Measuring the Power of an Earthquake

The magnitude of an earthquake is a measure of its size and is given a value which does not change regardless of your location.

The intensity of an earthquake has to do with measuring the effect of the shaking, and this value does vary with location.

We always hear the word 'Magnitude' when an earthquake is reported.

Here are some links to give you some information on what is called the Richter Scale, what it is and how it works.

1. USGS – The Richter Magnitude Scale

2. Wikipedia - Richter Magnitude Scale

Are Earthquakes on the Increase?

Not according to the United States Geological Survey. The fact is that as they place more seismograph stations across the world along with improvements in global communications they can monitor more earthquakes. Earthquakes of magnitude 7.0 or greater have remained fairly constant according to their findings. What we need to remember is that out of the great number of earthquakes recorded every year, there are approximately 17 major earthquakes of magnitude 7.0 - 7.9 and one great earthquake of magnitude 8.0 or other in any given year. Have a look here for a report found on AccuWeather about this.

The USGS estimates that approximately several million earthquakes occur every year but that many go undetected because they occur in remote locations. Have a look at their Earthquakes Facts and Statistics page for more information. The USGS locates approximately 50 earthquakes each day making that 20,000 per year.

The predictability of earthquakes seem to vary from not easily predictable to not predictable. Geologists and other professionals measure the pressure on the tectonic plates along the faults which may give them a clue as to if and when an earthquake is likely. Also, scientists are able to 'expect' if not 'predict' an earthquake by studying records that they have of the diverse areas where earthquakes have happened. From what I have read on the USGS site, a magnitude 6.5+ is expected in the Nephi segment of the Wasatch Range in Utah.

Earthquakes cannot be predicted with great accuracy, and the best that scientists can do is make educated guesses based on current and past data, but it remains that its a guess.

Earthquakes themselves rarely cause injuries, in that it is the falling debris from buildings and other structures as well as road accidents that are the main causes and areas where injuries occur.

There are many earthquakes that happen yearly around the globe. The location of the epicenter, the depth and types of land surface features or geological conditions that are affected will determine the extent of the damage caused by the earthquake.

Many are relatively harmless and do little or no damage. In all of the recorded instances of earthquakes happening yearly, the larger more destructive ones are rare in comparison to the whole.

The fact that there is media coverage when a larger earthquake happens may lead us to believe that they are not rare.

Earthquakes may cause the ground to shake for several seconds to several minutes, during which time significant damage may occur to buildings and other structures such as dams and towers.

I would like to add a few things that aren't mentioned in the information below.

1. During an earthquake the majority of injuries and deaths occur as people move around in their homes and try to leave the building during the quake. By doing so they expose themselves to falling furniture and other things within the home, as well as falling brick, glass and other debris if they try to exit the building.

2. Locate before an earthquake any potential troublespots in your locality such as chemical factories, railroads, overpasses and other bridges, power line installations, gas stations and in fine anything else that may pose a threat to your well being.

In the information below it mentions that if it is safe to do so, you may re-enter your home.

However it may be a good idea to check with your insurance company if you plan on getting earthquake insurance, to see what the rules are should the disaster strike.

The insurance company may want to send someone to assess the damages and take photos. Take your own as well but but do not disturb the area if it can be avoided.

Here are some links to help you learn more about earthquakes.

1. USGS - Earthquake Facts

2. USGS - Earthquake Notification Service

3. List of Links: Preparedness Information and Response Agencies

4. BBC Home -  Animated Earthquake Guide


6. CBC - Earthquakes

Earthquakes in Canada

The following information is from the Get Prepared site of the Government of Canada.

For more info on earthquakes

Atlas of Canada

Canadian Hazard Information Service - Earthquakes Canada

In Canada, the coast of British Columbia is the region most at risk from a major earthquake. Other areas prone to earthquakes are the St. Lawrence and Ottawa River valleys, as well as parts of the three northern territories. Approximately 5,000 mostly small earthquakes are recorded in Canada each year. In the past 100 years, at least nine earthquakes in or near Canada have registered a magnitude greater than 7. A few have caused extensive damage. Even a magnitude 6 earthquake could do extensive damage in a built-up area. In fact, a strong quake near one of Canada's major urban areas would likely be the most destructive natural disaster this country could experience.

Earthquake Facts

  • The earth's crust is composed of many large and small segments called tectonic plates. These plates are in constant slow movement. With these movements come small tremors and earthquakes.
  • Shallow crevasses can form during earthquakes due to landslides or other types of ground failures.
  • Buildings do not automatically collapse in earthquakes.
  • Earthquakes cannot be predicted.

What to expect during an earthquake

Small or moderate earthquakes

  • These can last only a few seconds and represent no emergency risk.
  • Ceiling lights may move and some minor rattling of objects may occur in your home.
  • You may feel a slight quiver under your feet if you are outside.
  • If you are close to its source, you may hear a loud bang followed by shaking.

