Tsunami: Nature’s Terror Group 2 Project Produced by Frederick Handy, Christopher Wilson, Azadeh Akbari, and Ciara Kelty

Tsunami: Nature’s TerrorGroup 2 Project

Produced by Frederick Handy, Christopher Wilson, Azadeh Akbari, and Ciara Kelty

What is an Tsunami Group 2 Project

An Tsunami generate by a earthquake

Tsunami is a set of ocean waves caused by any large, abrupt disturbance of the sea-surface.

If the disturbance is close to the coastline, local tsunamis can demolish coastal communities within minutes. A very large disturbance can cause local devastation AND export tsunami destruction thousands of miles away.

The word tsunami is a Japanese word, represented by two characters: tsu, meaning, "harbor", and nami meaning, "wave“.

Tsunamis are often called "tidal waves" as they may resemble a non-lunar-tidal rush of rapidly rising water, rather than big cresting waves reaching the shore. However, the term is discouraged by oceanographers since tsunamis are not related to tides.

What is an Tsunami Group 2 Project

Notable Tsunami’s in our history

Causes of Tsunami Group 2 Project

A tsunami can be generated by any disturbance that displaces a large mass of water, such as an earthquake, landslide or meteor impact.

Tsunamis are most commonly generated by earthquakes in marine and coastal regions. Major tsunamis are produced by large (greater than 7 on the Richer scale), shallow focus (< 30km depth in the earth) earthquakes associated with the movement of oceanic and continental plates.

They frequently occur in the Pacific, where dense oceanic plates slide under the lighter continental plates. When these plates fracture they provide a vertical movement of the seafloor that allows a quick and efficient transfer of energy from the solid earth to the ocean


When a Tsunami begins an area of the oceanic plate is being forced down into the mantle by plate tectonic forces. The friction between the subducting plate and the overriding plate is enormous. This friction prevents a slow and steady rate of subduction and instead the two plates become "stuck


As the stuck plate continues to descend into the mantle the motion causes a slow distortion of the overriding plate. The result is an accumulation of energy very similar to the energy stored in a compressed spring. Energy can accumulate in the overriding plate over a long period of time – decades or even centuries


Energy accumulates in the overriding plate until it exceeds the frictional forces between the two stuck plates. When this happens, the overriding plate snaps back into an unrestrained position. This sudden motion is the cause of the tsunami - because it gives an enormous shove to the overlying water. At the same time, inland areas of the overriding plate are suddenly lowered.


The moving wave begins travelling out from where the earthquake has occurred. Some of the water travels out and across the ocean basin, and, at the same time, water rushes landward to flood the recently lowered shoreline.


Tsunamis travel swiftly across the open ocean. The map below shows how a tsunami produced by an earthquake along the coast of Chile in 1960 traveled across the Pacific Ocean, reaching Hawaii in about 15 hours and Japan in less than 24 hours.


Many people have the mistaken belief that tsunamis are single waves. They are not. Instead tsunamis are "wave trains“ consisting of multiple waves. The chart below is a tidal gauge record from Onagawa, Japan beginning at the time of the 1960 Chile earthquake. Time is plotted along the horizontal axis and water level is plotted on the vertical axis. Note the normal rise and fall of the ocean surface, caused by tides, during the early part of this record. Then recorded are a few waves a little larger than normal followed by several much larger waves. In many tsunami events the shoreline is pounded by repeated large waves.


