News: Recently, a massive magnitude 8.8 earthquake struck off the coast of Russia’s Far Eastern Kamchatka Peninsula, triggering tsunami waves as high as 16 feet.
About Tsunami
- A tsunami is a series of big waves caused by something that suddenly moves a large amount of water in the ocean—like an earthquake.
- Most tsunamis happen when an earthquake occurs under the ocean, or very close to the coast.
- When the sea floor shakes, it can push a lot of water up or down very suddenly. This movement starts the tsunami waves.
What Kind of Earthquake Causes a Tsunami?
- Depth of the Earthquake:
- If the earthquake is shallow (close to the surface, between 0 and 70 km deep), it is more likely to cause a tsunami.
- Shallow quakes keep more of their energy and can move the sea floor a lot.
- Deep earthquakes (below 70 km) lose energy before reaching the sea floor, so they don’t usually cause tsunamis.
- Type of Movement:
- Earthquakes caused by reverse faulting (where one part of the Earth’s crust moves up over another) can push the sea floor up or down.
- This vertical movement moves a huge amount of water, starting tsunami waves.
- This usually happens in subduction zones, where one tectonic plate slides under another.
- Magnitude (Strength):
- Tsunamis are mostly caused by strong earthquakes — magnitude 7.0 or higher.
- The biggest and most dangerous tsunamis come from earthquakes above 8.0.
- Stronger earthquakes release more energy, so they move the sea floor more and create larger waves.
Where do these earthquakes happen often?
- Tsunami-causing earthquakes mostly happen at tectonic plate boundaries, especially at convergent boundaries (where one plate goes under another).
- Example: The Kuril-Kamchatka Trench near Russia is a dangerous area. There, the Pacific Plate is being pushed under the Okhotsk Plate, making it prone to big earthquakes and tsunamis.
