Tsunami

By

Harish Kumar Lekkala

117R1A0132

What is a tsunami….

Tsunami•The term tsunami comes from the Japanese ; i.e  (tsu) meaning "harbour " and ; ( nami ) meaning “wave” means “harbour wave”. Tsunamis are not created from the wind! Earthquakes, landslides, volcanic eruptions, explosions, and even an impact from space, such as meteorites, can generate tsunamis. Tsunamis can destroy coastlines, causing property damage and loss of life. A lot of the loss of life is caused by drowning.

•As the tsunami leaves the deeper water of the open ocean and travels into the more shallow waters near the coast, As the tsunami heads toward the shallow water the speed of the tsunami will decrease but the energy of the tsunami will stay the same and the wave grows bigger this happens because its called a "shoaling" effect.

As the tsunami reaches the shore, a rapidly falling or rising tide may appear. Undersea features and the slope of the beach helps change the tsunami as it approaches the shore. Not very often are tsunamis large breaking waves. Sometimes they break far offshore. If the tsunami moves into a bay or river a bore (a step-like wave with a steep breaking front) can occur. The water level will rise from 50-100 feet. This flood can travel 1000 feet or more inland. When the water retreats back out to the ocean all the damaged objects will get drag back into the ocean . Run-up height is the maximum vertical height onshore above sea level. Since tsunamis are caused by earthquakes, A tsunami is caused by a earthquake therefore we can not predict when there gonna happen and the intensity of the tsunami. You can never tell exactly when it’s finished because there are after shocks more earthquakes and local tsunamis from landslides.

Schematic plate tectonic setting for tsunami

generation

NOAACommonly, in mega-thrust earthquakes, a

very large area of the ocean floor is uplifted

TRENCH

Tsunami wave propagation characteristics – note that as water depth becomes smaller, waves slow down, become shorter wavelength, and have larger amplitude.

NOAA

Water waves animation

Direction of propagation

Tsunami Sources

• Earthquakes (e.g. Sumatra, 2004: >200,000 people killed; Papa New Guinea, 1998: ~3,000 people killed)

• Volcanic eruptions (e.g. Krakatoa, 1883: tsunamis killed 30,000 people; Santorini, 2002).

• Mass Movement (e.g. Alaska, 1958: waves up to 518 m high formed in Lituya Bay).

• Extraterrestrial Impacts - large impacts have the potential to create enormous tsunamis.

Tsunami Locations

• Large subduction zones produce the most tsunamis. The Pacific, rimmed with subduction zones, has the most tsunamis.– Pacific ~ 80%– Atlantic ~ 10%– Remaning area ~ 10%

Tsunami Travel Times (Hawaii)

From Merritts et al., 1998

Most Destructive recent Tsunamis

1975 Hawaii1929 Grand Banks

1960 Chile 1996 Peru

1964 Prince William Sound

1946 Aleutian

1957 Aleutian

1952 Kamchatka 2004 Indian Ocean tsunami

Tsunami Statistics (NOAA)(Dec. 26, 2004 tsunami resulted in over 200,000 deaths)

Tsunami Statistics

Propagation, Response and Warning Times for the M9.0 Sumatra EQ

16 minutes after OT

P S

Northern SumatraTsunami inundation spreadsfurther along the Sumatran coast and reaches theNicobar Islands

NEICFirst automatic location releasedat NEIC

Pager notification to about 10people in the USGS

PTWCConfers with NEIC on the location and magnitude of theEarthquake

Release Tsunami Information Bulletin

1929 Grand Banks Tsunami

November 18, 1929, at approximately 5:00pm, Newfoundland  experienced an Earthquake off the coast of Grand Banks, Newfoundland. That's when a  tsunami was started by an under water landslide and the earthquake, which was a Richter magnitude of 7.2 with an epicenter of 44.5°N, 56.3°W. After the tsunami hit it caused $400,000 in damage and killed 29 people, the biggest death rate to occur an in Canada from an earthquake.

This tsunami`s  most damage was caused by the underwater landslide. The landslide added to the size of the tsunami and damaged many kilometers of 12 different transatlantic cables. The most of the economy`s money was spent on the repair costs  the for transatlantic cables. Unaware of the danger coming from the sea, the communities of Burin Peninsula, Newfoundland, there was a huge amount of damage and loss of 29 lives. The tsunami was spotted as far as South Carolina and Portugal.