Other Causes of Tsunami’s

Volcanic Eruption - Although relatively infrequent, violent volcanic eruptions represent also impulsive disturbances, which can displace a great volume of water and generate extremely destructive tsunami waves in the immediate source area. Volcanic disturbances can generate waves by the sudden displacement of water caused by a volcanic explosion, by a volcano's slope failure, or more likely by a phreatomagmatic explosion and collapse and/or engulfment of the volcanic magmatic chambers. The majority of tsunamis that occur in the Pacific Ocean happen around the “Ring of Fire” Area surrounding the Hawaiian Islands. The periphery has also been dubbed the 'Ring of Fire' because of the extraordinarily high number of active volcanoes and seismic activity located in the region. Since 1819, over 40 tsunamis have struck the Hawaiian Islands. One of the largest and most destructive tsunamis ever recorded was generated in August 26, 1883 after the explosion and collapse of the volcano of Krakatau (Krakatau), in Indonesia. This explosion generated waves that reached 135 feet, destroyed coastal towns and villages along the Sunda Strait in both the islands of Java and Sumatra, killing 36, 417 people



Landslides – resulting in rockfalls, icefalls, or underwater (submarine) landslides or slumps can generate displacement of water to create a tsunami. More often than naught, submarine landslides are often caused by earthquakes, large and small, therefore strengthening the force of an earthquake induced tsunami. The most notable example of a landslide-induced tsunami can be traced to Southern France in the 1980’s where the movement of a significant amount of earth for the construction of an airport triggered an underwater landside, which resulted in destructive tsunami waves hitting the harbor of Thebes.

Illustration of a underwater landslide causing a Tsunami


Extraterrestrial Collision – Tsunamis caused by extraterrestrial collision (i.e. asteroids, meteors) are an extremely rare occurrence. Although no meteor/asteroid induced tsunami have been recorded in recent history, scientists realize that if these celestial bodies should strike the ocean, a large volume of water would undoubtedly be displaced to cause a tsunami. Scientists have calculated that if a moderately large asteroid, 5-6 km in diameter, should strike the middle of the large ocean basin such as the Atlantic Ocean, it would produce a tsunami that would travel all the way to the Appalachian Mountains in the upper two-thirds of the United States. On both sides of the Atlantic, coastal cities would be washed out by such a tsunami. An asteroid 5-6 kilometers in diameter impacting between the Hawaiian Islands and the West Coast of North America, would produce a tsunami which would wash out the coastal cities on the West coasts of Canada, U.S. and Mexico and would cover most of the inhabited coastal areas of the Hawaiian islands.


Impact of Tsunami Group 2 Project

The impact of Tsunami can be felt not only through the sheer force of its power. But itCan have a ripple effect on many aspects of those who live through the event.


One example of how tsunami ‘s impact is its effect on countries during the 2004 Tsunami. The epicenter of the earthquake was situated off the Indonesian island of Sumatra is fully exposed to the Indian Ocean. Some twenty countries from 2 continents have their coastlines along the Indian Ocean and as such, it was not surprising that countries as far as those in Africa were affected as well.

Damage to Countries


The total notable death toll during the 2004 Tsunami


Economical Impact

One example of the economical impact was during the 2004 Tsunami where many indigenous fishermen and for the fishing industry as a whole, the tsunami spells more than just a natural disaster. These fishermen, most of whom have no other skills, can no longer depend on fishing as a means of survival for the time being. The fish stock has been depleted, as would the fishermen‘s money. Also, the many of the fishermen's families would have lost their sole breadwinners, together with the fishing boats and equipment, adding on to their already heightening problems. The tsunamis that affected the coast of Thailand, Indonesia and the Maldives has destroyed much of the marine biology there, also damaging the ecosystem severely.


Infrastructure Impact

•When the sheer force of a incoming tsunami obliterates everything in its path, it also clears away roads and railways, hampering rescue efforts.

•Tsunami’s can cause a impact on health through broken sewage and water pipes, contaminating water and food sources .

•Subsequently, diseases such as cholera, typhoid, dysentery and dengue then become more rampant. The rotting corpses left behind by the tsunami also helped to spread diseases to the survivors.

•Crops, settlements, trees, birds, fishes, wildlife, properties were severely destroyed, with power and communications disrupted, adding on to the daunting task of rescue work. People clung on to trees for their dear life; some were rescued, but some were also swept away, right in front of their relatives and family members. The emotional and mental trauma would remain in all those affected for years, even if they had escaped a watery


Environmental Impact •Precious coral reefs and mangrove areas would have been crushed by the huge tsunami waves that have devastated southern Asia, an environmental and economic setback that could take years to reverse.

