海啸是如何形成的？预警分几级？如何避险？一文读懂！

Core Points - Tsunamis are powerful waves caused by storms or underwater earthquakes, typically triggered by seismic events with a magnitude of 6.5 or higher occurring at depths of less than 50 kilometers [3] - The speed of tsunamis in the ocean can reach approximately 500 to 1,000 kilometers per hour, with distances between successive wave crests potentially reaching 500 to 650 kilometers [3] - Tsunami warnings are categorized into three levels: red warning for wave heights above 3 meters, orange warning for wave heights between 1 to 3 meters, and yellow warning for wave heights between 30 centimeters to 1 meter [3] Group 1 - Tsunamis can cause significant destruction, necessitating timely warnings from relevant authorities to help people prepare and take precautions [3] - Before a tsunami strikes, individuals should move away from beaches and low-lying coastal areas, especially if they feel strong ground shaking, notice sudden water withdrawal, or hear a loud roar [7] - The destructive power of tsunamis is influenced by coastal topography, with steeper areas or "U-shaped" bays potentially amplifying wave heights [8] Group 2 - During a tsunami, vessels in deep water should not head towards the shore or shallow areas, as the waves are less destructive in deep water [9] - Individuals on boats should evacuate immediately and seek higher ground [9] - It is crucial to remain in safe areas until official signals indicate that the tsunami threat has been lifted [8]