In 1952 American scientists from Columbia University put together the pieces of the broken cables that led to the landslide and the first documentation of a turbidity current. Scientists are looking at layers of sand believed to be deposited by other tsunamis in an effort to determine the occurrence rates of large earthquakes. One sand layer, were thought to be deposited by the tsunami in 1929, in Taylor's Bay they found 13 cm below the turf line. The occurrences of large tsunamis, such as the one in 1929, are dependent upon deposition of sediments offshore because it was the landslide, which made the tsunami so powerful. The deposition of such a large volume of sediments will take awhile before there is enough to for an underwater landslide of size as in 1929.

1946 AleutianApril 1, 1946, at 12:29 GMT, an earthquake shook the Aleutian Islands of Alaska. There was a Pacific-wide tsunami that had been started by the earthquake, The tsunami had a surface-wave magnitude of 7.8, an epicenter of 52.8° N, 163.5° W, and a focal depth of 25 km. The tsunami took the lives of more than 165 people.

There was one structure affected by the tsunami it was a new built Scotch Cap lighthouse on Unimak Island, Alaska. In the Hawaiian Islands was one of the hardest hit locations, by the tsunami. Pololu Valley it recorded the highest run-up of 12.0 m. Hilo was the city that received the most costly damage on the Island of Hawaii. The tsunami arrived at Hilo 4.9 hours after it originated in the Aleutian Islands and the run-up was measured at 8.1 m. Hilo received approximately $26 million in damage and 96 people lost their lives.

The large number of deaths from this event brought the people to realize that a warning system was necessary to make sure the safety of the population. August 12, 1948, a plan was approved and the Seismic Sea Wave Warning System was established. They changed the Pacific Tsunami Warning System.

1952 KamchatkaOn November 4, 1952, at approximately 5:00pm, an earthquake occurred off the coast of the Kamchatka Peninsula, Russia. The tsunami was started by the earthquake that traveled pacific wide, it had a focal depth of 30 km, a magnitude of 8.2, and an epicenter of 52.8° N, 159.5° E. In Hawaii six cows died but no human lives were lost. Damage was estimated in the range of $800,000- $1,000,000 (in 1952).

The Hawaiian Islands had far worse damage. The waves destroyed piers and boats, knocked over telephone poles alone with their lines, washed away beaches, and flooded homeowners lawns. A cement barge was thrown into a freighter in Honolulu Harbor. In Hilo Bay the bridge that connects Coconut Island to the shore, was lifted off its foundation and then smashed down into the water. This was caused by one of the waves. At Coconut Island the run-up was 12 feet. At Hilo the run-up was 11 1/2 feet a new record. At Reed's Bay, the water level was as high as 11 feet. Most all the other coastal cities of Hawaii, the water rise wasn’t noticeable. The destruction vary from place to place. Without knowing the size of damage, Hawaii had to warn homeowners to keep them away from the shoreline until was safe to go home.

Midway Island’s roads were flooded, because of the Kamchatka tsunami 3,000 km away from the origin.

Photograph Credit: U.S. Navy. Source: National Geophysical Data Center.

1957 AleutianMarch 9, 1957, at 2:22 GMT, an earthquake hit south of  Andrean of Islands, in the Aleutian Islands of Alaska. It was Pacific-wide tsunami that was started by the earthquake, which had a surface-wave magnitude of 8.3, an epicenter of 51.5° N, 175.7° W, and a focal depth of 33 km. In this event there were no lives lost, the Hawaiian Islands had received approximately 5 million dollars.

The Island of Kauai, Hawaii, was hit by this tsunami twice as bad than by the Aleutian Islands tsunami in 1946. Houses were washed out and destroyed at Wainiha and Kalihiwai. At Haena,  The heights of the waves reached about 16 m. At Hilo, Hawaii, the run-up was reached 3.9 m. In Hilo Bay, Coconut Island was covered by 1 m of water and the bridge connecting it to shore was destroyed.

There was major a  wave at Laie Point on the Island of Oahu, Hawaii. The northwest side of the Hawaiian Islands received high levels of water. Both the 1946 and 1957 tsunamis occurred  at pretty much the same place (the Aleutian Islands). The 1957 earthquake released more energy than the earthquake of 1946. The tsunamis force by this 1957 event caused less damage than the tsunami of 1946. This potential of destructive power of a tsunami forces Pacific Tsunami.

These pictures are in a series of three sequential photos show the arrival of a major wave at Laie Point on the Island of Oahu, Hawaii. Photograph Credit: Henry Helbush. Source: National Geophysical Data Center.

