualties

The potential damage caused by earthquakes could be greatly reduced through a variety of earthquake mitigation measures. The most common (and effective) mitigation measures are the enforcement of seismic codes, land-use zoning, and engineering works to strengthen existing structures and stabilize hitherto unstable ground. Some measures are applicable to new development while others to existing development. Public education and awareness that influence human behaviour and settlement patterns are also important. However, a unified code for building earthquake-resistant restructures has not been adopted by Caribbean Community states.

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Settlement Patterns, Human Behaviour and Earthquake Vulnerability 

Notwithstanding the seismic characteristics of affected structures, human behaviour during an earthquake is a major factor in determining the extent of initial and directly-related casualties.

As earthquake vulnerability is in part a function of the interaction between structural and human behaviour, it is reasonable to assume that earthquake vulnerability is generally greater in urban centres. "Unmanaged urban growth and human settlements are a problem since housing is often constructed without appropriate regard to building codes, zoning laws and environmental standards. This tends to result in highly vulnerable structures often built on marginal lands, hillsides or floodplains.” (Baastel, 2007).

Search and Rescue (SAR) Response

The potential for additional follow-on casualties, once the shaking is over, is also dependent on human behaviour during the Search and Rescue response. 

The two most important variables that determine the level of additional casualties during the response to an earthquake are:

 

• the speed or efficiency of finding and
   rescuing trapped individuals, and

• the care and assistance provided to
   affected people.

The majority of trapped victims will be rescued by the initial efforts of unaffected people in the immediate area, assisted where possible by local first responders. The efficacy of this first reaction could depend on the level of earthquake awareness of the general population, plus the training and equipment-support for first responders (Baastel, 2007). 

 

National Disaster Offices have concerns about the role of ordinary citizens in search and rescue efforts. Members of the public may either have a crucial role to play in these efforts (skilled in search and rescue, civil engineering, equipment supply) or may obstruct emergency personnel in the execution of their duty. It is important to gather from the NDO what its requirements may be in the event that buildings or infrastructure collapses from earthquakes.

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The Unique Characteristics Of Earthquakes Make It A Very Difficult Natural Disaster To Prepare For:

Rapid on-set event - Earthquakes are rapid on-set events that occur with little, if any, warning.

Ground Shaking - The magnitude of the earthquake at its point of origin determines the amount of energy released. Both the distance and the type of materials (rock type, ocean, etc) which earthquakes travel through affects the seismic waves and thus, the intensity of the same earthquake could differ at two different locations. The duration of the shaking is another contributing factor to the destructiveness of the event, as is the nature of the ground on which affected structures are located.

Surface Faulting - Ground displacements in areas of active fault lines could result in damage to life-lines. Roads, pipelines, water mains and sewer systems could be severed if they stretch across fault lines, unless mitigation measures have been implemented.

Induced Ground Failures - Ground shaking could trigger landslides or rock falls, which in turn could result in casualties or damage to structures.

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Seismic Hazards in Schools

Seismic hazards can be considered in three categories:

  1. Classroom hazards that can be corrected by students and teachers;
  2. Neighbourhood hazards that possibly cannot be corrected, but can be taken into account in the response plan.
  3. Maintenance hazards that require special skills for correction.

The following are suggestions on how to eliminate seismic hazards:

Classroom Hazards: 

  • Heavy loose objects that could cause injury should not be stored on shelves or hanging where they can fall more than one meter above the floor. If heavy objects cannot be moved, attach them to the desk or table they are sitting on with a heavy duty hook-and-loop fastener, such as Velcro. If necessary, add lips to shelves to keep them from sliding off.

  • Hazardous materials such as those that may be found in science laboratories and industrial education shops must be stored in an approved cabinet or a designated storage room.

  • Aquariums should be located away from seating areas.

  • Heavy items such as pictures and mirrors should be moved away from sleeping and sitting areas.

  • Wheels on rolling carts such as a TV cart should be locked.

  • Hallways and exits should be kept clear of objects that might fall and make it difficult to get out of the building. 

Neighbourhood Hazards

 

The purpose of identifying neighbourhood hazards is to assist in the planning of post-earthquake procedures such as the designating of assembly areas. It may be impossible to reduce such hazards, but to know what can happen is the basis of a good earthquake safety program. This list may be compiled with assistance from the local municipal police or fire authorities, utility companies, and federal or provincial emergency program personnel:

 

  • Facilities containing hazardous materials (e.g., gas stations)

  • High-voltage power lines

  • Major traffic routes (e.g., freeways and railway lines)

  • Major oil and natural gas pipelines

  • Transformers and underground utility vaults

  • Multi-storey buildings vulnerable to collapse

  • Water towers

  • Landslide areas

  • Flooding from collapsed dams, or dykes

  • Exposure to tsunamis (i.e. seismic sea waves).

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Mitigation of Maintenance Hazards

  • Bolt the building to the foundation if necessary.

  • Repair any deep cracks in ceilings or foundations.

  • Repair or replace defective electrical wiring and leaky gas connections.

  • Replace inflexible utility connections with flexible ones.

  • Bolt down and secure water heaters, gas appliances, refrigerators, and other appliances.

  • All industrial education machine tools and equipment must be securely fastened to the floor or wall.

  • All kitchen equipment in teaching kitchens and home economics rooms must be secured against rolling or overturning.

  • Exhaust hoods should be secured to the building's structure.

  • Lockers, shelves, cupboards, bookcases, filing cabinets, storage racks, pianos, etc., exceeding one meter above the floor should be secured to structural member(s) of a wall or partition.

  • Clocks, projection screens, TV monitors, heavy pictures, light fixtures, and similar appendages should be secured to a structural member of a wall or partition.

  • Install latches on cabinet doors.

  • Move beds and cribs away from windows and lock their wheels if possible.

  • Unreinforced masonry of any kind should be removed, if possible, or braced.

  • Covered play areas and other free-standing structures may be braced at low cost, in consultation with a structural engineer.

  • Appendages over access doors or footpaths should be removed, if practical; alternatively, check the support and possibly provide additional fixing to structure.

  • Tile roofs should be checked, and loose pieces reaffixed; a restraining board may be fitted at the eaves; in the long-term, replace with metal roofing or asphalt shingles.

  • Ceiling spaces should be checked to ensure that all components are firmly secured to the floor or roof structure above.
     
  • Brace overhead light fixtures.

  • Glass lighting fixtures should be replaced with plastic.

  • Plain glazing in hazardous locations should be replaced with tempered glass, wired glass, or polycarbonate sheets.

  • Old slate chalkboards or marble toilet partitions should be replaced with modern fixtures.

  • Heavy gymnasium equipment should be secured to the structure or braced against overturning.

It is recommended that, prior to assessing hazards throughout the school, a plan(s) of the school and grounds are prepared. Such a plan(s) will:

 

 

  • Enable the location of all hazards to be shown.

  • Assist in the preparation of emergency response procedures.

  • Enable evacuation routes to be shown.

  • Identify the location of safe assembly areas.

  • Enable the location of the following items to be shown:
     
    • Power line routes (overhead and underground)

    • Gas, water and sewer lines

    • Outside faucets

    • Mains switches and shut-off valves

    • Mechanical equipment

    • Hazardous materials storage

    • Fire extinguishers

    • First aid equipment

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Aftershocks can follow an earthquake on and off for days or weeks.