Design a Seismograph Lab

Guiding Question:

Can you design and build a seismograph that can record the movements of simulated earthquakes?

Hypothesis:

We should be able to build a seismograph that works, but my hypothesis is that it’s going to be difficult to build one that works for every kind of earthquake, whether it’s tiny, moderate, or huge.

Materials:

- Chair

- Two wooden boards

- nails

- Two wires

- Two strings

- Weights

- Tape

- Book

- Paper

- Pencil case

- A pen

Procedure:

1. First, nail the two boards together to create a 90 degree angle.
2. Next, hang a string from the edge of the boards and attach a pen to it.
3. Add two weights to the pen so that it doesn’t dangle all over the place.
4. Put that whole contraption on top of a chair to keep the boards in place. To make it even more stable, rest it on top of the pencil case.
5. Put the strings and wires around the legs of the chair and attach them to the pen so that it is kept firmly in one spot.
6. Put a clean sheet of paper on a book under the pen so that the tip of the pen is just resting on the paper. The book represents any seismic activity, so in order to make a test, shake the book but move it in a certain direction at the same time. On the paper, there should be a long squiggly line, which is the seismogram.

Data Analysis:

Although I wasn’t there for the first part of the experiment, even while I was there, there were a lot of alterations that had to be made to the original design to make it work. Bigger earthquakes were supposed to cause bigger lines on the paper, but all that they seemed to do was make a bunch of random scribbles on the page. Eventually we realized that we were doing it wrong. Instead of shaking the book, we shook the chair, which was saying that the seismograph shakes, not the earthquake. Once our seismograph finally worked properly, we were able to easily see that if the earthquake is big, then the lines are really big and really close together. If there is no earthquake at all but the seismograph is still functioning, then it just draws a straight line.

Conclusion:

I liked this lab because it taught us about seismographs and about measuring earthquakes, and we were actually able to pretend there was an earthquake and measure it. I learned that the smaller lines on the seismograms meant the earthquake was really small, while bigger lines and bigger differences between them meant that the earthquake was very large. I also learned something about doing scientific labs in general, because we had to do so many tests. Even if you don’t figure out how to do the experiment right away, there’s always something that can be changed to make it function more properly. We tried many different ways of keeping the pen in one place at exactly the right level, but only the last one worked.

Further Inquiry:

If I were to do this lab again I would try to make a couple of changes to the design (seeing as I wasn’t the one to actually design it). First of all, I would try to create a long roll of paper kind of like toilet paper, so that you wouldn’t have to keep changing sheets of paper when there’s an earthquake and so that you can measure more than like 4 seconds of the earthquake. I think the wooden structure that we had was also kind of unnecessary, because by the time that we attached the strings and the wires to the chair and the pen at the same time, the wooden structure was doing basically nothing except keeping the chair in place. There are also probably a lot of other alternatives that are easier to keep the chair in place. If we have efficient seismographs then they would help the rest of the world by helping us understand the natural disasters around us and by helping us compare earthquakes all around the world so that it’s clear where most earthquakes occur, or where the faults of the world are.

A Tsunami Catastrophe

When people hear the word “earthquake”, they automatically think of big gaps in the earth, or small ridges forming, not huge waves in the ocean. However, a tsunami is another form of an earthquake. Tsunamis are a series of catastrophic ocean waves generated by seismic waves, or underwater earthquakes. The tsunami starts out as just a small wave around 3 feet tall, way out in the middle of the ocean. Still, the closer it gets to shore, the more energy the seismic wave reaps and the bigger the wave. By the end, there is an extreme tidal wave that usually ends up being around 50 – 100 feet tall. The worst tsunami ever recorded was 1640 feet tall, occurring in July of 1958 in Lituya Bay, Alaska. The effect they have on nearby cities is devastating, because even though people are usually given plenty of warning, the only things that can be saved are themselves.

There are a couple of different ways to predict tsunamis. Tsunamis are predicted similarly to normal earthquakes. One of the best ways to predict a tsunami is by making use of the seismograph network. This often causes false alarms, because not all ocean disturbances/earthquakes lead to tsunamis, but at least the people are prepared anyway, which is better than the alternative – being taken by surprise. The U.S. Tsunami Warning System was established in 1949 and was originally confined to the Pacific region, although now it has been expanded. They predict most tsunamis by using wave gauges and pressure monitors. Whenever they detect pressure building up in the Earth’s crust, then they know to warn the people who may be affected by the seismic waves. This still doesn’t guarantee a tsunami, but again, it’s better to be safe than sorry. Measurements of sudden sea level changes from satellites can also indicate a coming tsunami, which is another one of the ways to predict the huge waves.

Another interesting way of predicting tsunamis is forecast modeling. According to the National Oceanic and Atmospheric Administration, or NOAA, the helpfulness of forecast modeling stems from its ability to provide an estimate of wave arrival time and wave height. The way it works is that scientists have a database of pre-computed scenarios of tsunamis. When there is seismic activity in any area of the ocean, scientists receive that data from a satellite and compare it to other data they have, and by this they can try to figure out what the eventual tsunami will be like.

