When you hear the word “tsunami” what comes to your mind? Giant waves? Coastal flooding? Or you have no clue of what it means. Whether you know about a Tsunami or not, this article will answer four points about it; what is a tsunami, what is the sign, what to prepare, and what to do when it happens.
What is a tsunami
A tsunami is a series of powerful ocean waves caused by underwater seismic activity such as earthquakes, which can destroy coastal communities. These water ripples can travel across entire ocean basins at speeds exceeding 500 miles per hour, hitting shorelines with destructive force.
Unlike regular waves, which are generated by wind and affect only the uppermost layer of water, tsunamis involve the entire water column from the surface to the seafloor. When these waves reach shallow coastal areas, their speed decreases, but their height increases dramatically.
According to the records, Japan, Indonesia, and the United States (especially coastal states like Hawaii, California, Oregon, and Alaska) are among the countries most vulnerable to tsunamis. This is primarily due to their geographical locations of active seismic zones, such as the Pacific Ring of Fire.
Signs of a Tsunami
Most people know that when a strong earthquake occurs, you must be aware of the possibility of a tsunami. However, a crucial point often overlooked is that signs can appear days before the giant waves hit.
Growing up in a country located in the Ring of Fire, I learned about earthquakes from a young age. My father once explained that there are two types of earthquakes: those originating in the ocean and those on land. He then said, “The ocean earthquake” is more dangerous due to the potential for tsunamis.
It must be underlined, that the terms “ocean earthquake” and “land earthquake” are not standard scientific terminology. Instead, earthquakes are described based on the type of plate boundaries involved.
We can understand these concepts in terms of their effects and origins:
Submarine Earthquakes (Ocean Earthquakes)
These occur beneath the ocean floor and are often associated with subduction zones where an oceanic plate is forced under a continental plate or another oceanic plate. Submarine earthquakes can move large volumes of water, potentially generating tsunamis. An example is the 2004 Indian Ocean earthquake, which triggered a massive tsunami that impacted multiple countries.
Continental Earthquakes (Land Earthquakes)
These occur within continental plates or along continental plate boundaries. They can result from various types of stress, including those at convergent, divergent, and transform boundaries. Examples include the San Andreas Fault in California (transform boundary) and the 2015 Nepal earthquake (convergent boundary).
Both continental and submarine earthquakes can potentially generate tsunamis, but submarines are most likely to cause them.
Recognizing the warning signs of a tsunami can save lives. Some of the most common signs include:
Earthquake
If you feel a strong earthquake, especially if you are near the coast, it’s crucial to be alert for a possible tsunami. Not all earthquakes cause tsunamis, but many do. Most of the time, minor earthquakes happen frequently before the major ones. If you are experiencing this, you should be prepared and avoid the coastal area.
Nothing is wrong with being cautious as long as you maintain your composure and not creating chaos. Prepare a bag that contains beneficial items for a week of surviving because you have no idea how long you will be away from the house if the worst case happens.
Unusual Ocean Behavior
The sea may suddenly recede, exposing the ocean floor, reefs, and fish, or it may rapidly rise. Both phenomena are strong indicators of an imminent tsunami. This sudden retreat of water, known as a drawdown, can precede the arrival of a tsunami by minutes to a few hours.
I remember hearing from one of the Indian Ocean tsunami survivors about this phenomenon. They noticed the coastline suddenly expanding as the sea seemed to pull away dramatically. Unfortunately, unaware that this was a sign of a tsunami, many people were surprised and casually began picking up fish stranded on the exposed shore.
Loud Roaring Sound
As the waves rush towards the shore, the loud noise can be heard reverberating like the sound of a jet engine. This sound is caused by the immense force of the underwater earthquake moving vast amounts of water, accompanied by rumbling vibrations that can be felt in the ground.
When you hear the eerie roaring sounds caused by an upcoming tsunami you probably have more or less five minutes left to evacuate if you are close to the epicenter. Tsunami waves can travel at speeds of up to 500-800 km/h (310-500 mph) in deep water and will slow down as they approach shallow coastal areas, but never underestimate their speed, because they can still arrive very quickly.
Abnormal Animal Behavior
Animals have a heightened sense of detecting danger due to their superior hearing and sensitivity to vibrations. For example, before the 2004 Indian Ocean tsunami, eyewitnesses in Yala National Park, Sri Lanka, reported elephants moving to higher ground, flamingos avoiding low-lying areas, and other animals seeking shelter and refusing to come out.
Additionally, there are records of cats behaving unusually before an earthquake in Japan. Observing animals’ behavior can provide early warnings, as they rely on their instincts for survival. If animals around you start acting strangely, it might be time to prepare for a potential disaster.
Official Tsunami Warnings
In areas prone to natural disasters, local authorities often issue alerts directly to your device, providing crucial warnings based on seismic activity and oceanographic data. If not, you can check the authorities’ updates on their social media. It’s essential to stay informed by regularly checking for updates and new information to know what actions to take next.
