User Tools

Site Tools


earthquake

Earthquakes are tremors caused by the shifting of tectonic plates beneath the earth's surface, they can very in severity from mild shaking to tremors so powerful they topple buildings and destroy infrastructure.

Earthquake.jpg

Understanding Earthquakes

Not everyone lives in an active earthquake zone such as the West Coast of the United States. However you would be surprised to find out that places far away from the coastal plates do have earthquakes on rare occasions. For example the New Madrid Fault Zone along the Mississippi River produced two Great Quakes (magnitude 8.2+) in 1811 and 1812. In 1882 there was a Major Quake (magnitude 5.0 - 7.9) in the Rocky Mountain Front Range of Colorado that knocked down chimneys and caused other damage to buildings in Denver. There have been earthquakes in Utah, Illinois and New York, among others, and these states will have them again.

Due to their rarity earthquakes in areas not considered to be on major faults will likely cause more deaths, injuries and damage to buildings since these areas are seldom prepared for them.

Preparing for an Earthquakes

Preparing for an earthquake, like so many other disasters, requires you to store food and water in the case of interruption of supplies. Earthquakes differ in that they offer no warning whatsoever and that preparation has more to do with your home or office's construction, layout, and location.

Food

Food storage should be a major part of any disaster preparation plan, and earthquakes are no exception. While earthquakes have little effect on a rural landscape, they can devastate infrastructure in an urban area interrupting the food supply.

Water

Water should always be stored for any disaster. Earthquakes can break underground plumping systems, causing tap water to become unavailable for quite some time.

Preparing Your Home

The greatest challenge to earthquake survival is to preserve your life, limbs, and property. The most effective way to prepare for this is to choose a home that can withstand earthquakes. The primary considerations for this will be location, construction, and internal layout.

Type of Home

Most people in America live in single family dwellings that are of wood frame construction. This actually is the ideal building as it is the most stable construction type without going to a custom designed earthquake resistant home. The worse type of building to live in is an old multi-storied brick building from the 19th - mid 20th Centuries. Termed “unreinforced masonry buildings” (UMB's) these tend to crumble and collapse during a major earthquake. A UMB can be easily identified by the deep window wells and the row of bricks set crosswise about every fifth row or so. If you live in one of these old UMB's consider moving as soon as possible.

Apartment dwellers should remember the lessons learned during the Northridge Quake of 1994 where 16 people died in the Northridge Meadows Apartments when they collapsed. The apartments were all in three story buildings before the quake. Since the quake hit at 4:31 AM most of the apartments were occupied and the residents asleep. The quake caused the bottom floor to pancake under the stress of the shaking. When rescuers arrived they were surprised to see that the buildings all stood seemingly intact but only two stories tall. Needless to say that all the deaths were people crushed in their beds when the upper floors came down on them. Those that rolled out of bed before the collapse were trapped in voids (empty spaces) next to the beds and were generally alive to be rescued.

Location

No matter what your type of home you will want to make sure it is located outside of an area where there are buildings above two stories tall. In this way during the earthquake there won't be much to fall on you or your home. Ideally your house should only be one story tall, and built to remain structurally sound during an earthquake.

Damage and Injury Mitigation

Whatever your type of home and its location survey it with “earthquake eyes” to look for threats. That is, go around and think what could break or fall down during a tremor. The most dangerous places in a house are typically the kitchen and the bathroom due to the amount of glass objects located in both. But there are dangers everywhere. Here are some steps you can take to mitigate damage and potential injury:

  • Ensure you house is bolted to the foundation.
  • Strap your water heater tank to the wall with plumbers tape.
  • Reinforce “cripple walls” or other structurally weak areas such as attached garages.
  • Attach paintings, wall hangings and furniture such as bookshelves to the wall with industrial strength velcro to prevent falling over.
  • Use “child proof” safety latches on cupboards and shelf doors where glassware, china, etc. are stored to prevent opening during a tremor.
  • Separately store chemicals that are harmful if spilled or mixed together such as ammonia based window cleaners and chlorine based cleansers.
  • Move any heavy hangings from above chairs or beds where if they fell during a tremor they would cause injuries.
  • Store a pair of shoes, a pair of gloves and a flashlight next to the bed to avoid injury moving around after a quake when the power is out.
  • Store a wrench at or near your gas shut-off valve. Remember, once shut off only the gas company can turn the gas back on safely.

