Weekday Weather 101 Lesson: Tsunamis
In light of this very challenging time and with students out of the classroom, the Doppler 9&10 Weather Team wants to help bring weather lessons to you at home! Doppler 9&10 Meteorologist Haleigh Vaughn and Forecaster Samantha Jacques will be providing weather-related lessons during the week. Haleigh Vaughn will discuss weather lessons and provide a worksheet, while Samantha Jacques will share hands-on science experiments. You can follow along with the Weekday Weather Lessons by completing the weather worksheet at the bottom of the article. To find the hands-on science experiments, search “Science with Samantha” on our homepage. You can also click on “The Four” to find all of our science and weather-related articles.
Today’s lesson is about … tsunamis! According to the National Ocean Service, tsunamis are a series of giant waves typically caused by earthquakes. They can be created by volcanic activity, landslides, certain types of weather, or near-earth objects (ex: astroids, comets). However, those are less common! Out in the middle of the ocean, the tsunami waves do not become dramatically larger. As the waves travel closer to the land, the waves become higher and higher as the ocean depth decreases. The speed of a tsunami wave depends on ocean depth, not the distance from the source of the wave. Believe it or not … the National Ocean Services states that “tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters.”
Another interesting fact is that people occasionally call tsunamis “tidal waves.” However, tsunamis have nothing to do with the tides. This term is discouraged by oceanographers!
Tsunamis can vary in height and strength! Typically, the stronger the earthquake or volcanic eruption, the stronger the tsunami can be. But, not all earthquakes can create tsunamis. According to the NWS Jetstream Online School, tsunamis typically occur when an earthquake has a magnitude stronger than 7.0, occurs near the ocean, and is less than 62 miles below the Earth’s surface.
You might be wondering how earthquakes occur! Well, earthquakes strike in parts of the world because of tectonic plates. The Earth’s surface is covered in tectonic plates. The photo on the left provides a picture of Earth’s tectonic plates, courtesy of The Geological Society. These tectonic plates are constantly moving. At times, these plates can get “snagged” on each other. This causes tension, pressure, and stress to build. Eventually when the stress becomes too great, the tectonic plates slip past each other. This releases a tremendous amount of energy, causing the Earth to shake and crack. This is when earthquakes occur! According to the National Weather Service, these cracks are called faults. This is where earthquakes are most likely to occur.
Tsunamis can create serious destruction, and people often lose their lives.
According to the NWS JetStream Online School, the deadliest tsunami in history happened on December 26, 2004. An earthquake with a magnitude of 9.1 struck near the island of Sumatra in the Indian Ocean, creating a tsunami that reached 167 feet high. For perspective, that’s over half the size of a football field. The tsunami created destruction in seventeen countries in parts of Asia and Africa. About 230,000 people died, and there were roughly $13 billion dollars in economic losses. You can see a photo of the destruction to your right. This photo was taken in Banda Aceh, Indonesia after the 2004 tsunami.
Another less common way for tsunamis to occur is through the weather! Air pressure disturbances often associated with fast-moving weather systems can generate tsunamis. These are called “meteotsunamis”. This phenomena can happen when a strong line of storms, or squall lines, pass over a body of water. We have this happen occasionally here in Northern Michigan! Most meteotsunamis are too small to notice, but some can create some serious flooding and damage.
As many of you can recall, we had a meteotsunami event on April 13, 2018 near Manistee, Ludington, and Pentwater. Due to the topography of the land, the lake depth, the strong line of storms passing over, and the air pressure change, a meteotsunami occurred. Plenty of flooding and coastal erosion happened.
To follow along at home, you can fill out this Weather Worksheet! Write your name and hometown, fill out the answers, and submit your work! Your worksheet can be emailed to firstname.lastname@example.org. Your worksheet might just be shared on social media!