Year of selection 2015
Institution Uppsala University
Climate change is responsible for many transformations taking place on earth, including, potentially, more earthquakes. Dr. Rebekka Steffen is a geoscientist studying the impact of melting ice sheets on seismic activity. As the load of ice decreases, it changes the stress present in the earth’s crust. These forces could activate formerly quiet seismic faults and generate powerful earthquakes. Researchers know that such glacially induced earthquakes occurred in the Nordic region 10,000 years ago. With climate change and shrinking ice sheets, similar activity is likely to increase around the world, but the phenomenon has been little studied. Dr. Steffen is, thus, taking on the question in Greenland, where increased interest in its natural resources could put infrastructure at risk of earthquakes. Should she find the potential for seismic activity in the oceanic crust here, both sides of the North Atlantic could be threatened by tsunamis, too.
The planet’s crust is more malleable than everyday experience leads us to believe. The weight of glaciers presses down on the Earth below and creates uplift of the area around them. When the ice melts, the surface slowly readjusts to its previous shape, the crust actually moving through viscous flow in the mantle underneath. Even when the ice disappears, removing that source of vertical pressure, residual horizontal stresses linger from the deformation of the crust. These forces are capable of reactivating formerly stable faults. The latter begin to move and, historically, have triggered earthquakes up to 8.0 in magnitude in northern Europe – equivalent to those seen along large plate boundaries, as in Japan and Indonesia.
Through a combination of techniques from the geosciences and computer modeling, Dr. Steffen aims to quantify the increased seismic hazard that could be created by Greenland’s melting ice. No existing model is sophisticated enough to handle this goal. So, building on her previous work, she will develop a new model capable of mapping out the subsurface forces at work in Greenland, in high-resolution and in three-dimensions. By creating such a tool, capable of representing realistic fault slip behavior, she will be able to identify areas of Greenland that may have experienced powerful earthquakes in the past as a result of lost ice mass, as well as areas that could be at risk today as the melting continues or even accelerates. If she finds that any faults off Greenland’s coast, beneath the ocean, are unstable, she will also assess the potential for tsunamis and the risk they would pose for the coasts of Europe and North America.
Because many regions previously covered in glaciers are stable, continental zones, only small or moderate earthquakes are typically expected there. If ice loss is capable of generating magnitude-8 quakes, however, it would mean the risk for Greenland has been significantly underestimated. Knowledge of this hazard will be important for industry players currently increasing offshore oil production and mineral extraction in the country with all the requisite infrastructure. The effects of a major earthquake plus tsunami would be felt by many more. Ice sheets around the world are currently melting and sea-level rise is clearly not the only reason to be concerned. Fortunately, Dr. Steffen’s model will be applicable to other regions, like Antarctica, making it possible to assess links between seismic activity there and the potential for unexpected tsunamis in South America, Southern Asia and Australia. Her work investigating the connections between climate change and powerful movements of the earth and oceans could aid in the prevention of coastal risks and the development of tsunami warning systems where today there are none.
Scientific title: Glacially Induced Earthquakes In Greenland
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