This is an example of what a satellite measurement looked like in Samoa:

As mentioned before, tsunamis are very devastating natural disasters. The prospect of just one wave destroying an entire city is hard to believe, sure, but the amount of energy in just one of a series of tsunamis is massive. When people know for sure that a tsunami is coming, they all panic. This is because they don’t really have a secure safe haven. It’s important for them to get up somewhere high, but if they can’t do that, what can they do? On January 17, 2005, in Sri Lanka, the Sri Lanka Public Security Ministry decided to put its coastal communities somewhere else, 200m from the sea so that they would be safer. The Prajnopaya Foundation created prototypes of a safe house that should be over five times more resistant than normal houses. The prototype is very special – there are four independent linear supports that cause the resistance against a tsunami to quadruple, there is bamboo ventilation which can be customized by the customer, and the walls are made of concrete. This is all very well for Sri Lanka, but it is necessary to have these types of things to protect all cities from incoming tsunamis. Scientists and others are still on the search for something easy that will completely protect most cities, but so far no luck. As well as their prediction system, the safe house system still has some flaws that need to be worked out.

If the predictions of the tsunamis don’t happen right away, or are late in being communicated to the population of a city, then there needs to be some sort of warning system, some sort of way to prevent too much loss of property and any possible loss of life. There are two main known types of warning systems – the Regional Warning System and the International Warning System. Both systems work together to inform the city that a tsunami is going to take place, by using the data from other countries and local seismic data. The tsunami warning systems are pretty much foolproof because they check with a bunch of different places around the world before setting the alarm, to make sure that it’s not a false alarm for something so urgent.

Well, yes – when a city is destroyed, people lose their homes. But a destroyed city can also cause a lot of other problems for the country. The government tends to be quite frantic about getting the natural disaster cleaned up, and in the mean time, it neglects other things that are important for its country, such as its political system, what’s going on in neighboring countries, etc. Society-wise, the population of the country tends to decrease a lot – there is nearly no tourism, and people that have lived there all their lives often decide differently for future years. As well as that, nobody wants to hang around after a huge catastrophe, so the country doesn't make as much money or profit and the economy crashes. For the people that do live there, food is a problem. If the food that they consume is local, then they are out of luck and the government is required to provide them food. All of the stores are crushed, any possible fish are either dead or gone very far away, so what are the people supposed to do? The effect that tsunamis have on a country’s appearance, society, culture, environment, and economy is terrible. This is why I hope that scientists do eventually find a good system that works well for all cases, and gives the country a chance to protect itself.

This is only a little bit of what a tsunami can do:

BIBLIOGRAPHY

NOAA. "Tsunami Modeling and Research." NOAA Center for Tsunami Research. Web. 22 Feb. 2011. .

Paulson, Tom. "Tsunami Detectives Hunt for Hidden Clues." Seattle News, Sports, Events, Entertainment | Seattlepi.com - Seattle Post-Intelligencer. Seattle Pi, 8 Jan. 2005. Web. 22 Feb. 2011. .

"Tsunamis." U.S. SAR Task Force Main Page. United States Search and Rescue Task Force. Web. 23 Feb. 2011. .

Achenbach, Joel, and Rob Stein. "Despite Advances, Science of Forecasting a Tsunami Is Inexact - Washingtonpost.com." Washington Post - Politics, National, World & D.C. Area News and Headlines - Washingtonpost.com. Washington Post, 28 Feb. 2010. Web. 24 Feb. 2011. .

"Tsunami Modeling and Research." NOAA Center for Tsunami Research. NOAA. Web. 24 Feb. 2011. .

Buoy, Dart. "Tsunami Forecasting." Library ThinkQuest. Library ThinkQuest. Web. 23 Feb. 2011. .

"Tsunami Safe(r) House." MIT SENSEable City Lab. Web. 24 Feb. 2011. .

Questions for Notes on Section 2-3 of the Textbook

Questions for Notes on Section 2-3 of Textbook
1a.What is a seismograph?
A seismograph is an instrument that is used to monitor, record, and examine and movements in the Earth’s crust. Seismographs and fault-monitoring devices provide data used to map faults and detect changes along faults. Geologists are also trying to use this data to develop a method of predicting earthquakes. The typical seismograph consists of some sort of base which absorbs the ground motion from the seismic waves of the earthquake. The top of it has a wire that hangs straight down and is attached to a pen with a weight that keeps the pen straight. Right on the tip of the pen is a rotating drum with a roll of paper that records the earthquake’s seismic waves which are produced by the seismograph. This is called a seismograph.
1b. How does a seismograph record waves?
A seismograph records waves with its rotating drum. The base absorbs the vibrations of the seismic waves, which then affect the whole seismograph. The pen is kept still by the weight it’s attached to, and the seismogram is recorded.
1c. A seismograph records a strong earthquake and a weak earthquake. How would the seismograms for the two earthquakes compare?
The seismogram for the stronger earthquake would have a bigger difference between the crests and troughs. The stronger earthquake also has more amplitude and more powerful waves recorded. The weaker seismic waves would cause a smaller disturbance and make much less stressed data.

