There would be significant damage, and small buildings would be destroyed, but bigger structures would be spared. The structures that have been demolished were all of light-frame construction. Heavy steel, concrete, and masonry are still present. Skyscrapers, in particular, since their foundations are extremely sturdy. A tsunami can destroy entire towns, but it cannot break a building's skeleton.
Tsunamis can reach high levels of power and be very dangerous. They can also cause very serious damage even if they aren't particularly large. Recent tsunamis have caused huge amounts of death and destruction due to their magnitude and how far they travel. Smaller tsunamis have also occurred throughout history that we know about today only because some remains or evidence is still present at the ocean floor.
The 2004 Indian Ocean earthquake and subsequent tsunami was one of the largest ever recorded in human history. It killed approximately 230,000 people in 14 countries. The earthquake itself was estimated to have had a magnitude of 9.1. The resulting tsunami swept away whole villages and killed everyone in its path.
In Japan, more than 20,000 people died in 1990 when another tsunami struck the country. In addition, hundreds of people are reported to have died in Indonesia and Australia as result of recent earthquakes.
Tsunamis are violent waves in the water caused by an underwater landslide or other mass movement.
Consider other tsunami-affected places. The massive structures are still standing. Take a look at the photographs of Aceh, Indonesia, Japan, and other countries they've visited. None of them seem to have suffered major damage.
The reason is that tsunamis are not deadly unless you're in their way. Their force is used primarily for disruption, rather than destruction. When a tsunami hits land, it moves at high speed and can lift large objects with little effort. But when the wave reaches solid ground, its energy is dissipated and it slows to sea level pace.
For this reason, large buildings have time to get out of the way. They can be swept away from their foundations or blown over, but they aren't damaged by being moved. Smaller objects such as cars, boats, and furniture are damaged or destroyed when they come into contact with hard surfaces such as rocks or debris fields.
This was demonstrated in 2004 when a tsunami caused by an earthquake in Southeast Asia reached Australia. The image below shows the damage done to buildings in Ocean Shores, Washington. You can see many large trees that were once located near the shoreline, but now stand far inland. This shows that the ocean has taken things away from their normal locations; however, there does not appear to be much damage to homes here.
In total, around 122,000 buildings were entirely destroyed, approximately 283,000 were severely damaged, and another 748,000 were moderately damaged.
The number of completely destroyed buildings is estimated to be between 120,000 and 150,000, while the estimate for severely damaged buildings is between 270,000 and 320,000. The total number of damaged buildings is thus estimated to be between 390,000 and 470,000.
Almost all of the destroyed or severely damaged buildings are estimated to be made of wood, with some concrete and metal buildings also reported lost.
The number of people killed by the tsunami is estimated to be between 18,500 and 20,500, with a further 50,000 people injured.
Nearly all of the deaths occurred in Indonesia, with around 1,800 people also reported dead in Thailand.
The economic cost of the tsunami is estimated to be around US$50 billion (2011 dollars).
It is calculated that the price tag would be around $7 million per death.
This makes the Indonesian tsunami one of the most expensive disasters in history.
Skyscrapers are just too large to transport and too expensive to deconstruct and reassemble. It would be less expensive to demolish a skyscraper and rebuild it than to try to relocate it.
Relocating a tall building is difficult because the weight of the building causes soil under it to collapse, which can lead to other problems for the surrounding area. The building itself may have to be stabilized before it can be moved, which increases the cost of relocation.
There have been attempts over the years to move buildings, but none have been successful. A 12-story brick building was dismantled in New York City in 1849 and its parts were sold for reuse or demolition. This is the only known attempt at a major building relocation in North America.
A 23-story brick building on Chestnut Street in Philadelphia was demolished by dynamiting it down block by block in 1869.
In 1895, the Hetzel Building in Detroit was torn down engine house-style and rebuilt several blocks away. The new building was almost as tall as the old one had been.
The next year, the Weaver Brothers' Store in Evansville, Indiana was pulled down brick by brick and rebuilt about a quarter mile away. This building was much shorter than the Hetzel Building, only seven stories high.