Earthquakes

Introduction
Earthquakes can be minor events that cause little or no damage to structural buildings, cars, animals, people, and/or nature. Earthquakes can also be severe events that cause major damage to everything and anything within the area being affected. The general idea of an earthquake is that the ground begins to shake while pictures start falling off the walls, car alarms scream, and people run for cover. The general idea is accurate to an extent but there is a lot more happening beneath the Earth's surface than just some shaking. Geologists have spent a number of years studying and attempting to predict future earthquakes to ensure the safety and security of our communities.

Causes
An earthquake is the sudden shaking of the Earth's surface caused by a fault, which is a shift along the Earth's rock. The stress being released by an earthquake may have been accumulated over a long period of time, even hundreds of years. An earthquake's size is called magnitude which is measured by the amplitude or seismic waves. The intensity of an earthquake is calculated by the level of ground shaking and damage to structures, people, animals, and nature.
The U.S. Geological Survey Web site reports the cause of an earthquake as, "Earth scientists believe that most earthquakes are caused by slow movements inside the Earth that push against the Earth's brittle, relatively thin outer layer, causing the rocks to break suddenly." (1988, Noson, Qamar, & Thorsen). The thin outer layer is referred to as plates, and most earthquakes will occur on the rim.

Predictor
The animal behavior factor is based on mostly anecdotal evidence reporting animals have the ability to detect upcoming events that technology or humans can't. It's hard to say whether an animal's unusual behavior always indicates something bad about to happen. Sometimes animal's behavior is unusual even when nothing bad happens. From personal experience when a tornado was about to hit nearby my 8 year old Pomeranian named Foxie was acting very agitated and strange, my other two dogs showed no signs of anything wrong. I don't think the animal behavior predictor is an accurate tool to use for future events such as earthquakes. The rock precursor also doesn't seem to be the best method to predicting future earthquakes. I think the recurrence interval is the most helpful in determining the next earthquake, because it has proven to be mostly accurate. The recurrence interval is an average period of time between earthquakes in a specific area. The recurrence interval is also widely used in predicting floods. I think it's most accurate because scientists can gather data from previous earthquakes from a specific area and calculate when a future earthquake may occur. It's hard to predict when exactly an earthquake will occur, but scientists can detect a possible strain on plates and when a fault might occur. (2004, Ludwin). I think the recurrence interval is reliable and should be utilized for other natural disasters similar to earthquakes.

Measurements
The Richter scale utilizes mathematics to measure the intensity of the ground shaking during an earthquake. The scale measures the amplitude of the waves being produced by an earthquake, such as on a seismograph. (2006, Scales).
The Richter scale can detect small earthquakes but Mercalli cannot.
The Richter scale is more accurate than the Mercalli scale because it's based of mathematics rather than observations.
The Richter scale measures the magnitude of waves to determine the amplitude of an earthquake while the Mercalli scale only bases its findings from people and animal reactions.

The Mercalli scale measures the intensity of an Earthquake by recording reactions of people and animals. The Mercalli scale is based on people's responses during a quake. Were they startled enough during their sleeping or napping period? Did furniture begin to move or pictures fall off the walls? What about structural damage? (2007, Stommel).
The Mercalli scale determines what areas are mostly affected by an earthquake by observing reactions and structural damage but the Richter scale does not do that.
The Mercalli scale measures the intensity of an earthquake by classifying it between one and twelve. One means instrumental which is the least intensity with twelve being catastrophic which is the worst. The instrumental is only detected by seismographs and catastrophic means total destruction of the areas affected by an earthquake. The Richter scale has similar numbers of measurements but meaning different things.
The Mercalli scale is not as reliable as the Richter scale, but allows geologists to study each earthquake and how future ones will affect specific areas.

Each scale is a valuable tool in measuring earthquakes, but I believe the Richter scale is the best method. The Richter scale is much more accurate, reliable, easier to understand and interpret, and has been proven to be beneficial over the years since it's been invented. The Mercalli scale, however, is helpful when attempting to find what areas were mostly affected by during an earthquake. In my opinion I think both scales should be utilized rather than just one.

References
Scales. (2006). The Richter And Mercalli Scales. The Geography Site. Retrieved March 21, 2007 from http://www.geography-site.co.uk
Stommel, R. (2007). Richter vs. Mercall: Not a Prize Fight. The Seattle Gov. Retrieved March 21, 2007 from http://www.seattle.gov
Ludwin, R. (2004). Earthquake Prediction. The Pacific Northwest Seismograph Network. Retrieved March 14, 2007 from http://www.ess.washington.edu
Noson, Qamar, & Thorsen. (1988). Washington State Earthquake Hazards: Washington State Department of Natural Resources, Washington Division of Geology, and Earth Resources Information Circular 85. U.S. Geological Survey. Retrieved March 14, 2007 from http://www.usgs.gov