2a. What four instruments are used to monitor faults?
The four instruments used to monitor faults are tilt meters, creep meters, laser-ranging devices, and GPS satellites. There is something different that each one measures, and they all have their own way of measuring the movement around them.

2b. What changes does each instrument measure?
Tilt meters measure the tilting or raising of the ground, or any vertical movement. The way the tilt meter works is with a water-level scale. Inside the scale is water, and whenever there is the slightest movement a little bit of water pours from one into the other. Creep meters measure the horizontal movement of the ground. With creep meters, there is a wire stretched across a fault and attached securely to one side. On the other side, there’s a weight. By using the measuring scale to tell how much the weight was moved, scientists can tell how much horizontal movement there was. Laser-Ranging devices are really simple – they use laser beams to detect horizontal fault movements. They consist of a laser beam, a laser reflector, and an observatory housing a laser. Lastly, GPS satellites are used very often. They orbit the earth to measure changes in elevation and tilt of the land as well as horizontal movement along a fault. Standing for the “global positioning system”, GPS satellites were developed to help ships and planes find their routes, and were more recently used for monitoring faults.

2c. A satellite that monitors a fault detects an increasing tilt in the land surface along a fault. What could this change in the land surface indicate?
An increasing tilt in the land surface along a fault is evidence that there might be an earthquake. This also refers to stress, because an increasing tilt in the land surface generally means that there is compression in that area. In many years, that fault may turn into a mountain range.


3a. What are three ways in which geologists use seismographic data?
The first and main way that geologists use seismographic data is to detect and attempt to predict earthquakes. This can be helpful for the entire world, and although there is no sure system of how to predict earthquakes geologists are getting there. Secondly, it’s also important for geologists to figure out how to map faults. This way, they know where most earthquakes will be, and seismographic data can help with that. A third way that geologists and scientists use seismographic data is to monitor the changes along faults that they have already discovered and mapped out. There is connection with this to predicting earthquakes, because by monitoring any changes in elevation, tilting of the land surface, or ground movements along faults, it’s much easier to discover whether there will most likely soon be an earthquake or not.

3b. How do geologists use seismographic data to make maps of faults?
When seismic waves encounter a fault, the waves are reflected off. Geologists use this data to map the fault’s length and depth. Faults are often hidden by a thick layer of rock and soil, so mapping hidden faults is very important.


3c. Why do geologists collect data on friction along the sides of faults?
Geologists collect data on friction along the sides of faults so that they can figure out which areas need to be watched for any disturbances that could possibly lead to an earthquake. With a high amount of friction the tension builds up in the fault, so it is much more likely to lead to an earthquake. With a very low amount of friction, everything is normal and no tension will be created.

Epicenter Lab

Hypothesis:
The epicenter for any earthquake is always going to be where all three circles meet, so my hypothesis is that the epicenter is somewhere near Tennessee.

1. Observe the three circles you have drawn. Where is the earthquakes epicenter?
The epicenter is in Tennessee, after all. All of the circles meet up there. By looking at the P and S waves and the difference between the two, I can tell that the last seismic wave located was in Denver, Colorado. The earthquake affected a lot of the United States, almost all of it except for parts in the west coast

Which city on the map is closest to the earthquakes epicenter? How far, in kilometers is this city from the epicenter?
The closest city is Nashville (Tennessee), which is 100 kilometers (approximately) away from the epicenter which is not very far at all.

3. In which of the three cities listed in the data table would seismographs detect the earthquake first? Last?
The P and S waves show that the first spot the seismographs would detect is Chicago, Illinois. That's because it's the closest to the epicenter of the earthquake, or at least compared to the other cities listed on the table. The second place detected would be Houston, Texas, and the last city the seismic waves would reach is Denver, Colorado.

4. About how far from San Francisco is the epicenter that you found? What would be the difference between P and S arrival times for a recording station in San Francisco?
It's about 3,200 km away from the epicenter, which I found out by using a compass. The difference between the P and S arrival times for a recording station would be around 4 minutes and 40 seconds.

5. What happens to the difference between the P and S waves arrival times as the distance from the earthquake increases?
The distance between the arrival timing of the P and the S waves grows as the distance from the earthquake increases. For example - San Francisco is farthest away from the epicenter and would have the biggest difference between the arrivals of the two waves.

6. Review the procedure you followed in this lab and then answer the following question. When you are trying to locate an epicenter, why is it necessary to know the distance from the epicenter for at least three recording stations?
It's necessary to know the distance from the epicenter because otherwise you can't figure out the difference between the arrival timing of the P and S waves. As well as that, you need all three circles to find more or less the exact point of the epicenter - one circle just isn't specific/reliable enough.