WebQuest

Earthquake

Process

"There's a 100% Chance of an Earthquake Today"

The United States Geological Survey claims: "There is a 100% chance of an earthquake today". Your job will be to research and interpret statistical facts on earthquakes.

PowerPoint Slide 1: Using your knowledge of probability and statistical evidence, you will agree or disagree with the statement "There is a 100% chance of an earthquake today". Use 3-5 statistics from the sites below to support your statement. Some things to consider in your response are the importance of location, magnitude, history of earthquakes, destruction, and how these statistics relate to probability.

PowerPoint Slide 2: Create 2 earthquake probability maps from Earthquake Probability Maps. for your zip code. Map 1 will be of magnitude 5.0. Map 2 will be of magnitude 7.0 or greater. Answer the question: Do these maps support my statement in Slide 1? Support your statement with 3-5 reasons from your interpretation of the maps.

Physics of Earthquakes

Earthquakes result in massive movement of the ground. Anyone who has experienced a serious earthquake can attest to the violent shaking it produces. In this section, the focus will be on earthquakes as an application of our study of the physics of vibration and waves.

The cause of an earthquake is a release of energy deep within the Earth at a point called the focus, or hypocenter, of the earthquake. The point on the Earth's surface radially above the focus is called the epicenter. As the energy from the focus reaches the surface, it spreads out along the surface of the Earth. We might expect that the risk of damage in an earthquake decreases as one moves farther from the epicenter, and over long distances, that assumption would be correct. Of course, structures in Kansas are not affected by earthquakes in California. In regions close to the earthquake, however, the notion of decrease in risk with distance is not consistent and misleading.

In order to assess the risk of damage to structures in an earthquake, two factors must be considered: soils and resonance. You can learn about the effects of these two factors by visiting the following websites:

Factors that affect damage in an earthquake

1. Soils and Earthquakes.

a) What is Liquefaction? – And how does it affect building structures?
b) Liquefaction video – Liquefaction in action!
c) Liquefaction Prevention – Minimizing the potential disaster
d) Rate of Energy Transfer for a Wave – How are amplitude of vibration and the wave propagation speed of an earthquake related? Download and read this Word/PDF document to find out!
e) Earthquake Simulator -- Time to RUMBLE!!! Make your own earthquake!

2. Resonance – Standing Waves, and Resonant Frequency

Exactly how do structures and the earth itself vibrate? Why is this often so destructive in the case of the earthquake? Or, alternatively, why does your big home theatre sound system make the books fall off the shelves?

a) Beginning with the basics, follow these links to discover the important phenomenon of resonance:

ABCs of Resonance

What is resonance?

Understanding Resonance

b. Some common examples of resonance:

Playground Swing Resonance (Tesla's favorite example)

Standing waves on a string

Resonance on a string - interactive (turn amplitude slider all the way up)

Glass Breaking (including cool video)

c. How exactly does resonance factor into earthquakes?

Earthquake Resonance

Build your own Building-Earthquake demo

Demonstrate shaking structures (turn off pop-up blockers)

Using the information gathered from above, you are now ready to examine the following four cases:

Case Study 1: Northridge, California, January 17, 1994 (Read the 2nd paragraph very carefully.)

"Although the city of Santa Monica sits 25 kilometers from the shock's epicenter, it suffered more damage than did other areas less than one-third that distance from the jolt." [1]

What caused the earthquake to be more intense at the epicenter than at the focus? On what type of soil was the city built on?

Case Study 2: Kobe, Japan, January 17, 1995

The earthquake itself was only moderate in magnitude. And despite the fact that many of the buildings were well-equipped to easily withstand moderate earthquakes by the use of shock absorbers and dampeners, the earthquake has resulted in an extensive damage throughout the city because many of the structures have toppled over. Which of the factors characterizes this type of earthquake damage in Kobe, Japan?

Case Study 3: Collapse of Nimitz Freeway during Loma Prieta earthquake on October 17, 1989

The portion of the freeway that collapsed was built on mudfill, but the surviving portion was built on bedrock. Suppose the seismic wave moves from granite (bedrock) into mudfill with similar density but with a much lower wave speed of propagation. When the wave crosses over from granite to mudfill, let's assume the speed of the wave drops by a factor of 25 with negligible reflection of the wave. Will the amplitude of the ground shaking increase or decrease? By what factor? This phenomenon led to the collapse of part of the Nimitz Freeway in Oakland, California, during the Loma Prieta earthquake of 1989.

Case Study 4: Michoacan earthquake, September 19, 1985

"An earthquake rattled the coast of Mexico in the state of Michoacan, about 400 kilometers inland, the ground shook even less, and by the time the waves were 100 kilometers from Mexico City, the shaking had nearly subsided. Nevertheless, the seismic waves induced severe shaking in the city, and some areas continued to shake for several minutes AFTER the seismic waves had passed. Some 300 buildings collapsed and more than 20,000 people died." - American Scientist, November-December 1992, p. 566.

