2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
Scientists at the West Coast and
Alaska Tsunami Warning Center can track the speed of a tsunami as it moves across the Pacific Ocean, predicting the path of the wave and thus areas that are likely to be affected by it. This enables them to notify local officials of the impeding disaster and give warning to those who could be affected.
In this activity, you will be taking on the role of the warning center in calculating the approximate speed of three tsunamis and creating a time travel map that shows their arrival at specific locations.
Wave Speed Formula
Where speed (meters/second) = square root of g (acceleration due to gravity, which is
9.81meters/second depth in meters)
2 ) x d (water
To convert your units to meters/hour, multiply your initial answer by 3,600. Divide the result by 1,000 to convert from meters/hour to kilometers/hour. Round your final answer to the nearest whole number.
Travel Times Calculation
Your speed calculation initially will be in meters/second.
Convert meters/second to kilometers/hour using the following formulas:
1 hour = 60 minutes = 3,600 seconds
1 kilometer = 1,000 meters
Tsunami travel time
= Distance / Tsunami Speed.
Remember to convert the decimal part of the number to minutes by multiplying the decimal part by 60. For example, one point four (1.4) hours equals 1 hour and 24 minutes.

2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
Procedure:
1. Read each of the scenarios on your
“Tsunami Scenarios” handout.
2.
Label your West Coast USA map with each of the geographic locations presented in the scenarios. Mark earthquake epicenter (tsunami origin) locations in red marker and the land locations in blue marker.
3.
Choose your favorite scenario. Use your drawing compass to draw the wave front at each of this scenario’s locations as it radiates out from the epicenter. Place the compass tip on the epicenter and the pencil on the land location, then make the largest arc possible on the map in the ocean area.
Shade these wave fronts in accordance with how far the locations are from the epicenter, i.e. locations that will receive the tsunami first are red, shading though orange, yellow, green and finally blue for locations that will receive the tsunami last.
4.
Using the wave speed formula and the data in the scenarios, determine the approximate speed of the tsunami in each scenario. Write these below:
Scenario 1:
Scenario 2:
Scenario 3:
5.
Next, you need to work out the distance between the epicenter and land locations in each scenario.
By using the West Coast USA map handout, estimate the difference in latitude and longitude between the epicenter and the location (in degrees) and convert the value to km (1˚latitude
~ 110km, 1˚longitude ~ 70 km). They will then be able to use these values to calculate the distance with trigonometry.

2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
Anchorage, Alaska
(Epicenter)
Distance between the 2 locations
(C)
Latitude Difference (A)
= # degrees x 110 km
Portland, Oregon
Longitude
= # degrees x 70 km
+ B 2 = C 2 A 2 , so if you square root C 2 , it will give the distance, C.
E.g. Latitude difference between Anchorage and Portland
= 61°-45°=16°
= 6 x 110 km = 660 km
Longitude difference = 149°-122° = 27° = 27 x 70 km = 1890km
So, 660 2 + 1890 2 = C 2 , therefore C 2 = 4,007,700, so C ~2002 km
Remember the distance values you calculate here are approximates and straight-line distances (as the crow flies) between locations (a tsunami would propagate in a straight line across an ocean). Write down these distances below.
Scenario 1
Sand Point, AK to:
Kodiak, AK……………
Kauai Island, HI……………
Scenario 2:
Hilo, Hi, to:
San Diego, CA……………
Newport, OR……………
Monterey,
Scenario 3:
Cascadia SZ to:
Ocean Shores, WA……………
Seaside, OR……………
Crescent City, CA……………

2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
6.
Now work out the time it will take for the tsunami to reach each location in the scenarios using the distances you have just calculated and the travel time formula.
Record these below and mark on the map the order the tsunami in your chosen scenario will reach its locations (1 st , 2 nd , 3 rd ).
Scenario 1: to:
Kodiak, AK……………
Kauai Island, Hi…………… Newport, OR……………
Monterey, CA……………
San Diego, CA……………
Vancouver, Canada……………
Scenario 3:
Time to:
Ocean Shores, WA……………
Seaside, OR……………
Crescent City, OR……………
7. Which location(s) will have a local (near-field) tsunami?
…………………………………………………………………………………………………………
Which location(s) will have a distant (far-field) tsunami?
…………………………………………………………………………………………………………
8. List below some ways people at the locations might prepare and/or react to the approaching tsunamis in each scenario. Take into account any differences there may be with the amount of time they will have before the tsunami arrives.

2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
AK
CANADA
WA
OR
CA
HI
Sand
Seaside,
Kauai
Newport, OR
Island,
The WATWC
San Diego, CA
CA
Monterey,
Zone
Canada
Ocean Shores, WA

2008 SMILE Winter Teacher Workshop
Faster Than a Speeding Tsunami
You are a member of the tsunami hazard alert team at the West
Coast & Alaska Tsunami Warning Centre (WATWC) in Palmer,
Alaska and have been asked to analyze the following tsunami scenarios:
Scenario 1
Seismologists have just registered a large submarine earthquake near Sand Point, Alaska, that is big enough to produce a tsunami. The ocean depth is 4,000 m. Significant effects will be on the following cities:
•
Kodiak, Alaska
•
Kauai Island, Hawaii
•
Monterey, California
Scenario 2
Information has just come in via satellite that
DART buoys have detected a tsunami off Hilo,
Hawaii; with an ocean depth of 4,500 m. National authorities are trying to establish how much preparation time these cities will have:
•
•
San Diego, California
Newport, Oregon
•
Vancouver, Canada
Accounts of violent shaking, lasting around 30 seconds, have been reported across the coast of
Oregon. Initial details show the earthquake originated just off Astoria, Oregon in the Cascadia Subduction
Zone. Cities under immediate threat include:
•
•
Scenario 3
Ocean Shores, Washington
Seaside, Oregon
•
Crescent City, California