Earthqyakes

http://www.theatlantic.com/infocus/2011/03/earthquake-in-japan/100022/



http://earthquake.usgs.gov/earthquakes/states/events/1964_03_28.php



http://earthquake.usgs.gov/earthquakes/states/events/1906_04_18.php


 * Ryan Sullivan and Arthur Xu**

__**Earthquakes and Richter Magnitude**__

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On Tuesday, August 23, 2011, two sizable earthquakes occurred in the US. One was in Colorado with a magnitude of 5.3 and the other was centered in Virginia with a magnitude of 5.8 … which we felt here in Massachusetts. Seismologists view images on seismographs like this image on the right from Tuesday’s earthquake. They calculate the vertical distance between the extremes on this image and call that the amplitude of the shake. The Richter Magnitude of the earthquake is the base-10 logarithm of that amplitude. Logarithms are related to exponents. Base-10 logarithms are the exponent required to bring 10 to a certain number.

Let's take a look at the seismic wave energy yielded by our two recent U.S. examples of recent activity and compare those to earthquakes and other phenomena. For this we'll use a larger unit of energy, the seismic energy yield of quantities of the explosive TNT:


 * Richter TNT for Seismic Example**


 * Magnitude Energy Yield (approximate)**


 * -1.5**- 6 ounces Breaking a rock on a lab table


 * 1.0**- 30 pounds Large Blast at a Construction Site


 * 1.5**- 320 pounds


 * 2.0**- 1 ton Large Quarry or Mine Blast


 * 2.5**- 4.6 tons


 * 3.0**- 29 tons


 * 3.5**- 73 tons


 * 4.0-** 1,000 tons Small Nuclear Weapon


 * 4.5**- 5,100 tons Average Tornado (total energy)


 * 5.0**- 32,000 tons


 * 5.5**- 80,000 tons Little Skull Mtn., NV Quake, 1992


 * 6.0**- 1 million tons Double Spring Flat, NV Quake, 1994


 * 6.5**- 5 million tons Northridge, CA Quake, 1994


 * 7.0**- 32 million tons Hyogo-Ken Nanbu, Japan Quake, 1995; Largest thermonuclear weapon


 * 7.5**- 160 million tons Landers, CA Quake, 1992


 * 8.0**- 1 billion tons San Francisco, CA Quake, 1906


 * 8.5**- 5 billion tons Anchorage, AK Quake, 1964


 * 9.0**- 32 billion tons Chilean Quake, 1960


 * 10.0**- 1 trillion tons (San-Andreas type fault circling Earth)


 * 12.0**- 160 trillion tons (Fault Earth in half through center,

OR Earth's daily receipt of solar energy)

Questions:

1. According to the table what magnitude earthquake releases a similar amount of energy to small

nuclear weapon? - **A magnitude of 4.0 would release the same amount of energy as a small nuclear bomb according to the table.** 2. Approximately how many tons of energy was released during the August 23, 2011 earthquake off

centered in Virginia? - **It would have released around 90,000 tons of energy because it is between 5.5 and 6.0 on the scale.** 3. Approximately how many tons of energy was released during the March 11, 2010 earthquake off of

Japan? (8.9 on the Richter scale) - **Since 8.9 is nearly 9.0 on the scale the quake would have released around 32 billion tons of energy.** 4. According to the chart, how many times greater is a 5.0 magnitude quake than a 4.0 magnitude

quake? - **It is about 32 times larger. The two values are 1,000 tons and 32,000 tons. If you multiply 1,000 by 32 you get 32,000.** 5. According to the chart, how many times greater is an 8.0 magnitude quake than a 7.0 magnitude

quake? How many times greater is a 9.0 magnitude quake than an 8.0 ma - **It is 31.25 times larger between 7.0 and 8.0 and 32 times larger between 8.0 and 9.0. This pattern repeats towards the end of the table.** 6. Using the information from the table create a graph that gives the energy yield for any Richter

magnitude. Put Richter magnitude on the x-axis and put energy yield on the y-axis. 7. Approximately how many tons of energy was released during the 2010 earthquake in Haiti (7.1)? - **About 47 million tons according to the table.** 8. Approximately how many tons of energy was released during the 2010 earthquake in Chile (8.8)? - **According to the chart it would produce around 25 billion tons** 9. Approximately how many tons of energy was released during the 1906 earthquake in San Francisco
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(7.9)? - **Around 1 billion tons according to the chart.** 10. Using either your graph or the table write an exponential equation that gives the energy yield for any

Richter magnitude. **- M = 2/3log(E/Eo) M= Magnitude E= the seismic energy released Eo= the energy released by reference quake. ** 11. An earthquake has a seismic energy release of approximately 500 billion tons. About what magnitude

earthquake was this?
 * - Approximately a 9.5 magnitude earthquake.**