Recent climate change research predicts that we will see more earthquakes, volcanoes and tsunamis as global warming unfolds. What's the connection between global warming and seismic activity? This report reviews the latest evidence.
At first glance, there doesn’t seem like there could be any connection between global warming and seismic activity. After all, why would the earth become less stable just because it’s a little warmer?
Well, connected they are. The earth’s crust is a lot more sensitive than you might think. There are well documented cases of even the load of water in a new dam triggering earthquakes in the local area.
A number of geologists say glacial melting, in particular, will unleash pent-up pressures in the Earth's crust, causing extreme geological events such as earthquakes, tsunamis and volcanic eruptions.
Consider this: a cubic meter of ice weighs nearly a ton and some glaciers are kilometers thick. This prodigious weight acts to suppress tectonic movements in the underlying crust, and plug cracks where volcanic magma might otherwise escape to the surface. When the weight is removed through melting, the suppressed strains and stresses of the underlying rock are free to come to life.
As reported only this year, Harvard seismologist Göran Ekström has found a striking increase in the frequency of glacial quakes, particularly in Greenland, but also in Alaska and Antarctica.
Greenland quakes have risen from 6 to 15 a year between 1993 and 2002, to 30 in 2003, 23 in 2004 and 32 in the first 10 months of 2005, closely matching the rise in Greenland's temperatures over the same period. Their source was traced to surges and slips within ice sheets, where rapid melting is causing water to collect under glaciers, making them glide faster into the sea, triggering quakes.
Similarly, retreating glaciers in southern Alaska are likely to open the way for future earthquake activity.
Already, as the ice melts, we are seeing evidence of new volcanic activity in Antarctica. A new, previously unknown volcano has appeared on the sea bottom in waters off the Antarctic Peninsula, in an area with no previous record of volcanic activity. Investigations into a large area of surface slumping on the West Antarctic Ice Sheet revealed a huge accumulation of water underneath that has now been shown to be due to an active volcano erupting under the sheet.
Glacial melting has a less direct but just as unsettling additional impact on global seismic activity. The reliquified water released raises sea levels and increases the weight on the ocean floor, unbalancing tectonic forces deep below the surface. Underwater quakes and therefore tsunamis could thus become more frequent. Though they get little attention, glacial melting of the Antarctic ice is already causing earthquakes and underwater landslides.
Dramatic climate shifts of the past have also been associated with spectacular seismic activity. During the late glacial and early Holocene periods when climate was see-sawing from one extreme to another in the interval known as the Younger Dryas, submarine landslips were widespread. For example, 8,200 years ago an enormous slip in the Norwegian Sea involving over 3000 cubic kilometers of material set off a massive tsunami more than 20 meters high. At about the same time mega-earthquakes ruptured the crust and lifted Scandinavia’s mountain backbone by 5 to 15 meters.
In accord with scientific predictions it is entirely possible that, as redistribution of the Earth’s mass - induced by global warming - disturbs the relative equilibrium of its crust, monumental forces in the form of increasing earthquakes, tsunamis and volcanic activity will be unleashed. And the forecasts from some quarters are dramatic - – not only will the earth shake, it will spit fire.
Well, connected they are. The earth’s crust is a lot more sensitive than you might think. There are well documented cases of even the load of water in a new dam triggering earthquakes in the local area.
A number of geologists say glacial melting, in particular, will unleash pent-up pressures in the Earth's crust, causing extreme geological events such as earthquakes, tsunamis and volcanic eruptions.
Consider this: a cubic meter of ice weighs nearly a ton and some glaciers are kilometers thick. This prodigious weight acts to suppress tectonic movements in the underlying crust, and plug cracks where volcanic magma might otherwise escape to the surface. When the weight is removed through melting, the suppressed strains and stresses of the underlying rock are free to come to life.
As reported only this year, Harvard seismologist Göran Ekström has found a striking increase in the frequency of glacial quakes, particularly in Greenland, but also in Alaska and Antarctica.
Greenland quakes have risen from 6 to 15 a year between 1993 and 2002, to 30 in 2003, 23 in 2004 and 32 in the first 10 months of 2005, closely matching the rise in Greenland's temperatures over the same period. Their source was traced to surges and slips within ice sheets, where rapid melting is causing water to collect under glaciers, making them glide faster into the sea, triggering quakes.
Similarly, retreating glaciers in southern Alaska are likely to open the way for future earthquake activity.
Already, as the ice melts, we are seeing evidence of new volcanic activity in Antarctica. A new, previously unknown volcano has appeared on the sea bottom in waters off the Antarctic Peninsula, in an area with no previous record of volcanic activity. Investigations into a large area of surface slumping on the West Antarctic Ice Sheet revealed a huge accumulation of water underneath that has now been shown to be due to an active volcano erupting under the sheet.
Glacial melting has a less direct but just as unsettling additional impact on global seismic activity. The reliquified water released raises sea levels and increases the weight on the ocean floor, unbalancing tectonic forces deep below the surface. Underwater quakes and therefore tsunamis could thus become more frequent. Though they get little attention, glacial melting of the Antarctic ice is already causing earthquakes and underwater landslides.
Dramatic climate shifts of the past have also been associated with spectacular seismic activity. During the late glacial and early Holocene periods when climate was see-sawing from one extreme to another in the interval known as the Younger Dryas, submarine landslips were widespread. For example, 8,200 years ago an enormous slip in the Norwegian Sea involving over 3000 cubic kilometers of material set off a massive tsunami more than 20 meters high. At about the same time mega-earthquakes ruptured the crust and lifted Scandinavia’s mountain backbone by 5 to 15 meters.
In accord with scientific predictions it is entirely possible that, as redistribution of the Earth’s mass - induced by global warming - disturbs the relative equilibrium of its crust, monumental forces in the form of increasing earthquakes, tsunamis and volcanic activity will be unleashed. And the forecasts from some quarters are dramatic - – not only will the earth shake, it will spit fire.
 | By Dr Margaret Lillian Published: 11/26/2006 |