What was the primary cause of extensive damage in Michoacan earthquake? (Reread the emphasized part of the quote very carefully.)

Math – Logarithms and How Earthquakes are measured

Earthquakes can be measured using the Richter Scale. Most earthquakes are between 0.0 and 6.0 on the scale, but some extremely devastating quakes weigh in at 7.0 or even higher. The Richter Scale is based on a logarithmic function where the amount of seismic energy released is the variable. The reason that an earthquake measuring 6.0 and an earthquake measuring 7.0 on the Richter Scale are so different is because the numbers come from a logarithmic function. In this section of your project, you will be working with the Richter Scale and logarithms. By the end of this section you should know why a 6.0 earthquake and a 7.0 earthquake are extremely different.

Remember what a logarithm is? If not read about them here (read this even if you remember because it's helpful for a couple of the questions):

Here is a very helpful tutorial that shows you where a couple of the properties of logarithms come from:
http://youtube.com/watch?v=yEAxG_D1HDw

Click on the "click here to start" button to have fun with a logarithm graph. (Maybe these can be images to go on your slide?) Also, click on the links at the bottom to help with your questions:
http://www.analyzemath.com/logfunction/logfunction.html

One more interesting link that discusses logarithms. This link also has applications of the logarithmic function (including sound measurement). Make sure to go to all the pages:
http://physics.mtsu.edu/~wmr/log_1.htm

You should know what the Richter Scale is and what the numbers mean.
What is the Richter Scale?

More information about the Richter Scale.

Questions for your PowerPoint:
1. Answer part A or part B:

A) Is an earthquake of magnitude 4 twice as powerful as an earthquake of magnitude 2? Explain why or why not.
B) If our original earthquake measures 6.0 on the Richter Scale, what would be the Richter Scale measurement of an earthquake which has 1/5 the energy or the original? Show where your answer came from.

2. Answer part A or part B:

A) Explain why log(b^x)=x(log(b)).
B) Explain why log(mn)=log(m)+log(n). OR Explain why log(m/n)=log(m)-log(n).

Biology – The Public Health Impact of Earthquake

An important part of studying biology is understanding health. What factors influence human health and how they do so is a big part of the field of Public Health, a sub-discipline of Biology. Public Health is the science of protecting and improving the health of communities through education, promotion of healthy lifestyles, and research for disease and injury prevention.

Natural distasters, such as earthquakes, cause many problems that affect the health of humans and populations throughout the world. Factors such as disrupted and contaminated water systems, dust and debris from collapsing buildings, untreated injuries, and emotional stress from surviving trauma can significantly influence the health of people in communities affected by earthquakes.

The following questions will help you to research and figure out ways in which these public health problems can be understood and appropriately addressed. Pick two out of the three questions. Answer the questions using the websites listed, and create 2-4 powerpoint slides presenting your answers to the questions you picked. Be creative!

1. If a powerful earthquake disrupts water systems, the water that people usually use may become exposed or contaminated. As you have learned in biology class, many diseases are caused by tiny (microscopic!) bacteria and viruses that can exist in polluted, or contaminated, water or air.

Pick one waterborne disease and complete the following parts (a-c) by using the websites listed below:

http://www.cdc.gov/Ncidod/dpd/healthywater/index.htm

http://www.who.int/water_sanitation_health/diseases/diseasefact/en/index.html

http://www.cellsalive.com/parasit.htm

http://www.amnh.org/nationalcenter/infection/index.html

a) The bacteria or virus that causes the disease in humans

b) The main important biological factors of the bacteria or virus

c) How the bacteria or virus affects humans, or in other words, what are the signs and symptoms of the disease that the bacteria or virus causes?

2. The way that doctors often treat bacterial diseases is by prescribing antibiotics, medicines that help to kill the bacteria inside the human body.

http://www.youtube.com/watch?v=X9aLFgqgd6A

http://www.britannica.com/eb/article-9059068/penicillin

http://www.brainpop.com/health/diseasesandconditions/antibioticresistance/

a) Name a disease that is often treated with antibiotics.

b) What was the first antibiotic ever used, and how was it discovered?

c) Explain the current problem of antibiotic resistance. Use a simple

outline describing the main points.

3. What can happen to someone if they don't have access to clean drinking water for a long period of time, because of the damage done by the earthquake?

http://www.kidshealth.org/teen/safety/first_aid/dehydration.html

http://ga.water.usgs.gov/edu/drinkseawater.html

http://www.scienceiq.com/ShowFact.cfm?ID=155

http://www.nlm.nih.gov/medlineplus/ency/article/000982.htm

a) What are the signs and symptoms of this problem?

b) Why can't we drink salt water?

c) What would you have to do to seawater to make it drinkable?