Large earthquakes

  • These can last up to several minutes and constitute a natural disaster if its epicentre is near a densely populated area, or its magnitude sufficiently large for the region.
  • The ground or floor will move, perhaps violently.
  • Whether far away or close to the source, you will probably feel shaking followed by a rolling motion, much like being at sea.
  • If you are far away from the source, you might see swaying buildings or hear a roaring sound.
  • You may feel dizzy and be unable to walk during the earthquake.
  • If you live in a high rise or a multi-storey building, you may experience more sway and less shaking than in a smaller, single-storey building. Lower floors will shake rapidly, much like residential homes. On upper floors, movement will be slower but the building will move farther from side to side.
  • Furnishings and unsecured objects could fall over or slide across the floor.
  • Unsecured light fixtures and ceiling panels may fall.
  • Windows may break.
  • Fire alarms and sprinkler systems may be activated.
  • Lights and power may go off.

Know what to do before, during, and after an earthquake

Before an earthquake: Home Preparedness checklist

  • Go through your home, imagining what could happen to each part of it, if shaken by a violent earthquake. Check off the items that you have completed in this list.
  • Teach everybody in the family (if they are old enough) how to turn off the water and electricity.
  • Clearly label the on-off positions for the water, electricity and gas. If your home is equipped with natural gas: tie or tape the appropriate wrench on or near the pipe, to turn off the gas, if necessary.
  • Repair loose roof shingles.
  • Tie the water heater to studs along with other heavy appliances (stove, washer, dryer), especially those that could break gas or water lines if they shift or topple.
  • Secure top-heavy furniture and shelving units to prevent tipping. Keep heavy items on lower shelves.
  • Affix mirrors, paintings and other hanging objects securely, so they won't fall off hooks.
  • Locate beds and chairs away from chimneys and windows. Don't hang heavy pictures and other items over beds. Closed curtains and blinds will help stop broken window glass from falling on beds.
  • Put anti-skid pads under TVs, computers and other small appliances, or secure them with Velcro or other such product.
  • Use child-proof or safety latches on cupboards to stop contents from spilling out.
  • Keep flammable items and household chemicals away from heat and where they are less likely to spill.
  • Consult a professional to find out additional ways you can protect your home, such as bolting the house to its foundation and other structural mitigation techniques.
  • If you live in an apartment block or a multi-storey building, work with your building manager or condominium board to decide how best to "quake-safe" your unit. Seek advice from professionals (building engineers, emergency preparedness authorities) if you are unsure about what to do.
  • If you live in a mobile home, you can leave the wheels on the mobile home to limit its fall. Or, you can install a structural bracing system to reduce the chance of your unit falling off its supports. Ensure the awning on your home is securely supported and fastened to the unit. For information on the best way to brace your unit, contact your local mobile home dealer or a mobile home owner's association.

Safety Tips

  • Don't shut off the gas unless there is a leak or a fire. If the gas is turned off, it must be turned on again by a qualified tradesperson.
  • Discuss earthquake insurance with your insurance broker. Check your coverage – it could affect your financial ability to recover losses after an earthquake.

During an earthquake

Wherever you are when an earthquake starts, take cover immediately. Move a few steps to a nearby safe place if need be. Stay there until the shaking stops.

If you are indoors: "DROP, COVER, HOLD"

  • Stay inside.
  • Drop under heavy furniture such as a table, desk, bed or any solid furniture.
  • Cover your head and torso to prevent being hit by falling objects.
  • Hold onto the object that you are under so that you remain covered.
  • If you can't get under something strong, or if you are in a hallway, flatten yourself or crouch against an interior wall.
  • If you are in a shopping mall, go into the nearest store.
  • Stay away from windows, and shelves with heavy objects.
  • If you are at school, get under a desk or table and hold on. Face away from windows.
  • If you are in a wheelchair, lock the wheels and protect the back of your head and neck.

If you are outdoors

  • Stay outside.
  • Go to an open area away from buildings.
  • If you are in a crowded public place, take cover where you won't be trampled.

If you are in a vehicle

  • Pull over to a safe place where you are not blocking the road. Keep roads clear for rescue and emergency vehicles.
  • Avoid bridges, overpasses, underpasses, buildings or anything that could collapse.
  • Stop the car and stay inside.
  • Listen to your car radio for instructions from emergency officials.
  • Do not attempt to get out of your car if downed power lines are across it. Wait to be rescued.
  • Place a HELP sign in your window if you need assistance.
  • If you are on a bus, stay in your seat until the bus stops. Take cover in a protected place. If you can't take cover, sit in a crouched position and protect your head from falling debris.

