Earthquake Measured

By The Richter Scale

Engineers tell American Ingenuity that wind forces are more severe than earthquake forces.  Because Ai domes have gone through Hurricane Katrina and Hurricane Andrew with no structural damage, and because of a load test and computer simulation (which can be seen on Ai's CD or DVD), American Ingenuity knows the Ai dome can withstand earthquakes of any magnitude.  The following information came from Michigan Technological University web site: www.geo.mtu.edu/UPSeis/intensity.html

The magnitude of most earthquakes is measured on the Richter scale, invented by Charles F. Richter in 1934. The Richter magnitude is calculated from the amplitude of the largest seismic wave recorded for the earthquake, no matter what type of wave was the strongest.

The Richter magnitudes are based on a logarithmic scale (base 10). What this means is that for each whole number you go up on the Richter scale, the amplitude of the ground motion recorded by a seismograph goes up ten times. Using this scale, a magnitude 5 earthquake would result in ten times the level of ground shaking as a magnitude 4 earthquake (and 32 times as much energy would be released). To give you an idea how these numbers can add up, think of it in terms of the energy released by explosives: a magnitude 1 seismic wave releases as much energy as blowing up 6 ounces of TNT. A magnitude 8 earthquake releases as much energy as detonating 6 million tons of TNT. Pretty impressive, huh? Fortunately, most of the earthquakes that occur each year are magnitude 2.5 or less, too small to be felt by most people.

The following information came from the Central U.S. Earthquake Consortium's web site www.cusec.org

Earthquakes with magnitude of about 2.0 or less are usually called microearthquakes; they are not commonly felt by people and are generally recorded only on local seismographs.

Earthquakes with magnitudes of about 4.5 or greater--there are several thousand such shocks annually--are strong enough to be recorded by sensitive seismographs all over the world.

Great Earthquakes with magnitudes of 8.0 or higher, the 1964 Good Friday earthquake in Alaska. On the average, one earthquake of such size occurs somewhere in the world each year. Although the Richter Scale has no upper limit, the largest known shocks have had magnitudes in the 8.8 to 8.9 range. Recently, another scale called the moment magnitude scale has been devised for more precise study of great earthquakes.

The Richter Scale is not used to express damage. An earthquake in a densely populated area which results in many deaths and considerable damage may have the same magnitude as a shock in a remote area that does nothing more than frighten the wildlife. Large-magnitude earthquakes that occur beneath the oceans may not be felt by humans.

The following information came from Flash, Federal Alliance for Safe Homes whose web site is www.flash.org

What is an Earthquake? An earthquake is a sudden, rapid shaking of the Earth caused by the breaking and shifting of rock beneath the Earth's surface. This shaking can cause buildings and bridges to collapse; disrupt gas, electric, and phone service; and sometimes trigger landslides, avalanches, flash floods, fires, and huge destructive ocean waves.

Withstanding an Earthquake: If the earthquake occurs in a populated area, it may cause many deaths, injuries and extensive property damage. Here are some helpful tips to protect your family and your home.

Before an earthquake strikes:

• Plan and hold earthquake drills for your family. Choose a location where family members will meet if separated during the quake.
• Make your home safer. Strap water heaters, appliances and TVs to wall studs. Secure pictures, mirrors, and ornaments to the wall with appropriate fasteners. Know where and how to shut off electricity, gas, and water services.
• Assemble disaster/survival kits to last 72 hours for each person in the house. Check with local emergency managers for additional tips and safety training.

During an Earthquake:

• Keep Calm. Expect the earthquake to last from a few seconds to a few minutes.
• If indoors, stay there until the shaking stops.
• Make sure to drop down to the floor and take cover under a sturdy piece of furniture or an interior wall. Hold onto the furniture and keep your position.
• If outdoors, move into an open area away from trees, buildings, utility wires, or signs. Stay in the open until the shaking stops.

After an Earthquake:

• Check for injuries. Don't move injured persons unless they are in immediate danger.
• Turn on your TV or radio for emergency information and instructions.
• Check utilities for gas and/or water leaks, or broken electrical connections. Be prepared to turn off utilities in the event they are damaged.
• Clean up medications, cleaning products, and/or flammable liquids. Check food and water supplies. Open cabinets carefully, to avoid objects falling out.

More information on earthquake safety is available through the Central U.S. Earthquake Consortium. Their web site is www.cusec.org