Tsunami - Natural Disasters :: Central Kings Rural High School

Transcript Tsunami - Natural Disasters :: Central Kings Rural High School

Tsunamis

How bad are they?

By Travis Jordan Reid Best

Suddenly I heard a shout, ‘Big wave!’ The streetlights around us exploded almost in the same instant. I looked up and saw a locally well known fishing boat coming up over the Wailoa Bridge

" --

Susan Maeda Veriato on the 1960 tsunami in Hilo, as told to her son Travis

PTM Archive Photo: Yasuki Arakaki collection; Photographer: Cecilio Licos

What is a tsunami?

Beginning

The word is Japanese and means "harbor wave,”because of the effect on the low coastal areas. A Tsunami is a giant, or series of big waves caused by an immediate vertical disturbance that displaces the water from its normal position. This causes the water mass to try to regain normality by pushing away the displaced water. "The main factor which determines the initial size of a tsunami is the amount of vertical sea floor deformation" (WACTC). 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.

Middle

When a tsunami crosses the ocean its length (from crest to crest) can be 100 miles or more, and its trough won’t be any higher than two feet. A tsunami travels at speeds of 600 miles per hour in the deepest ocean. But once it reaches the shoaling water of the coastline its speed decreases, and the wave becomes increasingly higher. It is in the shallow waters that waves can be 100 feet high.

Tsunamis are not created from the wind.

Wind-created waves have a period of five to twenty seconds, and about 100 to 200 meters wavelengths. While tsunamis have periods that range from ten minutes to two hours and 300 mile long wavelengths.

End

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.

Art work

Great Wave off the Coast of Kanagawa,

by Hokusai, a Japanese artist. This piece of art work is misleading Because tsunami are not always huge breaking waves as depicted in the print.

Most Destructive recent Tsunamis

1946

1952

1957

1960

1964

1996

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 Aleutian

April 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 Kamchatka

On 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 Aleutian

March 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.

1960 Chilean Tsunami

On 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 focal depth 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 Sound

On 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 Hawaii

November 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.

1996 Peru

February 21, 1996, at 12:51 p.m. GMT (7:51 a.m. local time), there was a large Earthquake 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.

Which is worst? Regional or local tsunamis?

Regional tsunami are very destructive but local tsunamis also cause significant damage. Local tsunamis are created by landslides, which are started by earthquakes. At the Valdez Inlet a giant landslide started by the earthquake created a tsunami that had a run-up of 67.0 m at the inlet. In areas where local tsunamis are created by landslides, nearby cities are not given any warning of the oncoming waves.

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).

The American Red Cross

The American red crosses guild to help you prepare, get through, and survive a tsunami.

How to prepare for a tsunami?

Avoid building or living in buildings within several hundred feet of the coastline.

These areas are more likely to experience damage from tsunamis, strong winds, or coastal storms.

Make a list of items to bring inside in the event of a tsunami.

A list will help you remember anything that can be swept away by tsunami waters.

Elevate coastal homes.

Most tsunami waves are less than 10 feet. Elevating your house will help reduce damage to your property from most tsunamis.

Follow flood preparedness precautions.

Tsunamis are large amounts of water that crash onto the coastline, creating floods.

Have an engineer check your home and advise about ways to make it more resistant to tsunami water.

There may be ways to divert waves away from your property. Improperly built walls could make your situation worse. Consult with a professional for advice.

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.

What to do after a tsunami?

Skip

Continue listening to a NOAA Weather Radio, Coast Guard emergency frequency station, or other reliable source for emergency information.

The tsunami may have damaged roads, bridges, or other places that may be unsafe.

Help injured or trapped persons. Give first aid where appropriate.

Call for help. Do not move seriously injured persons unless they are in immediate danger of further injury.

Help a neighbor who may require special assistance--infants, elderly people, and people with disabilities.

Elderly people and people with disabilities may require additional assistance. People who care for them or who have large families may need additional assistance in emergency situations.

Use the telephone only for emergency calls.

Telephone lines are frequently overwhelmed in disaster situations. They need to be clear for emergency calls to get through.

Stay out of the building if waters remain around it.

Tsunami waters, like flood waters, can undermine foundations, causing buildings to sink, floors to crack, or walls to collapse.

When re-entering buildings or homes, use extreme caution.

Tsunami-driven flood waters may have damaged buildings where you least expect it. Carefully watch every step you take.

Wear sturdy shoes.

The most common injury following a disaster is cut feet.

Use battery-powered lanterns or flashlights when examining buildings.

Battery-powered lighting is the safest and easiest, preventing fire hazard for the user, occupants, and building.

Examine walls, floors, doors, staircases, and windows to make sure that the building is not in danger of collapsing. Inspect foundations for cracks or other damage.

building uninhabitable.

Cracks and damage to a foundation can render a next

Look for fire hazards.

There may be broken or leaking gas lines, flooded electrical circuits, or submerged furnaces or electrical appliances. Flammable or explosive materials may come from upstream. Fire is the most frequent hazard following floods.

Check for gas leaks.

If you smell gas or hear a blowing or hissing noise, open a window and quickly leave the building. Turn off the gas using the outside main valve if you can, and call the gas company from a neighbor's home. If you turn off the gas for any reason, it must be turned back on by a professional.

Look for electrical system damage.

If you see sparks or broken or frayed wires, or if you smell burning insulation, turn off the electricity at the main fuse box or circuit breaker. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice. Electrical equipment should be checked and dried before being returned to service.

Check for sewage and water line damage.

If you suspect sewage lines are damaged, avoid using the toilets and call a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap. You can obtain safe water from undamaged water heaters or by melting ice cubes.

Use tap water if local health officials advise it is safe.

Watch out for animals, especially poisonous snakes, that may have come into buildings with the water. Use a stick to poke through debris.

Tsunami flood waters flush snakes and animals out of their homes.

Watch for loose plaster, drywall, and ceilings that could fall.

Take pictures of the damage, both of the building and its contents, for insurance claims.

Open the windows and doors to help dry the building.

Shovel mud while it is still moist to give walls and floors an opportunity to dry.

Check food supplies.

Any food that has come in contact with flood waters may be contaminated and should be thrown out.

Help

There is no real place for the people to go after a tsunami hit. This is because mostly everything along the coast is destroyed, costing millions of dollars of damage. The people can go farther in shore for help because the tsunami doesn’t go far in shore.There is no real aid from the government to help them, but there is the red cross that helps anyone after a disaster hits. The disaster usually destroys everything in it’s path. But the red cross is always there to help.

Effects on people

On July 12. 1993, a powerful earthquake west of Hokkaido in the Sea of Japan unleashed a tsunami that devastated nearby Okushiri Island. The video you will see here shows Aonae Cape, a small peninsula that points south off of Okushiri. The peninsula was completely overtopped by the giant wave, to heights of over 10 m. (the largest recorded wave run-up on the island was nearly 30 m!) In the image above, the wave approached from the left and swept over the land. Structures remaining after the wave attack were destroyed by the fires that engulfed the area due to broken gas lines and toppled fuel containers.

Effects on nature

The 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.

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

A montage from Papua New Guinea.

Damage on the shore of Izmit Bay, Turkey.

Izmit shore, as seen from the sea.