How a Tsunami forms and the difference with “watch” & “warning”
Understanding Tsunami Alerts in Puerto Rico
When an earthquake occurs near or across the ocean, emergency agencies may issue a tsunami alert for coastal communities. Knowing what each alert means can help you make informed decisions and avoid unnecessary panic.
This guide explains the different types of tsunami alerts, what actions you should take, and why staying informed is important during any emergency.
What Is a Tsunami?
A tsunami is a series of powerful ocean waves caused by a sudden displacement of water. Most tsunamis are triggered by large undersea earthquakes, but they can also result from underwater landslides, volcanic eruptions, or, in rare cases, meteorite impacts.
Unlike normal ocean waves caused by wind, tsunami waves can travel across entire oceans at very high speeds. As they approach shallow coastal waters, they slow down and grow taller, increasing the risk of flooding and strong currents.
How Does a Tsunami Form?
Most tsunamis begin with a powerful underwater earthquake. When the ocean floor suddenly shifts,
it pushes a massive amount of water upward, creating a series of waves that travel outward in all
directions across the ocean.
An Underwater Earthquake Occurs
A strong earthquake beneath the ocean causes the seafloor to rise or fall suddenly,
displacing millions of gallons of water.
Waves Travel Across the Ocean
The displaced water forms long waves that can travel across the ocean at speeds
exceeding 500 miles (800 kilometers) per hour in deep water.
The Waves Reach the Coast
As the waves enter shallow water, they slow down but grow much taller,
increasing the risk of flooding and dangerous currents along the shoreline.
A tsunami is not a single wave. It is a series of waves that can continue arriving for several hours,
which is why officials recommend staying away from the coast until the warning has been lifted.
Understanding Tsunami Alert Levels
Emergency agencies use different alert levels depending on the level of risk. Here is what each one means and what you should do.
Tsunami Warning
What it Means
A tsunami capable of causing dangerous coastal flooding or powerful currents is expected or already occurring.
What You Should Do
- Evacuate coastal areas immediately.
- Move to higher ground or inland.
- Follow instructions from local emergency officials.
- Do not return until authorities declare the area safe.
Tsunami Advisory
What it Means
Strong ocean currents and dangerous waves are expected, but widespread flooding is not anticipated.
What You Should Do
- Stay away from beaches, harbors, marinas, and coastal waters.
- Do not enter the ocean.
- Continue monitoring official updates.
Tsunami Watch
What it Means
A tsunami is possible based on an earthquake or other event, but officials are still determining whether a dangerous wave has been generated.
What You Should Do
- Stay informed through official sources.
- Review your evacuation plan.
- Be prepared to act if the alert is upgraded.
Information Statement
What it Means
An earthquake has occurred, but there is little or no threat of a tsunami for your area.
What You Should Do
- No protective action is required.
- Continue monitoring official information if conditions change.
Why Understanding Alerts Matters
Receiving an emergency notification can be stressful, especially when little information is available. Understanding the difference between a Watch, Advisory, Warning, and Information Statement helps you respond appropriately instead of reacting out of fear or confusion.
The goal of emergency alerts is to provide enough time for people to prepare, protect themselves, and follow instructions from local authorities.
Stay Informed During an Emergency
During any tsunami or earthquake event:
- Follow official emergency management agencies.
- Listen to local emergency broadcasts.
- Monitor weather and emergency alerts on your phone.
- Avoid spreading unverified information on social media.
Be Prepared Before the Next Emergency
Preparing before an emergency is one of the best ways to protect yourself and your family.
A few simple preparations today can make a significant difference when every minute counts.
Know Your Evacuation Route
Identify the nearest evacuation route and higher ground before an emergency occurs.
Emergency Contacts
Keep a list of family members, neighbors, and emergency services.
Flashlight & Batteries
Have multiple flashlights and extra batteries available.
Food & Water
Store enough drinking water and non-perishable food for several days.
First Aid Kit
Include medications, bandages, and other essential medical supplies.
Emergency Radio
Use a battery-powered or hand-crank radio to receive official updates.
Portable Chargers
Keep power banks fully charged for your mobile devices.
Important Documents
Store copies of IDs, insurance policies, and medical information in a waterproof container.
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