Tsunami in Pacific - expert comment

Dr Jonathan Dale, lecturer in physical geography and coastal scientist at the Department for Geography and Environmental Science, University of Reading, said:

"The tsunami is a major concern due to both the location of earthquake and the magnitude. A considerable amount of water will have been displaced by the movement during the earthquake, with the resulting wave then able to spread across the entire Pacific Ocean, which is the world's largest and deepest ocean. As a result, a large geographical area is considered to be a risk.

"Hawaii’s location in the middle of the Pacific Ocean means it is extremely vulnerable to the tsunami waves caused by this earthquake, but there are also densely populated areas on both sides of the Pacific Ocean that could be at affected. These include parts of Japan, and America’s west coast.

"Given that the earthquake occurred on a major tectonic plate boundary, there is always a probability that an earthquake could occur. What is noteworthy with this event is the magnitude of the earthquake. Whilst the magnitude of 8.8 is lower than both earthquakes that caused the Boxing Day tsunami in 2004, and the tsunami which resulted in the Fukushima nuclear accident in Japan in 2011, it is still likely the joint sixth largest earthquake on record."

Dr Alison MacLeod, associate professor and researcher in abrupt past climatic and environmental change, in the Department of Geography and Environmental Science at the University of Reading, said:

"From a climate perspective, we are projected to experience rising sea levels in the future, as a result of both warming of the oceans, known as thermal expansion, and contribution from melting ice in the polar regions.

"Sea level rise will have an impact generally, particularly for communities in low-lying coastal areas, but when considering the impact of a tsunami on top of higher sea levels, there is the potential for an enhanced impact on people, infrastructure and the wider environment. Higher sea levels cause tsunami to have higher run-up heights and potentially higher energy waves.

"Wave height in a tsunami is partly controlled by the intensity and type of event that triggered it, and the shape of the coastline. Trying to fit a large amount of water into a shallow or narrow bay will increase the height of the wave compared to that experienced in areas with deeper coastal waters, due to the way the water is focused.

"The effectiveness of the integrated early warning systems and maintaining education about the potential impacts of these events across the Pacific will play a significant role in protecting populations, and may influence planning and how infrastructure projects are implemented. In the future, some communities will be able to adapt better than others, as some island communities for example lack the resources and the alternatives to living beside the coast."

Dr Jess Neumann, associate professor of hydrology at the University of Reading, said:

"Early warning systems so far appear to have been effective allowing for timely evacuations. However, unusual waves and potentially dangerous coastal activity is expected to continue for many hours even once the main tsunami waves pass. People are urged to take the risk to life seriously, remain vigilant, follow all evacuation orders and stay away from coastal areas.

"The 8.8 magnitude earthquake that hit off Russia’s Kamchatka Peninsula triggered tsunami warnings across the Pacific coast. Tsunami heights of up to 3m above sea level were expected across coastal areas including Japan, Hawaii, Chile, Ecuador and the Pacific Islands and with heights of around 1m anticipated in areas such as Australia, New Zealand, Taiwan and Mexico.

"Tsunami waves are not individual events, but can cause a series of waves that can surge inland along coastal areas and wrap around islands. Tsunami waves are not like normal surface waves, they are movements through the whole water column that travel over long distances. Even seemingly small waves carry tremendous force and can cause substantial damage and destruction."