Preparing Your Work

Not every earthquake takes place when you are home in bed. The Loma Prieda Quake of 1989 (aka the World Series Quake) took place at 5:04 PM when most people were either at work or had just left work to join the commute. Again, you can mitigate possible death or injury by looking at what type of building you work in and what preparations have been made to deal with an earthquake. If your employer or building management does not have an emergency preparedness/disaster contingency plan you should assist in creating one if at all possible. Regardless you should have an Office Kit which is a type of BOB in addition to your Every Day Carry supplies.

During the Earthquake

Your response to an earthquake very likely will determine whether you survive or not. The shaking may last from 15-20 seconds in a Minor Quake (magnitude 3.0-4.9), from 20 - 45 seconds in a Major Quake (magnitude 5.0-7.9) and from 45 - 180 seconds in a Great Quake (magnitude 8+). The longer an earthquake lasts the greater the destruction potential and likelihood of building collapse.

The universal instruction for earthquake response is “Stop, Drop & Hold!” That is, you stop what you are doing. Do not move from your location unless you are in a precarious position such as on a ladder, next to a window or other glass, etc. Running outside can get you killed due to falling debris. You drop, preferably beneath a table or next to a bed where a void may be created if there is a collapse and hold on to the object protecting you so it doesn't shake across the room away from you.

It used to be taught to take cover inside the frame of a doorway. This has been modified as doors tend to swing violently back and forth during the quake which may injure anyone sheltering there. Going underneath a table is preferred to sheltering in a doorway.

If you are in a vehicle slow down and pull over to a point of safety. During earthquakes freeways and bridges are very dangerous locations to be on. Never stop underneath a beam for a bridge or overpass. Stop under a void if on a lower bridge deck or stop over a support if on a upper deck of a bridge. Stay in your vehicle and do not get out until after the quaking stops. Proceed carefully off the bridge or overpass watching for collapsed sections.

Other risk factors while driving during an earthquake are power/light poles falling, downed wires and of course, other drivers. Watch out for these factors as well when slowing and pulling over to a safe spot.

Earthquake Aftermath

Immediately after an earthquake the first thing to do is perform a self-assessment. You check yourself as you may not realize the extent of any injuries you have. Also you cannot care for others if you have untreated wounds. If you are in a collapsed building and are unable to extricate yourself you have to conserve your strength and fortify your will to last until rescue comes for you. Audible communication that doesn't exhaust you, such as praying aloud or talking to yourself, is recommended to make it easier for rescuers to find you.

If you are not trapped and are able to extricate yourself prepare to assist others. First make sure your hands and feet are protected. When working as a rescuer, even if only for you own family, don safety shoes and work gloves if possible. If available also use some sort of eye protection and a hard hat. These should be part of your emergency supplies.

The next priority is to move outside to a safe location bringing all ambulatory survivors with you, whether family (if at home) or coworkers (if in the office). Once outside you treat the injured and then perform a building assessment. If the building is safe allow people to reoccupy it.

Look at the building you left for signs of damage that makes it unsafe to reoccupy:

  • Collapsed or pancaked floors - never re-enter unless you are a trained rescuer and part of a team.
  • Collapsed stairwells - signs of structural damage.
  • Leaning walls due to the building tilting (building is prone to collapse during aftershocks).
  • Cracks in load bearing walls at corners of windows and/or doorframes (sign of future collapse).
  • Tilting floors or other signs of a building off of its foundation.
  • Smell of smoke in the building or signs of smoke coming from any part of the structure.
  • Smell of natural gas or other toxic gas in the building (shut off gas at meter and vent).

Typical damage that does not affect structure reoccupancy:

  • Fallen ceiling tiles (typical, clean up issue only).
  • Broken sprinkler pipes (shut off sprinkler main and clean up issue).
  • Broken furniture, mirrors, showers, light fixtures or fallen wall hangings (clean up issue).
  • Loss of water pressure, electricity and/or gas (if shut off*).
  • Note: check gas meter and if gauge is spinning (sign of leak in system) then shut off gas by turning valve 90 degrees with a crescent wrench or other spanner. Only the gas company may turn it back on after the leak is repaired and inspected.

After assessing for initial damage remember that the building will need reassessing following any aftershocks.

Once you have stablized the situation where you are at initiate your disaster preparedness/recovery plan. This may involve sheltering in place/bugging-in or evacuating/bugging-out.

Historic Earthquakes

See Also

References

earthquake.txt · Last modified: 2020/03/12 18:33 (external edit)