Unit 2.1 Extension: Wave Application to Hunga Tsunami Wave Data
Summary
Waves are observable all over the place, so why do they exist? Students conduct experiments to examine wave speed, then use data to analyze wave speed, distance traveled, and time elapsed for the tsunami wave created by the Hunga Tonga volcanic eruption that occurred on January 14, 2022. In these follow-up extension activities to Unit 2.1, students are asked to complete the same analysis that they completed in the Unit 2.1 Slinky Lab, but this time with data from a real-world event.
Collapse
Learning Objectives
After completing this unit, students will:
- Use mathematical representations to support a claim regarding relationships among the time elapsed/period, distance traveled/wavelength, and speed of a traveling wave pulse.
- Develop the concepts of direct and inverse proportionality in order to determine the properties of the wave that have direct and inverse relationships.
- Gain confidence in interpreting and plotting data in order to apply data analysis and interpretation skills independently and without prompting or explicit instructions.
Context for Use
This Unit is labeled as a pair of extension lab activities because the quantitative skills analyzed are the same as in Unit 2.1. However, this unit is also fine as a standalone unit.
This material is suitable for any undergraduate level and requires that the students have some introductory experience with unit conversions.
Plan for these activities to each take about 60 min of class time to complete, plus an additional 60 minutes if the Water Waves Extension Lab is completed. The first activity (experiment) is designed for smaller classroom/labs, whereas the second activity is easily adaptable to large and small classrooms. While the data activity materials are written assuming an in-person synchronous classroom, they could be adapted to an asynchronous classroom without much effort.
Description and Teaching Materials
Teaching Materials:
All Slides: Unit 2.5 All Slides v2 (PowerPoint 2007 (.pptx) 38.4MB Aug30 24)
Water Waves Experiment:
- Materials: Stream trays (and tape to plug hole) (trays like this are available from several educational materials distributors), pitchers and buckets (for filling, accidental leaks, and emptying), yard sticks, rulers, stopwatch/timer, rock (or other obstacle) for observing wave refraction
- Water Waves Instructions -
- Water Waves Worksheet U2.1E Water Waves Lab Worksheet.docx (Microsoft Word 2007 (.docx) 347kB Feb1 24)
Unit 2.1E Water Waves Lab Instructions -- educator-only file
HideTsunami Wave Speeds Lab:
- Pre-Class Assignment -
- Hunga Tonga Tsunami Wave Data Lab Handout U2.1E Hunga Tonga Tsunami Wave Data Lab Handout.docx (Microsoft Word 2007 (.docx) 277kB Feb1 24)
- Hunga Tonga Tsunami Wave Data Lab Handout -
- Data from Hunga Tonga Eruption - This is the master file with calculations of all the wave speeds to compare with student data
- Wave Height Individual Station Data from Hunga Tonga Eruption - It is not required that instructors use this file. This is a download of many individual station data files throughout the Pacific Ocean basin on the date of the eruption. The wave height data are unfiltered and can give you an idea of what the full datasets look like. Each station is given an individual tab with embedded links for how to access the data yourself.
Scientist Spotlight Full Resource (In this unit: Jazmin Scarlett): Scientist Spotlight Slides (PowerPoint 2007 (.pptx) 4.6MB Jul8 24)
Reflection: U2.1E Reflection.docx (Microsoft Word 2007 (.docx) 69kB Jun24 24)
Pre-class Assignment(s):
- Answer a short warm-up question: What data do you need to calculate a wave speed, and how do you calculate it?
- Complete Scientist Spotlight: Read about Jazmin Scarlett and be prepared to share something interesting or surprising about her.
In Class Part 1: Water Waves Experiment (60 min)
Introduction (5 min)
- Today we will make direct observations and measurements of waves and wave motion in water. Encourage students to use their prior experience to make hypotheses today and not to worry about their hypotheses being "right." Suggest to them that today, the entire objective of the experiment is to learn either by confirming or refuting their hypotheses.
- Instruct students that they will make and test hypotheses about wave speed motion in the "open water" (within the confines of our trays).
- If time permits, we will also observe wave refraction.
Hypothesis and Experimentation (45 min)
- Carefully tape up the drain hole in the tray to keep the water contained.
- In lab groups, students begin by writing a hypothesis (prediction) that relates the depth of water to the speed the waves will travel (e.g. waves will travel faster/slower in deeper/shallower water).
- In their groups, students will set up experiments that allow them to compare conditions for their hypotheses and record their data as evidence to support or refute their hypothesis. A good approach for this is to determine at least 3 depths they will fill their trays to and collect wave speed data for each depth.
- Before collecting data, there are two important steps that students should complete:
- First they must experiment with a simple, repeatable, reliable way to generate a wave in the tray. A fail-safe recommendation is to lift one end of the tray some small measured distance (e.g. 1cm) and firmly set the tray down to propagate a wave. But, they can (and should) experiment before being provided with this fail-safe approach!
- Second, they should measure the distance along the tray, and do a pre-experiment timing test to see if they can reliably time a wave propagating along the length once. If that speed is too fast, they may need to time the wave traveling the length of the tray and returning to the starting point. If they do this, they will need to either halve their measured time or double their measured tray length to record their wave speed trials.
- For data collection, students will need to complete multiple trials at multiple depths in order to get enough data to confidently confirm or refute their hypothesis.
- Once the data has been collected, students should make a graph of their average wave speeds at different water depths. Using their graph, they should evaluate their hypothesis and try to explain (or ask questions about) the relationship between water depth and wave speed.
- If time permits, students should use their stream trays to observe wave refraction before cleaning up. This is a good place to use video recordings to help make observations. Students should add at least one obstacle (e.g. a rock) to the tray, then propagate a wave and observe the wave behavior around the obstacle. Using their video or direct observations, students should make annotated sketches of their observations and use their observations to hypothesize about how wave refraction might contribute to erosion.