1996 PeruFebruary 21, 1996, at 12:51 p.m. GMT (7:51 a.m. local time), there was a largeEarthquake that struck approximately 130 Km off the northern coastal region of Peru (9.6S, 80.2W). The earthquake had a Harvard Mw estimate of 7.5 and USGS Mw estimate of 7.3. The earthquake generated a tsunami that reached the center of Peru on the city of Chimbote. The Effects of the tsunami were observed from Pascasmayo, in the department of La Liberated, to the Port of Callao near Lima. The straight line distance between these two locations is approximately 590 Km. The tsunami was recorded by mid-Pacific tide gages, 60 cm at Easter Island, and 25 cm at Hilo, Hawaii. The aftershock pattern ranged from 120 to 180 Km offshore near the Peru-Chile trench and appeared to parallel the Peruvian coastline.

The International Survey Team who gathered the data.

1960 Chilean TsunamiOn May 22, 1960, at 7:11 , an earthquake occurred off the coast of South Central Chile. There was a tsunami triggered by the earthquake, which had a surface-wave magnitude of 8.6, an epicenter of 39.5° S, 74.5° W, and a focaldepth of 33 km. The number of deaths caused by both the tsunami and the earthquake and approximately 490 to 2,290. The Damage cost was estimates well over a half billion dollars.

The inhabitants, feared the earthquake, they were in boats to escape the shaking. The trough of the tsunami arrived just 10 to 15 minutes after the earthquake, along more than 500 m of the coast. After the tsunami had gone by the Hawaiian Islands had damage costs that were approximately at $24 million and 61 people had lost here lives. Hilo, on the main island of Hawaii, was the hardest hit city in the islands. The tsunami arrived at Hilo 14.8 hrs after it was created off the coast of South Central Chile. The waves at Hilo was measured at 10.7 m.

An aerial view of the coast of Isla Chiloe, Chile, showing the tsunami damage.

1964 Prince William SoundOn March 28, 1964, at 03:28 GMT, an earthquake occurred in Prince William Sound of Alaska triggering a Pacific-wide tsunami. The earthquake had a surface-wave magnitude of 8.4, an epicenter of 61.1° N, 147.5° W, and a depth of 23 km.  The tsunami was responsible for taking more then 122 people and causing over $106 million in damage.

Whittier incurred $10 million in property damage. One of the waves, probably the same one that caused the major damage in Whittier, reached a height of 31.7 m above low tide They also caused great damage to the small boat harbor. The tsunami took the lives of thirteen people at Whittier, then a community of 70 people The greatest damages suffered by any location was Alaska. In Alaska 106 people lost their lives and  $84 million in damage.

The Tsunami left a 2 x 12 inch plank of wood through a truck tire at Whittier, Alaska. Whittier incurred $10 million dollars in property damage.

1975 HawaiiNovember 29, 1975, at 2:48 GMT, a tsunami was created by an earth quake off the shore of Hawaii. The tsunami had a magnitude of 7.2, an epicenter of 19.3° N, 155.0° W, and a focal depth of 8 km. At Halape, there was 32 campers. Out of the 32, 19 were injured and 2 died. It sounded like boulders falling, there was a second earthquake that woke the campers. They all ran to the coconut grove which was closer to the ocean. The campers were awaken by a second quake that sent large boulders down the cliff and the rest of the campers to fleed toward the sea. These campers had to go back to cliffs when the other campers at the coconut grove fleeing the rising ocean with there cries of a tsunami. The tsunamis first wave that alarmed the campers was only 1.5 m. The second wave, however, was 7.9 m carried campers into a ditch near the base of cliff where they remained until the end. There were two campers that died from this.

The largest recorded run-up was 14.3 m at Keauhou Landing, Hawaii Island. Also on the Island of Hawaii in the small bay of Punaluu the run-up reached 7.6 m.At Punaluu houses were swept off their foundations and properties were damaged.

What is the highest known tsunami?

The highest tsunami, with a reliably measurement on record occurred on July 9, 1958 in Lituya Bay, Alaska. This was caused by a landslide that fell into the bay. This unusual happening, caused by a wave to surge up the slope on the opposite side of the bay to a height of 518 m(1,700 ft). Scientists believe that bigger tsunamis happened a long time ago by asteroids, or large meteors, falling into the ocean. Two places their looking for evidence of these tsunamis are Hawaii and the coast on the Gulf of Mexico. The landslide came from the mountain(A) into the bay(B).

2004 Indian Ocean earthquake and tsunami

• The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, 26 December 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra–Andaman earthquake. The resulting tsunami was given various names, including the 2004 Indian Ocean tsunami, South Asian tsunami, Indonesian tsunami, the Christmas tsunami and the Boxing Day tsunami.

