Earthquakes cause sea level to rise faster than climate change: Aussie study

Professor Shin-Chan Han from the University of Newcastle discovered that sea levels in American Samoa rose at five times the global average due to land subsidence, a sinking effect in the earth's crust triggered by the 2009 Samoa-Tongan earthquakes.

"This could be even more dangerous to the region than the impact of climate change," Han said.

"The predicted sea level rise from land subsidence in American Samoa is just as much, if not more, than the Intergovernmental Panel on Climate Change projected a rise in the Samoan Islands due to climate change under the highest CO2 emission scenario."

Using images and other data from space, Han showed that in the eight years following the earthquake, the land subsided in American Samoa at a rate of 16 mm per year, compared with 8-10 mm per year in Samoa.

Han called for governments to urgently reassess their sea level predictions for countries affected by large earthquakes, with those over an eight in magnitude having the potential to radically deform the earth's crust.

In other countries like Japan and New Zealand, Han predicted that major earthquakes may actually cause the land to rise, although he said further investigation is needed.

"Government agencies must take into account land subsidence in earthquake-affected regions," Han said.

"Tectonic movements can greatly influence the rate that sea levels rise, and should be considered in addition to climate-induced changes."