Tracking Down the Source

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Dina Jordan
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1 Tracking Down the Source Overview: In this lesson, students use online databases and Google Earth to track down the source of a tsunami. (NOTE: Please teach the GIT Lesson on placemarks prior to this lesson.) Targeted Alaska Grade Level Expectations: Science [] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [8] SD2.1 The student demonstrates an understanding of the forces that shape Earth by interpreting topographical maps to identify features (i.e., rivers, lakes, mountains, valleys, island, and tundra). [6] SD2.3 The student demonstrates an understanding of the forces that shape Earth by describing how the surface can change rapidly as a result of geological activities (i.e., earthquakes, tsunamis, volcanoes, floods, landslides, avalanches). Objectives: The student will: use databases to research earthquakes and volcanoes in Alaska for a particular year; plot locations of possible tsunami sources on Google Earth; evaluate locations to predict the source; and compare the prediction to the actual source listed in a database. Materials: Computer with Internet access Google Earth STUDENT WORKSHEET: Tracking Down the Source STUDENT WORKSHEET: And the Source is Science Basics: Earthquakes, landslides and volcanoes are significant tsunami triggers. In the Pacific Ocean, earthquakes have been the cause of 83% of tsunamis. Landslides are the second most common cause. The 1964 Alaska Earthquake probably caused around 20 local slide-generated tsunamis within minutes after the shaking began. Volcanic activity has been the source of 92 major tsunamis. Volcanic activity that is known to produce tsunamis include earthquakes accompanying eruptions, pyroclastic flows encountering water, submarine explosions, calderas collapsing or volcanic landslides. Activity Procedure: 1. Explain students will use Google Earth to help them track down the source of a mysterious tsunami wave. ATEP 2008 UAF Geophysical Institute B-38 Unit 3: Tracking Down the Source

2 2. Distribute STUDENT WORKSHEET: Tracking Down the Source. Review the information on the first page of the worksheet then allow paired students to complete the worksheet. 3. When students are finished discuss students predictions. 4. Distribute STUDENT WORKSHEET: And the Source is for student completion. 5. Discuss student responses to questions on the worksheet. Answers: STUDENT WORKSHEET: Tracking Down the Source 1. A placemark should designate Main Creek in Amber Bay on Google Earth. 2. A placemark should designate Karluk, Alaska on Google Earth. 3. Month/Day Latitude Longitude Magnitude (MS) 03/ N W / N W / N W / N W Placemarks should be placed on the four 1938 earthquakes in Google Earth. 5. Cleveland, Makushin and Okmok 6. Placemarks should be placed on the three above-mentioned volcanoes in Google Earth. 7. Answers will vary. STUDENT WORKSHEET: And the Source is 1. Earthquake Month/Day 11/10 Magnitude Tsunami Source Location Latitude Longitude Maximum Water Height Shumagin Islands, AK.30 m 2. The student s response should be a brief summary of the following information from the Historical Tsunami Database at the National Geophysical Data Center: A magnitude 8.3 submarine earthquake, centered in a sparsely populated area near the Alaska Peninsula, generated a surprisingly small tsunami. It is conjectured that the tsunami was the result of submarine landslides or more likely to a very minor surface deformation associated with the earthquake. 3. Answers will vary. 4. Yes, tsunamis that have traveled across the Pacific from locations outside of Alaska will not be listed as a source in the databases for earthquakes or volcanoes in Alaska. 8.3 ATEP 2008 UAF Geophysical Institute B-39 Unit 3: Tracking Down the Source

Tracking Down the Source (page 1 of 2) In 1938, a trapper, John Hillborn, and his boat survived a tsunami at Main Creek, which flows into Amber Bay on the Alaska Peninsula.

3 Tracking Down the Source (page 1 of 2) In 1938, a trapper, John Hillborn, and his boat survived a tsunami at Main Creek, which flows into Amber Bay on the Alaska Peninsula. This tsunami was also witnessed in the village of Karluk on Kodiak Island. Where did this tsunami come from? What was the source? With a partner, complete the process below to eliminate possible sources and reveal the source of this mystery wave. 1. On the map below, locate the mouth of Main Creek. Use this map to find the mouth of Main Creek on Google Earth; add a placemark to designate this location. Map courtesy Alaska Geospatial Data Clearing House and USGS 2. Enter a Google Earth search for Karluk, Alaska. Add a placemark to designate the village of Karluk. ATEP 2008 UAF Geophysical Institute B-40 Unit 3: Tracking Down the Source

4 Tracking Down the Source (page 2 of 2) Earthquakes and Landslides Earthquakes, landslides and volcanoes are significant tsunami triggers. In the Pacific Ocean, earthquakes have been the cause of 83% of tsunamis. Landslides are the second most common cause. The 1964 Alaska Earthquake probably caused around 20 local slide-generated tsunamis within minutes after the shaking began. 3. Go to Earthquake Database Search at the Alaska Earthquake Information Center at alaska.edu/html_docs/db2catalog.html. Enter search dates from the beginning of 1938 to the end of Then click Submit. Record results in the table below. Month/Day Latitude Longitude Magnitude (MS) 4. In Google Earth, place a placemark on the location of each earthquake. Volcanoes Volcanic activity has been the source of 92 major tsunamis. Volcanic activity that is known to produce tsunamis includes earthquakes accompanying eruptions, pyroclastic flows encountering water, submarine explosions, calderas collapsing or volcanic landslides. 5. Go to the Alaska Volcano Observatory website at Click on Volcano Information then Eruption Search. Search for eruptions in In the table below, write the names of the three volcanoes listed and read the description of each eruption from that year. Record any notes you feel are important in the second column. Volcano Notes on eruption 6. In Google Earth, use the Geographic Features layer to help identify the location of the volcanoes. Place a placemark on each volcano. Analysis Consider your notes from each eruption, the location of each earthquake, and examine the map with the placemarks to apply what you have learned about wave propagation. 7. Which event triggered the tsunami? Why? ATEP 2008 UAF Geophysical Institute B-41 Unit 3: Tracking Down the Source

5 And the Source is... Access the NOAA/WDC Historical Tsunami Database at National Geophysical Data Center (NGDC) at the following URL: On the left-hand side, click on Alaska. 1. Complete the following table for the 1938 tsunami. Month/Day: Tsunami Source Location: Longitude: Latitude: Maximum Water Height: Magnitude: 2. Briefly summarize the description of comments on the tsunami. 3. Does this confirm your original prediction after analyzing the events on the previous worksheet? Further Question: 4. Would it be possible that a source for a tsunami in Alaska may not be listed in the Earthquake Database Search at the Alaska Earthquake Information Center, or in the eruption search at the Alaska Volcano Observatory? Why, or why not? ATEP 2008 UAF Geophysical Institute B-42 Unit 3: Tracking Down the Source

Contour Line Overlays in Google Earth

Contour Line Overlays in Google Earth Overview: Students download a section of a topographic map of their community from the ATEP website. This file will overlay the Google Earth satellite imagery. Students use the path tool to trace a contour