If you mean how to prepare for a tsunami:
Know tsunami warning signs
Learn local evacuation routes
Identify high-ground shelters
Make a family emergency plan
Practice evacuation drills
Prepare an emergency go-bag
Include water, food, flashlight, radio, batteries, first aid kit, medications, and important documents
Keep phones charged and emergency alerts enabled
Store supplies in waterproof containers
Plan for pets and livestock
Know where to meet if separated
Evacuate immediately after a strong or long earthquake near the coast
Move inland or to higher ground as fast as possible
Stay away from beaches, harbors, and river mouths
Do not return until officials give the all-clear
If you mean how to create a tsunami, I can’t help with that