•The reefs around Sri Lanka and Phuket have been severely damaged due to them having to bear the brunt of the forceful walls of water. When the waves get close to shore, their height is amplified and they release all their energy, decimating everything in their paths. The atolls of the alluring Maldives and the southern Thai islands (including Mangrove areas that act as nursery habitats to fish and shrimp) were also destroyed by the strong waves.

•According to scientists, reef-forming coral grows only about 0.5 cm, or 1/5 inch a year, thus for the seaside resorts on the numerous affected islands to regain their previous splendor could take several years to a decade. The worst marine damage was likely to have been concentrated 100m to 1km from shore. Fortunately, large sea mammals such as whales and dolphins probably suffered little impact.

Physics of Tsunami Group 2 Project

• Tsunami can be explained by phenomenon of wave traverse; its energy is function of height (amplitude) and speed where the height depends on the wavelength.

•A tsunami has wavelength in order of hundreds kilometers behave as shallow-water wave. A wave becomes a shallow-water wave if ratio of depth of water and wavelength is lesser then 0.05.

•The speed of shallow-water wave is square root of (g*d), g is gravity acceleration and d is depth of water. Imagine, at the depth 10 km in India Ocean, a tsunami will have initial speed around 300 m/sec or around 1000 km/hours. The speed decrease as depth increase when move toward beach. However, its energy tends constant.

•This follows the energy loss rate of transversal wave is inverse with its wavelength; i.e. the bigger wavelength the smaller energy loss. Then energy of tsunami tends constant.

•Because of the energy constant, decreasing of speed will increase the height. Scientists observe with speed of 1000 km/hours toward beach, tsunami can have height 30 meter.


Tsunamis are identified as shallow-water waves. Do not entangle shallow-water waves with wind-generated waves. They are of two different types. An example of a wind-generated wave are the waves you have seen at the beach. Wind-generated waves usually have a period of 5 to 20 seconds and a wavelength of 100 to 200 meters (300 to 600 ft). A tsunami can have a period ranging from 10 minutes to 2 hour and experience a wavelength of 300 miles (500 km) or more. Tsunamis are characterized as shallow-water waves due to their large wavelengths. The speed of a shallow-wave length follows:

Let S = Speed Let g = acceleration of gravity (32ft/sec/sec, 9.8m/sec/sec) Let d = depth of water S = (g * d)^(1/2)

The rate at which a wave depreciates its energy is inversely related to its wavelength: Let R = The rate at which a wave loses its energy Let L = Wave Length R = (1/L)


We can determine the Rate of Loss Energy by using the formula. Below is a interactive calculator to show the process is done:


We can determine the Speed of the Tsunami by using this formula. Below is a interactive calculator to show the process is done:

For example If the ocean is 20,000 feet deep (6100 m), S=[(9.8m/s/s)* (6100m)]^(1/2)S=244.5 m/s


Through these formulas we can better understand the physics of a Tsunami since:

• Regarding Energy wave lost the larger the wave the less energy is lost and Deeper water gives the Tsunami greater speed with greater distance including limited energy loss.

•Regarding the Speed of the wave deeper water equals to more speed and ability to travel distance for the Tsunami. So if a Tsunami originates in deeper water to has a greater chance to reach more coast land vs. a Tsunami that originates inland(via landslide above ground).


In the Physics of a Tsunami the Important Factors in its creation are:

1.The Depth of the water (slow in shallow water and fast in deep water)

2.Its energy depreciation (affects wave length)

3.Rate of speed (ability to travel longer distance)

Tsunami Simulation Group 2 Project

What would it be like if a Tsunami hit a east coast city like Philadelphia?

By looking at the physics of a Tsunami we can calculate the cause, impact,and characteristics of our fictional Tsunami


How would it originate

•Most likely an Tsunami which could hit our eastern coastline would originate due to a large

landslide.