AVOID the following in an earthquake

  • Doorways. Doors may slam shut and cause injuries.
  • Windows, bookcases, tall furniture and light fixtures. You could be hurt by shattered glass or heavy objects.
  • Elevators. If you are in an elevator during an earthquake, hit the button for every floor and get out as soon as you can.
  • Downed power lines – stay at least 10 metres away to avoid injury.
  • Coastline. Earthquakes can trigger large ocean waves called tsunamis.

After an earthquake

Stay calm. Help others if you are able.

  • Be prepared for aftershocks.
  • Listen to the radio or television for information from authorities. Follow their instructions. Place telephone receivers back in their cradles; only make calls if requiring emergency services.
  • Put on sturdy shoes and protective clothing to help prevent injury from debris, especially broken glass.
  • Check your home for structural damage and other hazards. If you suspect your home is unsafe, do not re-enter.
  • If you have to leave your home, take your emergency kit and other essential items with you. Post a message in clear view, indicating where you can be found. Do not waste food or water as supplies may be interrupted.
  • Do not light matches or turn on light switches until you are sure there are no gas leaks or flammable liquids spilled. Use a flashlight to check utilities and do not shut them off unless damaged. Leaking gas will smell.
  • If tap water is still available immediately after the earthquake, fill a bathtub and other containers in case the supply gets cut off. If there is no running water, remember that you may have water available in a hot water tank (make sure water is not hot before touching it) and toilet reservoir (not the bowl).
  • Do not flush toilets if you suspect sewer lines are broken.
  • Carefully clean up any spilled hazardous materials. Wear proper hand and eye protection.
  • Check on your neighbours after looking after members of your own household. Organize rescue measures if people are trapped or call for emergency assistance if you cannot safely help them.
  • If you have pets, try to find and comfort them. If you have to evacuate, take them to a pre-identified pet-friendly shelter.
  • Place a HELP sign in your window if you need assistance.
  • Beware of secondary effects. Although ground shaking is the major source of earthquake damage, secondary effects can also be very destructive.
  • These include landslides, saturated sandy soils becoming soft and unstable, flooding of low-lying areas and tsunamis washing over coastlines.

Include this page in your emergency plan

If you live in an earthquake zone in Canada, print this information and include copies in your emergency plan and emergency kit.


Have an Earthquake Bedside Kit prepared in advance.
Preparedness Now - TV Documentary

Some of the government info for the kit is a little corny, so do some research on this site as well as elsewhere to improve upon it.

They give guidelines but much better preparations are possible.
Earthquake Preparedness: Bedside Kit

He mentions jogging shoes, however get something more sturdy if you can.

Some Things to Consider
(quoted from Earthquake Bedside Kit)

"If you are a smoker avoid smoking if you are trapped in your bedroom after an earthquake, in that you may potentially ignite a fire in your room with you trapped in it, and possibly with others of your family trapped in other parts of the house.

Having a fire to contend with while being trapped isn't doing anyone anything good. Also, you may affect your neighbors who may be trapped as well.

If you are using natural gas, or your building does such as in an apartment complex, all the more reason to avoid smoking. And remember to not light candles in such cases and to use non-incendive flashlights to avoid a possible explosion from sparks that may occur as you turn the flashlight on. This occurs within the casing and if you are using the old style incandescent bulbs, they contain an element that heats up to create light."

"If you have a small dog, you can attach a small pinch light (or flashlight) and whistle to his/her collar.

In the event you are trapped anywhere in your house or apartment, your small animal might not be and can easily maneuver around fallen furniture and things and bring you a source of light as well as signaling.

If you try this with a cat, well it might work except cats tend to be more independent than dogs when you call their name, and may or may not come to you if you call them.

If you want you can also place your name, number and address in a small 'pill capsule' that can hang on the collar as well. The reason for this is that perhaps your animal might leave the premises and someone might see the capsule and know someone might be in need of assistance.

Even better is if you use the note and pen in the list to the left, and write information on your current condition and whereabouts and then place it in the capsule. This way anyone finding it will know that it is freshly written and pertinent, and also there is less of a privacy concern than under normal (non emergency) times to have personal information attached to your animals collar.

Having a PSK (personal survival kit) of some sort with you at all times, or having emergency items throughout your house or apartment, may also be an option so you can have things close to you wherever you may be if the quake hits and you are limited in movement."

Drop, Cover, Hold On ?

In North America the construction standards are not the same as say, in Turkey, where structures will react differently to earthquakes.

Have a look at the links that I provide here below for important information.

Earthquake Country Alliance - Drop, Cover, Hold On

Triangle of Life - Snopes

The experts DO NOT recommend using the Triangle of Life, but the Drop, Cover, Hold On approach.

There are too many variables to be able to understand exactly how any builidng will cope with an earthquake, and not all earthquakes are equal. The intensity (magnitude) and duration, movement, depth and geological features where it is felt also have an impact on how and whether the building will hold up or not.

The age of the building, the materials used in its construction as well as the engineering standards among other things make it impossible to predict exactly what will happen.