Things to Prepare Before a Tsunami
If you visiting beaches or residing near the coast, you likely have noticed the evacuation route signs. These signs are strategically placed to direct you to higher ground or a safe location in case of a tsunami.
Memorizing evacuation paths and safety locations is one step toward surviving a tsunami. You can also mark them on a digital map on your device, or, it’s also wise to keep a physical map with these routes noted for reference if something unexpected happens like losing electrical power. Additionally, follow social media or news sources specialized in natural disasters to monitor the updates in your area.
You need to bring the emergency kit with you when evacuating. It is highly recommended to prepare them previously (whenever you read this, just start to prepare them even though there is no emergency), try to put all of them in one bag, and keep them in a location you can find quickly during an emergency. If you haven’t prepared them yet, and the time is ticking, at least grab the top three items or one of the top three on this emergency list below:
Bottle of Water
Humans can survive with only water for two to three weeks. After surviving a tsunami, seek shelter or ensure your current location is safe from further dangers. Search and Rescue teams may take days or weeks to find all survivors, so be prepared to survive for as long as possible if you can’t move. Avoid dehydration by conserving your water intake, and do not drink dirty water due to contamination and bacteria that can worsen your condition. Without consuming food, your muscle mass and fat will decrease, making your body weaker. Therefore, rest as much as possible when you’re not searching for help
Practical Tools
In a tsunami emergency, it’s crucial to have one or more of these items, such as a flashlight to signal rescuers and provide light at night, a whistle to draw attention to your location, and a pocket multi-tool for various survival tasks.
First Aid Kit
The story of the tsunami survivors has highlighted the importance of the First Aid Kit, placing it in the top three essential items. Even if you survive the disaster, you may sustain injuries that require immediate attention. Ignoring open wounds or scratches can lead to infections. Therefore, bringing a First Aid Kit equipped with bandages, antiseptic wipes, adhesive tape, and antibiotics is crucial.
Food
Food provides you with energy, much like a fire in a furnace that furnishes warmth and strength during harsh winter. Pack long-lasting, durable food items such as canned food, vacuum-sealed trailed mix, or energy bars. These types of food will sustain you for enough amount of time, giving you the energy to find help while the situation is conducive. Try to limit your food supplies to no more than three days to avoid becoming burdened during the evacuation.
Blanket or Sleeping Bag
You never know how long you will have to wait for help to arrive. Quality sleep is essential to replenish your energy. Therefore, bringing a blanket or sleeping bag can provide more comfort if you need to sleep outside or in a place with limited bedding.
Important Documents
Having your identification card, credit card, emergency contact information, and other important documents readily accessible will save you a lot of time once everything stabilizes. Be sure to store these items in a waterproof container to protect them from damage.
The items listed above are essential for a tsunami emergency kit. One more item to consider is your smartphone. Given that most people carry their phones everywhere, you will likely have them with you during an evacuation. However, it’s important to understand that a smartphone can’t be relied upon as an emergency kit item. If it loses signal or runs out of battery, it will be useless in critical moments. If you accidentally leave your smartphone behind, do not risk to return to retrieve it.
What to Do When a Tsunami is Coming
After understanding the signs and what to prepare, it’s the moment for you to know the appropriate actions to take if you find yourself in such a situation:
Move to Higher Ground
Immediately seek higher ground or move as far as possible from the coastal area. The highest tsunami recorded within the past 100 years was the 2004 Indian Ocean tsunami, which reached approximately over 30 meters (100 feet) in some areas. It is worth noting that the wave height will decrease as it reaches the coastline, but it is still better to evacuate to the highest ground near you as soon as possible.
Follow Evacuation Routes
As mentioned in the preparation section above, familiarize yourself with these routes. Many seaside areas have designated evacuation routes and zones which will help you in an emergency.
Listen to Authorities
Pay attention to official warnings and instructions from local authorities. Do not wait for visual confirmation of the tsunami, evacuate immediately upon receiving a warning.
Do Not Return Immediately
Tsunamis come in waves, and the first wave is often not the largest. Stay away from the affected areas until authorities declare it safe. After the initial impact of the tsunami, subsequent waves can continue to pose a threat to safety and infrastructure.
There is always this possibility…
If you are still in the coastal area when a tsunami is approaching in just a few minutes. Try to look for a sturdy building nearby and run to its highest point, such as the top floor or the roof. Avoid weak or shaky structures, as they are likely to be destroyed by the force of the waves.
Another way to survive is by clinging to large, floating, or sturdy objects, such as car rooftops, trees, or even refrigerators. Many tsunami survivors have held onto floating objects they could reach. For instance, an Indonesian woman climbed and clung to a coconut tree for days during the 2004 Indian Ocean tsunami before she was rescued, and 60-year-old Hiromitsu Shinkawa clung to his refrigerator to stay afloat when the tsunami hit Japan in 2011.