The earthquake was caused when the Indian Plate was subducted by the Burma Plate and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 ft) high. It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest-hit country, followed by Sri Lanka, India, and Thailand.With a magnitude of Mw 9.1–9.3, it is the third largest earthquake ever recorded on a seismograph. The earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 centimetre (0.4 inches)and triggered other earthquakes as far away as Alaska. Its epicentre was between Simeulueand mainland Indonesia.The plight of the affected people and countriesprompted a worldwide humanitarian response. In all, the worldwide community donated more than $14 billion (2004 US$) in humanitarian aid.

16 minutes after OT 104 minutes after OT

Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

26 Dec. 2004 Tsunami max. wave height and arrival time

Seismic Eruption software: http://www.geol.binghamton.edu/faculty/jones/ Indonesia area historical earthquakes files, download from:http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm

Seismic Eruption software: http://www.geol.binghamton.edu/faculty/jones/ Sumatra earthquake and aftershocks files, download from:http://web.ics.purdue.edu/~braile/edumod/tsunami/TsunamiFiles.htm

Propagation, Response and Warning Times for the M9.0 Sumatra EQ

122 minutes after OT

Indian OceanLittle communication fromBanda Aceh

Destruction in Pkuket

Tsunami hits Sri Lanka

NEICContinuing dialogue betweenUSGS scientists in Golden,Reston and Menlo Park

No confirmation via wireservices of tsunami in theIndian Ocean

Wire service reports of building collapse in BandaAceh

Web content is beingdeveloped and posted

Banda Aceh, Sumatra, before tsunami

Banda Aceh, Sumatra, after tsunami

Tsunami Warning

• As soon as an earthquake of magnitude >6.5 is located in the sea the alarm start.

• Using computer simulations and maps like the one in the following slide scientists forecast the time of arrival in different locations.

• The use of Buoy and tide gauges help to verify the effective presence of a tsunami, the alarm is given.

Tsunami Hazard Mitigation

• We can warn people of potential tsunamis from distant earthquakes. Warning of near source tsunamis is much more difficult.

• Prevention of tsunami catastrophes requires carefully planned use of low-lying areas.– This is not always possible, or affordable.

Effects on natureThe effect of nature can be quite devastating. But only along the coastline is where all the damage is. The waves can knock over trees, wash away beaches and floods lower regions.

A montage from Papua New Guinea.

Damage on the shore of Izmit Bay, Turkey.

Izmit shore, as seen from the sea.

There are three videos. The first one shows the effect on nature. The others show the effect on people.

Effect on Humanitarian , economic and environmental impact

A great deal of humanitarian aid was needed because of widespread damage of the infrastructure, shortages of food and water, and economic damage. Epidemics were of special concern due to the high population density and tropical climate of the affected areas. The main concern of humanitarian and government agencies was to provide sanitation facilities and fresh drinking water to contain the spread of diseases such as cholera, diphtheria, dysentery, typhoid and hepatitis A and B.There was also a great concern that the death toll could increase as disease and hunger spread. However, because of the initial quick response, this was minimized

Can We Do Better? Yes

•Improved sensor networks in hazards areas of the world (seismic, tide gauge, ocean buoys) and coordinated distribution and processing of data

•Better information content that can better assist emergency responders to assess the scope of the disaster

•Coordination and integration with national, regional and local emergency response agencies and civil authorities

•Education and training at national, regional and local levels of government and the general population

Protecting Yourself (Tsunami)

• Move to higher ground.

• Wait until authorities give the go ahead to return to low-lying regions.

• Watch for surges of water in rivers and streams near the coast.

• If you feel a strong earthquake, don’t wait for a formal warning.

What to do during a tsunami?

If you feel an earthquake that lasts 20 seconds or longer when you are on the coast; the Red cross advises you to;

Drop, cover, and hold on. You should first protect yourself from the earthquake.

When the shaking stops, gather your family members and evacuate quickly. Leave everything else behind. A tsunami may be coming within minutes. Move quickly to higher ground away from the coast.

Be careful to avoid downed power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock.

Tsunami velocity and amplitude equations

(These are plane layer [flat ocean bottom] equations)

1. Wave velocity controlled by water depth:

v = (g x d)1/2 where v is velocity, d is water depth and g is the acceleration of gravity = 9.8 m/s2; so, velocity decreases in shallower water.

2. Wave height (amplitude) increases (conservation of energy) in shallow water:

AS = AD x (VD/VS)1/2 where AS = amplitude in shallow water, AD = amplitude in deep water, VS = velocity in shallow water, and VD = velocity in deep water.

Geist, Titov and Synolakis, Tsunami: Wave of Change, Scientific American, January, 2006.

Wave Heights – Satellite observation versus calculated model – open ocean, deep water

~1600 km; ~2.2 hours of waves at 750 km/hr