Major earthquakes can cause sea levels to rise at a dramatically faster rate than climate change, making them a more significant concern to some Pacific Island nations. This is revealed in an Australian study in which it was 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.
Using images and other data from space, Professor Shin-Chan Han from the University of Newcastle 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. He further added that tectonic movements can greatly influence the rate that sea levels rise, and should be considered in addition to climate-induced changes.