# Geology Lab

m7md98_
GEOL110L_Lab5_Tsunamis1.pdf

Tsunamis

LABORATORY 5

Name: Section: Date:

1. Watch this short Ted-Ed video on how tsunamis work to answer the questions below: https://www.youtube.com/watch?v=Wx9vPv-T51I

a. How do tsunami waves differ from normal waves?

b. List three different ways tsunamis can form.

c. Although tsunamis differ from your average ocean wave in several ways, their ba- sic “anatomy” is the same. Draw and label the characteristics of an idealized ocean wave. Include: crest, trough, wave height, and wavelength. Use an arrow to indicate the direction of wave movement.

NATURAL DISASTERS: LAB 5

Exercise 2. Can you outrun the tsunami? Borrowed from NOAA.

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Introduction Knowing information about wave physics can save lives. You may have seen videos of the terrible destructive power of tsunamis. These shallow-water waves happen when large amounts of water are displaced. When scientists detect these disturbances, they can figure out how fast the tsunami is traveling, where it will hit and when. In this way, they can do their best to evacuate people nefore the tsunami hits and save lives. Today, that is your job!

In this exercise, you will play the role of a scientist working for NOAA that has received infor- mation about a disturbance in the ocean. Unfortunately, the high-tech computing systems have shut down. How are you going to figure out where and when the tsunami will strike?

Procedure For this activity, you will be given a scenario of the location of disturbance (i.e., the origin or epicenter of the tsunami) you detected and the depth at which it occurred. You will use this information to calculate the speed of the tsunami and when it will affect given locations.

1. Read the Tsunami Scenario and identify the location on a map.

2. Use the wave speed formula below to calculate the speed at which the tsunami is traveling.

3. Fill out the information sheet that will be passed on to emergency services personnel to help warn and aid people in the affected areas.

1 km = 1,000 m 1 hr = 60 min 1 min = 60 sec

speed = √(g x d)

Wave Speed Formula The speed of a tsunami is equal to the square root of g (the acceleration due to gravity, which is a constant value of 9.81 m/s2) times the water depth (d) at which the disturbance occurred (meters).

NATURAL DISASTERS: LAB 5

Exercise 2. Can you outrun the tsunami? Borrowed from NOAA.

PAGE 3NATURAL DISASTERS

Calculating Time to Affected Locations To figure out how long it will take for the tsunami to reach the affected locations, first calcu- late the distance in meters between the epicenter and the affected location. Use Google to find the coordinates (latitude and longitude) of the epicenter and each location. Enter the information for the epicenter and location at the website below to find the distance between them in km and multiply by 1,000 convert to meters.

http://www.chemical-ecology.net/java/lat-long.htm

Once you know the distance, multiply by the speed of the tsunami to find out how long you have before the tsunami strikes.

Distance (meters)/Speed (m/second) = time until tsunami (seconds) State your final answer in hours, minutes and seconds.

Tsunami Scenario You received information that there was an earthquake in Seward, Alaska large enough to produce a tsunami at an ocean depth of 4,000m. Calculate the speed of the tsunami at this depth. Then, calculate the time it will take the tsunami to reach the two following affected locations:

a. What is the speed of the tsunami? Please show your work.

b. How long will it take to reach each location?

NATURAL DISASTERS: LAB 5

Exercise 2. Can you outrun the tsunami? Borrowed from NOAA.

PAGE 4NATURAL DISASTERS

c. List the locations in order in which the tsunami will strike in the table below. Indicate some actions at each location that should be taken to help local citizens.

ORDER OF STRIKE

AFFECTED LOCATION (INCLUDE COORDI-

NATES)

TIME UNTIL TSUNAMI

HITS

EMERGENCY ACTIONS

1st

2nd

Exercise 3. The Sumatra-Andaman Earthquake and Tsunami.

a. On the map (Figure 1) below, highlight the epicenter of the earthquake and Sri Lanka.

b. Name the four tectonic plates associated with the main shock and ensuing aftershocks:

NATURAL DISASTERS: LAB 5

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Exercise 3. Figure 1.

c. Draw and label the tectonic boundary between the Indian-Australian and Burma Plates. La- bel the Sunda Trench on your drawing. What type of boundary did you just draw?

NATURAL DISASTERS: LAB 5

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Exercise 3. The Sumatra-Andaman Earthquake and Tsunami.

d. List at least three geologic features shown on Figure 1 that confirms the tectonic plate type you drew above.

e. There were other factors at play which heightened the death toll of this horrible event. Please read the following BBC article and highlight the main points: https://www.bbc. com/news/world-asia-45663054

f. Lastly, please use the following link and scroll down to the section on the U.S. West Coast to answer the question... Could it happen here? https://www.usgs.gov/centers/pcmsc/science/could-it-happen-here?qt-science_cen- ter_objects=0#qt-science_center_objects

4. Explore another historical tsunami event of your choosing to fill out the table below.

YEAR OF EVENT COUNTRY OF OCCURRENCE

OCEAN BASIN OF OCCURRENCE

MAGNITUDE OF EARTHQUAKE/ OTHER CAUSES

DEATH TOLL