•Potential landslides sites off the coast of Virginia and North Carolina could cause the already unstable continental slope to create Tsunami’s as high as 18 feet.


How would it reach our coast

•In knowing the physics of an Tsunami the depth of the ocean plays a part in the speed and power it would hit our coast.

•The average ocean depth of the Atlantic Ocean is 3872 meters.

•In this depth a Tsunami originating in the Atlantic Ocean will have an average speed of 708km/h or 440mph.

This simulation shows an example of the speed of a Tsunami wave moving away from the originating site.


The impact of an Tsunami hitting our coast

• Massive lost of life • Loss of local government infrastructure• Failure of power supply • Failure of communication systems • High environmental impact affecting water supply, food , and risk of disease.

1998 Tsunami Affecting Papua New Guinea On July 17th, 1998, an earthquake measuring 7.1 on the Richter scale occurred about 15 miles just of the coast of northern Papua New Guinea, an island nation located in the southwestern Pacific Ocean just south of Indonesia and north of Australia. While the magnitude of the quake was not large enough to create the tsunami directly, it is believed the earthquake generated an undersea landslide, which in turn caused the tsunami. Following the earthquake, a tsunami with waves reaching 12 meters (40 feet) hit the Papua New Guinea coast within 10 minutes, destroying the villages of Arop and Warapu. An estimated 2,200 people were killed.

Example of earthquake wave reaching New Guinea coastline

2004 Indian Ocean TsunamiThe 2004 Indian Ocean earthquake, which had a magnitude of 9.0 to 9.3, triggered a series of lethal tsunami on December 26, 2004, that killed approximately 300,000 people (including 168,000 in Indonesia alone), making it the deadliest tsunami as well as one of the deadliest natural disasters in recorded history. It also had the second-largest earthquake in recorded history. The initial surge was measured at a height of approximately 33 meters (108 feet), making it the largest earthquake-generated tsunami in recorded history. The tsunami killed people over an area ranging from the immediate vicinity of the quake in Indonesia, Thailand, and the north-western coast of Malaysia, to thousands of kilometers away in Bangladesh, India, Sri Lanka, the Maldives, and even as far away as Somalia, Kenya, and Tanzania in eastern Africa. This is an example of a teletsunami which can travel vast distances across the open ocean, in this case, it is an inter-continental tsunami. Tsunami waves 2.6 meters tall were reported even in places such as Mexico, nearly 13,000 km away from the epicenter. The energies for these waves travel along fault lines and becoming concentrated therefore travelling further.

1964 Tsunami Affecting the West Coast of North AmericaNow known as the Good Friday Tsunami, the west coast, especially in the state of Alaska, was affected by a tsunami that was the most devastating ever in the continent of North America. On March 28th 1964, the United States experienced its biggest earthquake in history near College Fjord in Prince William Sound of the coast of Alaska that measured 9.2 on the Richter scale. The earthquake lasted for three to five minutes in most areas with jolting of the ocean floor creating large tsunamis. Although the earthquake did cause some destruction, the majority of death and property damage was caused by the resulting tsunami. The small Alaskan coastal communities of Girdwood, Portage, Vladez, and some native villages were absolutely decimated. There were a total of 106 people killed in Alaska due to the tsunami waves which reached heights of 11.5 meters (38 feet). The tsunami traveled south along the west coast to impact the Canadian province of British Columbia. The mainland coast and Vancouver Island were affected where houses were seen being washed away to sea. Considerable damage was also felt in Crescent City, California where eleven people lost their lives. Even Hawaii, thousands of kilometers away felt the impact of the tsunami.

The waterfront at Seward, Alaska after the earthquake. Video of 1964 Tsunami aftermath

Documents

Tsunami: Nature’s Terror Group 2 Project Produced by Frederick Handy, Christopher Wilson, Azadeh Akbari, and Ciara Kelty