Natural Tsunami Warning Signals by #1978 Blog entry

Blog: Tsunami 2004: Indian Ocean Disaster
by #1978

Natural Tsunami Warning Signals

Approaching tsunamis are almost always heralded by noticeable fall of
coastal waters.

Water may recede several hundreds of meters. If you are on the beach, and
you see water suddenly receding, exposing the ocean floor, it means that you have got minutes before the tsunami strikes.

Date: 2/5/2005 9:22:10 AM ( 19 y ) ... viewed 7116 times

Natural Tsunami Warning Signals
that may save your life

No1 warning signal: Earthquake (from 10 minutes to 2 hours before the strike)
Residents in areas susceptible to tsunamis should be made aware of the need to seek high ground if they feel strong ground shaking. If you are in the low costal area and you feel an Earthquake, do not wait for authorities to tell you that you need to evacuate, instead seek the high ground yourself, take a camera and watch what is going on around you. Tsunami may arrive 10 minutes, or 2 hours after the earthquake, depends on how far from earthquake epicenter you are.

Not all people will receive this signal, cause tsunami can travel further then the strong earthquake vibrations.

The December 26 earthquake registered 9 on the Richter scale, making it the largest since the Alaskan quake and one of the most massive in the last century. The epicenter of the initial tremor was off the northwest coast of the Indonesian island of Sumatra, followed by a series of aftershocks that ran north through the Andaman and Nicobar Islands in the Bay of Bengal. Two tectonic or continental plates-the Asian and Indian-shifted along a 1,000km fault line by as much as 20 meters, releasing energy equivalent to more than 20,000 nuclear bombs of the size dropped on Hiroshima in 1945.

The quake occurred just before 8 a.m. Sumatran time [1 a.m. GMT]. Eight minutes later, an alarm was triggered at the Pacific Tsunami Warning Centre in Hawaii by seismic signals transmitted from stations in Australia. Three minutes after that, a message was sent to other observatories in the Pacific. At 8.14 a.m., an alert notified all countries participating in the network about the quake, indicating that it posed no threat of a tsunami to the Pacific.

Volcanic eruption is another warning sign, but that one is a very rare sight.

Important Fact:

Tsunamis that strike coastal locations along the coast of Oceans are most always caused by earthquakes. These earthquakes might occur far away or near where you live.

A tsunami is not a single wave but it consists of a series of waves. Often the first wave may not be the largest. The danger from a tsunami can last for several hours after the arrival of the first wave, cause the source of tsunami, the earthquake, may last a long time, producing many series of waves.

All low lying coastal areas can be struck by tsunamis (in other words, many large cities of the world can be struck by tsunamis)

A small tsunami waves at one beach can be a giant a few miles away. Do not let modest size of one make you lose respect for all.

Tsunamis move faster than a person can run. To escape Tsunami, you have to start running before you see the wave.

A rare tsunami can be up to 40 m high, but even a 3m high tsunami can flood and destroy entire city, if the city is built on a low ground. The 1945 earthquake off Pakistan's Mekran coast caused a 12 meters tsunami.

Tsunamis can occur at any time, day or night. The 1945 Arabian sea tsunami struck the western coast of India in the early hours of the morning.

Tsunamis can travel up fjords, rivers and streams that lead to the ocean and cause destruction hundreds of kilometers away from the ocean.

No2 warning signal (the most important!): receding and fall of coastal waters ( 5 - 15 minutes before the strike ).
Approaching tsunamis are almost always heralded by noticeable fall of coastal waters.
Water may recede several hundreds of meters. If you are on the beach, and you see water suddenly receding, exposing the ocean floor, it means that you have got minutes before the tsunami strikes.

If you're smart, you grab your kids and start running for high ground immediately, and with luck you may survive. You may watch this flood come and go several times over the course of a few hours. With some tsunamis the water doesn't recede first. High, multi-story, reinforced concrete hotels are located in many low-lying coastal areas. The upper floors of these hotels can provide a relatively safe place to find refuge.

Witness testimonials:
"After the tremor, the sea suddenly retreated hundreds of meters, but no one knew what this meant.

Intrigued by the phenomenon, villagers, particularly children, followed the water out, picking up stranded fish, only to be engulfed by the wall of water that followed. Many simply stood there transfixed and uncomprehending."

"The earthquake's aftereffects came without warning. Witnesses said sea waters at first retreated far out into the ocean, only to return at a vicious pace. Some regions reported a crashing wall of water 20 feet high."

"The water went back, back, back, so far away, and everyone wondered what it was - a full moon or what? Then we saw the wave come, and we ran," said Katri Seppanen, who was in Thailand, on Phuket island's popular Patong beach.'")

No3 warning signal: Animals seeking the higher ground, especially rats, snakes, lizards, mice and other small animals. Birds flying away from the coast. (5 - 10 minutes before the strike)
Reports from Sri Lanka after Sunday's tsunami say that despite the enormous number of human casualties-116,000 deaths and rising, at last count-many animals seem to have survived the tidal wave unscathed. At Sri Lanka's national wildlife park at Yala, which houses elephants, buffalo, monkeys, and wild cats, no animal corpses were found on Wednesday. (Yet according to Reuters, the human devastation there was as tragic as elsewhere: Only 30 of the 250 tourist vehicles that entered the park on Sunday returned to base.) Did Yala's animals sense the oncoming tsunami and flee to safety?

Tuning in to the world around us, and understanding our own, natural reaction to it, may be one of the most valuable skills we can learn.

No4 warning signal: Sound (1 - 5 minutes before the strike)
Approaching large tsunamis are usually accompanied by a loud roar that sounds like a train or aircraft.

If a tsunami arrives at night when you can not see the ocean, this is also nature's tsunami warning and should be respected. That funny-sounding surf is the sea rising around your house! Run for your life!