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Earthquake

Why Think About Earthquakes in The Cayman Islands?

Why Think About Earthquakes in The Cayman Islands?

The Cayman Islands lie close to the boundary zone of the Caribbean and North American tectonic plates. There are two different types of plate interactions close to the Cayman Islands; there is a short spreading centre (divergent plate boundary) south and west of George Town, where the two plates pull away from each other causing magma to come up through the divide, it then cools and creates new crust.  The other plate interaction is a transform boundary (strike-slip), where the plates slide past each other. Both of these plate interactions are known to generate earthquakes.

The Cayman Islands lie close to the boundary zone of the Caribbean and North American tectonic plates. There are two different types of plate interactions close to the Cayman Islands; there is a short spreading centre (divergent plate boundary) south and west of George Town, where the two plates pull away from each other causing magma to come up through the divide, it then cools and creates new crust.  The other plate interaction is a transform boundary (strike-slip), where the plates slide past each other. Both of these plate interactions are known to generate earthquakes.

On January 28, 2020 a 7.7 Magnitude Earthquake occurred with the epicenter being 80 miles (130 km) ESE of Cayman Brac. Another significant earthquake occurred on 14 December, 2004 and while this earthquake was much less strong that the 2020 event, but it was much closer with the epicenter just 20 miles south of George Town, Grand Cayman. Both of these events were associated with (left-lateral) movements on the transform plate interaction between the North American and Caribbean plates. There is the potential for us to be affected by a major earthquake.

 

USGS

 

What to Expect in an Earthquake

During an earthquake, the ground moves like waves on the ocean. The actual movement of the ground, however, is seldom the cause of injury or death. Most injuries and deaths are caused by the collapse of structures, falling masonry, and other objects. Injuries are commonly caused by:

  • Structures collapsing, falling blocks, walls, poles, roofs, ceiling plaster, light fixtures and pictures
  • Flying glass from broken windows
  • Overturned bookcases, wall units, filing cabinets, and other heavy furniture
  • Fires from ruptured gas and broken electrical lines (this danger may be aggravated by a lack of water due to broken water mains)
  • Fallen power lines
  • Vehicular accidents

Earthquake Precautions

Although earthquakes strike without warning, there are many actions that can be taken to reduce their impact. It is important that some of these precautions be taken before an earthquake occurs.

Before an Earthquake

  • Ensure your building meets the requirements of the building code. This will help make it earthquake resistant.
  • You can mitigate non-structural hazards in your building:
  • Bolt down water heaters and gas appliances.
  • Place large and heavy objects on lower shelves.
  • Securely fasten shelves, heavy furniture and filing cabinets to walls; computers should be attached to desks.
  • Bottles, glass, china, and other breakables should be stored locked cabinets; all cabinets should be kept locked.
  • Overhead lighting fixtures, such as chandeliers and other suspended lighting, should be securely anchored and covered.
  • Know where and how to shut off electricity, gas and water at main switches and valves.
  • Practice earthquake drills regularly, so you know what to do in an earthquake.

Have on Hand

  • Flashlights and battery-operated radios in case power is cut off
  • Fire extinguishers
  • First Aid kit
  • Emergency supplies of food and water

During an Earthquake

  • Stay calm — think through the consequences of any action you take.
  • If you are inside, stay inside. Take cover under a heavy desk, table, bench, in a reinforced doorway, or a corner. Evacuate by stairway when the shaking stops. Never use elevators to evacuate after an earthquake.
  • If you are outdoors, stay outdoors. During earthquakes, many injuries occur as people are entering or leaving buildings. Move away from buildings, utility wires, glass, hanging signs and other objects which may fall and cause injury. Get to an open space and stay there until the shaking stops.

Duck, Cover and Hold

Practice the Duck, Cover and Hold procedure until it becomes second nature.

  • Duck – get under a sturdy piece of furniture, making yourself into a little ball (do not duck under beds or other objects that could collapse).
  • Cover – keep your head and eyes protected from falling or flying objects. Cover your head with one hand.
  • Hold – with your other hand, hold onto the piece of furniture. If it moves, move with it. Stay under shelter until you are sure the shaking has stopped.

If you cannot shelter under furniture, move against an interior wall if you are indoors, duck, put your arms over your head and across the back of your neck for protection.

If you are driving when an earthquake starts, slow down carefully and come to a stop in an area free of hazards. When you move off after the shaking stops, proceed carefully because there could be fallen trees, poles or splits and sinkholes in the road.

After an Earthquake

  • Following an earthquake, persons who are in strong, elevated buildings such as offices should remain in the buildings unless there are clear signs of structural failures. The advice for persons in single story buildings along the coastline or in low lying areas is that following a strong earthquake they should evacuate the building and seek higher ground or ascend to the upper floors of strong, elevated buildings to minimise the risks associated with a potential tsunami.
  • EXPECT AFTERSHOCKS. Although most of these are smaller than the main shock, some may be large enough to cause additional damage and damaged buildings to collapse.
  • If you are on the coast and you feel a long and a strong earthquake, do not wait for a notification, move inland or to higher ground in case there is a tsunami.
  • WEAR STURDY SHOES to avoid injury from broken glass and debris.
  • CHECK FOR INJURIES (if a person is bleeding, put direct pressure on the wound, use clean gauze or cloth if available; If a person is not breathing administer CPR; DO NOT attempt to move seriously injured persons unless they are in further danger of injury; COVER injured persons with blankets to keep warm; SEEK medical help for serious injuries
  • CHECK FOR HAZARDS
    • Fire hazards--put out fires in your home or neighborhood immediately, call for help;
    • Gas leaks--shut off main gas valve ONLY if you suspect a leak because of broken pipes or odor;
    • Electrical --Shut off power at the control box if there is any danger to house wiring;
    • Downed or damaged utility lines--do not touch downed power lines or any objects in contact with them. Report damage to the appropriate utility companies;
    • SPILLS--clean up any spilled medicines, drugs, or other harmful materials such as bleach, lye, gas;
    • FALLEN ITEMS--beware of items tumbling off shelves when you open doors of closets and cupboards;
    • CHECK FOOD AND WATER SUPPLIES--Do not eat or drink anything from open containers near shattered glass; If power is off, plan meals to use up foods that will spoil quickly or frozen foods (food in the freezer should be good for at least a couple of days;
    • Don't light your kitchen stove if you suspect a gas leak; USE BBQ or camp stoves, outdoors only for emergency cooking;
    •  If your water is off you can drink supplies from water heaters, melted ice cubes or canned vegetables (AVOID drinking water from swimming pools --it may have too many chemicals in it to be safe.)DO NOT use matches, lighters, camp stoves or barbecues, electrical equipment, appliances UNTIL you are sure there are no gas leaks. They may create a spark that could ignite leaking gas and cause an explosion and fire
  • DO NOT use your telephone, EXCEPT for a medical or fire emergency. You could tie up the lines needed for emergency response. If the phone doesn't work send someone for help
  • DO NOT expect firefighters, police or paramedics to help you. They may not be available.
  • DO a head count to ascertain if anyone is missing; report missing persons to the emergency services.
  • Never re-enter a building after an earthquake until you are informed to do so by the authorities.
  • Ensure that sewage lines are intact before flushing toilets.
  • Listen to the radio for damage reports and other information.
  • Do not go sightseeing. Keep the street clear for emergency vehicles.

For further information, contact Simon.boxall@gov.ky.

 

 
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