Discussion & Wrap Up (10 min)
- Wrap up the lab with a whole class discussion. Ask students to share out their findings both regarding their hypotheses and wave refraction. This is a great place to discuss "failure" (and embrace it) in the process of science and hypotheses. Regardless of the "right or wrong" initial hypotheses for the experiment, everyone gained the same knowledge about wave speeds as they related to water depth. This lab and findings about the relationship between wave speed and water depth lead in perfectly to the tsunami data activity that follows.
In Class Part 2: Tsunami Data (60 min)
Introduction (5 min)
- Scientist Spotlight on Jazmin Scarlett. Discussion Questions:
- What did you find interesting and/or surprising about this scientist?
- Are there any aspects of Scarlett with which you identify?
Hypothesis and Experimentation (45 min)
- (~45 min) Complete the Unit 2.1 Extension Activity: Hunga Tonga Tsunami Wave Data Analysis. In this activity, students access tsunami data from the NCEI Tsunami Data web page and use individual station data to calculate the speed of the tsunami wave generated by the Hunga Tonga eruption. This activity parallels the Unit 2.1 Slinky Lab but for a very different dataset.
- Make this more relevant to your students: convert km/hr to mph so that students can understand just how fast this wave propagates in units that they are more familiar with.
- Add an interactive component: each student is only tasked with calculating the wave speed for three stations, but they add their results to a class map of the Pacific Ocean basin. If your classroom has a large map, then you can bring post-it notes and students can add their data to the map. Otherwise, set up an editable google slides document: students can use insert→Shape to add a square, then double-click on the square to add text. See instructor stash for sample classroom data.
- Develop map reading and location skills: students find the location of a site from latitude/longitude coordinates to place on a map.
- Gain quantitative confidence: Students are repeating the same analysis in the Unit 2.1 Slinky Lab compared to this lab. Completing the same analysis with a different dataset demonstrates patterns (a Cross-Cutting Concept).
- Hypothesize: Why might tsunami wave speeds be different for different oceans? Remember: wave speed is a property of the medium. What different properties might different oceans have? Are there some types of energy that are connected with energy seemingly "disappearing?"
Discussion & Wrap Up (10 min)
- Follow up and recap as a class: Discuss the factors that affect wave speed and compare the tsunami wave speeds to other fast things.
Assessment
A pre-class assignment is graded for completion only, not correctness. Administer using the same format throughout your course (through the LMS, turn in paper copies, guided discussion/participation in class, etc.). Consider setting the due date an hour or so before your class begins to give you time to summarize where your students sit with these concepts (this is a form of Just in Time Teaching).
The Lab(s) is/are assessed as a Science Journal, as always. Science/Lab Journals General Instructions/Rubric (Microsoft Word 2007 (.docx) 2.9MB Aug30 24)
This unit includes a Reflection. These are assigned at the conclusion of most units (typically every 1-1.5 weeks) and ask students to demonstrate higher-order thinking by putting their learning in their own words and also to apply their knowledge in new and novel situations. Reflections should be about 500 words and they should both discuss content that reflects understanding and thoughtfully reflect on the materials.
- Read Compare-Contrast-Connect: The Origin and Diversity of Surf Crafts.
Read Weird Science: Communicating Wave Sizes—Local Scale
1. What size surfboard do you think is best for beginners - large or small? What size board is best for small waves? Large waves? Explain your answers, using the vocabulary of this unit in your discussion.
2. Use the language we have developed in this course to describe issues in communicating the size of waves. Be sure to also revisit all the terminology related to error and accuracy and precision for your discussion.
This unit includes one of many Scientist Spotlights. The goal of these is to showcase an array of scientists in fields relevant to the topics of the day, some from long ago and others young and active today, together representing a diversity of people who all have a passion for science.
References and Resources
Data in this unit are from the NCEI Tsunami Data web page.
Below are some instructional resources about water waves. Instructors can watch these videos to learn more about the content in this unit and/or share these resources with interested students.
A simple example of how bottom topography can cause a wave to bend and change its speed that many students will have seen: https://www.surfertoday.com/surfing/what-is-wave-diffraction
- The video linked in this website is very instructive if an instructor wants to know more about what's happening in the photo.
- Note that this transition from deep water to shallow water isn't really going on in the middle of the (very deep) ocean, but it's still illustrative as an example of waves bending and changing speeds. We know that wave speed depends on the properties of the medium from Unit 2.1, so here's a very visual example of the medium (i.e. the depth of the ocean, obstacles like islands) changing.
Ocean wave basics from the Earth Rocks! YouTube page: https://www.youtube.com/watch?v=qogWcsW1eMg
- Students might be a little confused if you ask them to watch this as pre-class preparation because the wave speed is defined as the wavelength/period which, while true, is not how we'll be calculating the wave speed. We will be looking at the total distance traveled/time since the eruption to calculate an average wave speed between Hunga Tonga and the buoy location.
Big Waves from the Earth Rocks! YouTube page: https://www.youtube.com/watch?v=LmiIzw7zTHY
- Tsunami waves are discussed starting at 6:15, and the visualization of the tidal waves between (9:07 - 9:45) is especially worth showing to students. You can see all the wave fronts interacting and bending and arriving at different places at different times.
- This video says that tsunami waves are only caused by earthquakes, but actually Hunga Tonga's tsunamis were mostly created by falling debris together with the atmospheric pressure/shock wave. The atmospheric pressure wave was SO STRONG that low/high pressure in the atmosphere actually caused the water to rise/fall, setting off a tsunami. This atmospheric pressure wave even set off lots of smaller mini-tsunamis in ocean basins throughout the world! This is VERY unusual and was a big surprise to scientists.