Creative+Assessment+(Week+10)

**Earthquakes and Richter Magnitude** media type="custom" key="12183480" align="center"


 * 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.

For instance;10^2= 100;10^1 =10; 101.7≈ 50.12 The exponents 1, 2, and 1.7 are the base-10 logarithms of 10, 100, and 50.12.

Seismologists use a **Richter Magnitude** scale to express the seismic energy released by an earthquake. The Richter Magnitude scale is a logarithmic scale representing the amplitudes of the seismograph reading. The chart below demonstrates Richter magnitude numbers and the explosive equivalent of energy that the magnitude represents.

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:

Questions: 1.According to the table what magnitude earthquake releases a similar amount of energy to small nuclear weapon? It is similar to a 4.0 Earthquake on the Richter Scale and 1,000 tons of TNT. 2. Approximately how many tons of energy was released during the August 23, 2011 earthquake off centered in Virginia? Approximately between 80,000 tons and 1 million tons of energy was released during August 23,2011 centered in Virginia. 3.Approximately how many tons of energy was released during the March 11, 2010 earthquake off of Japan? (8.9 on the Richter scale) A little less than 32 billion tons of energy was released during the March 11,2010 earthquake. 4.According to the chart, how many times greater is a 5.0 magnitude quake than a 4.0 magnitude quake? According to the chart, a 5.0 magnitude earthquake is 32 times the energy of a 4.0 magnitude earthquake.

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 magnitude quake? See any patterns? Does this pattern hold roughly true in the table? A 8.0 magnitude earthquake is 3.125 times greater than that of a 7.0 magnitude earthquake. A 9.0 earthquake is 32 times greater than the magnitude of an 8.0 magnitude earthquake. 6.

*Energy Released is in tons* 7.Approximately how many tons of energy was released during the 2010 earthquake in Haiti (7.1)? 680 killatons

8.Approximately how many tons of energy was released during the 2010 earthquake in Chile (8.8)? 240 megatons 9.Approximately how many tons of energy was released during the 1906 earthquake in San Francisco (7.9)? 10-15 megatons 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? Around a 9.5 magnitude earthquake. I initially utilized the graph above to figure out where the magnitude would be based around. From the table, I knew that it would be in between 9 and 10 so therefore said that it would be around a 9.5. Further research only elaborated on my point as I looked up online other charts online, and figured that it would be around a 9.5 magnitude quake.