Final answer:
The seafloor is exposed as seawater recedes, the sea level is increased, and wide but short waves are observed if the trough of a tsunami arrives first.
Step-by-step explanation:
If the trough of a tsunami arrives first, you will see that the seafloor is exposed as seawater recedes. This happens because the powerful force of the tsunami causes the water to be pulled back from the shore, revealing the ocean floor. Additionally, the sea level may decrease temporarily as the water retreats.
As for the waves, if the trough arrives first, you will typically observe wide but short waves. Tsunamis are characterized by their long wavelength, which results in the surge of water moving rapidly as a wall of water, often with a relatively low height compared to its width.
So, the correct answer to your question is All of above. When the trough of a tsunami reaches the coast first, you will see the seafloor exposed, the sea level increased, and wide but short waves.
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