Tsunamis - Science 8 PDF

SCIENCE AND TECHNOLOGY 8 UNDERWATER EARTHQUAKES Unit 1- Lesson 3  LEARNING OBJECTIVES At the end of the lesson, you should be able to: Demonstrate how underwater 1 earthquakes generate tsunamis. (8ES-IIb-16)  WAVES Waves (ocean waves) are...

SCIENCE AND TECHNOLOGY 8 UNDERWATER EARTHQUAKES Unit 1- Lesson 3  LEARNING OBJECTIVES At the end of the lesson, you should be able to: Demonstrate how underwater 1 earthquakes generate tsunamis. (8ES-IIb-16)  WAVES Waves (ocean waves) are disturbances in the surface of the ocean. They can be created by wind, gravity, or other displacements of water.  TSUNAMI Japanese word pronounced as “soo-nah-me” means “wave in the harbor”. Sea waves generated through underwater earthquakes reach heights greater than five meters. Can be produced by underwater landslides and underwater volcanic eruptions. WHAT CAUSES TSUNAMI?  UNDERWATER EARTHQUAKE Also known as, submarine, and undersea earthquake. It is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean.  UNDERWATER EARTHQUAKE Leading cause of tsunamis. The magnitude can be measured scientifically by the use of either the Richter scale or the Mercalli scale. HOW DOES TSUNAMI OCCUR? WHERE IS IT PRODUCED?  ORIGIN OF TSUNAMI When an earthquake, landslide, or volcanic eruption happens underwater, the ocean floor is disturbed. The disturbance will push the water upward higher than the sea level due to sudden release of intense energy.  ORIGIN OF TSUNAMI Gravity acts on the upward movement of water that results in sideways oscillations. Ocean water will be dragged away from the shore.  ORIGIN OF TSUNAMI The greater and taller waves will hit back to the shore. CHARACTERISTIC OF TSUNAMI WAVES High Speed: In deep water, tsunami waves can travel at speeds of 500-800 km/h (310-500 mph), much faster than regular ocean waves. Long Wavelength: Tsunami waves have very long wavelengths, often exceeding 100 km (62 miles), which allows them to travel across entire ocean basins with minimal energy loss. Small Amplitude in Deep Water: In the open ocean, tsunami waves typically have a small wave height (amplitude) of about 1 meter (3 feet) or less, making them difficult to detect from ships or the air. CHARACTERISTIC OF TSUNAMI WAVES Wave Shoaling: As the waves approach shallower water near the coast, their speed decreases, but their height increases dramatically due to the conservation of energy, leading to potentially destructive wave heights. Multiple Waves: Tsunamis usually consist of a series of waves (called a wave train) that can arrive minutes to hours apart. The first wave is not always the largest. Inundation: Tsunami waves can travel inland, inundating coastal areas with water, causing flooding and significant damage. CHARACTERISTIC OF TSUNAMI WAVES Backwash: After the waves crash ashore, the retreating water can pull debris and people back into the ocean, creating additional hazards. Long Duration: Tsunami waves can persist for several hours, with the potential for dangerous conditions to continue long after the initial waves have struck. LET’S WATCH THIS VIDEO!  LEARNING ACTIVITY NO. 3 “ASSESS ME, TSUNA-ME”  LET’S REFLECT! IS IT STILL NECESSARY TO KNOW ABOUT TSUNAMIS EVEN IF YOU LIVE IN THE CITY AND ARE VERY FAR FROM THE COAST? HOW EARTHQUAKES ASSOCIATED WITH TSUNAMIS?  DISCLAIMER ALERT! Not all earthquakes generate tsunamis. Usually, it takes an earthquake with a magnitude exceeding 6.0 to produce a destructive tsunami. THANK YOU! I hope you learn something new today!