| At first glance, there doesn't seem like there could be | | | | Glacial melting has a less direct but just as unsettling |
| any connection between global warming and seismic | | | | additional impact on global seismic activity. The |
| activity. After all, why would the earth become less | | | | reliquified water released raises sea levels and |
| stable just because it's a little warmer? | | | | increases the weight on the ocean floor, unbalancing |
| Well, connected they are. The earth's crust is a lot | | | | tectonic forces deep below the surface. Underwater |
| more sensitive than you might think. There are well | | | | quakes and therefore tsunamis could thus become |
| documented cases of even the load of water in a | | | | more frequent. Though they get little attention, glacial |
| new dam triggering earthquakes in the local area. | | | | melting of the Antarctic ice is already causing |
| A number of geologists say glacial melting, in particular, | | | | earthquakes and underwater landslides. |
| will unleash pent-up pressures in the Earth's crust, | | | | Other hotspots at high risk of submarine earthslides - |
| causing extreme geological events such as | | | | similar to the one that set off the disastrous tsunami in |
| earthquakes, tsunamis and volcanic eruptions. | | | | Indonesia in 2004 - include seaward of the mouths of |
| Consider this: a cubic meter of ice weighs nearly a ton | | | | the Ganges, Nile and Amazon rivers, as well as much |
| and some glaciers are kilometers thick. This prodigious | | | | of the Atlantic and US coast (E. G. Nisbet, 2004.) |
| weight acts to suppress tectonic movements in the | | | | Even the shape of the Earth appears to have been |
| underlying crust, and plug cracks where volcanic | | | | significantly influenced by climate events due to |
| magma might otherwise escape to the surface. When | | | | changes in the mass of water stored in oceans, |
| the weight is removed through melting, the suppressed | | | | continents and atmosphere. Satellite data indicate the |
| strains and stresses of the underlying rock are free to | | | | bulge in Earth's gravity field at the equator is growing, |
| come to life. | | | | counteracting the long-term shrinking up to 1998 due to |
| As reported only this year, Harvard seismologist | | | | post-glacial rebound. |
| Göran Ekström has found a striking increase | | | | Current estimates of polar ice melting are too small to |
| in the frequency of glacial quakes, particularly in | | | | explain the recent changes in the gravity field. |
| Greenland, but also in Alaska and Antarctica. | | | | Scientists postulate that global warming-induced |
| Greenland quakes have risen from 6 to 15 a year | | | | redistribution of existing water mass is possibly behind |
| between 1993 and 2002, to 30 in 2003, 23 in 2004 and | | | | the phenomenon. However, the specific cause still |
| 32 in the first 10 months of 2005, closely matching the | | | | remains a mystery. |
| rise in Greenland's temperatures over the same period. | | | | Dramatic climate shifts of the past have also been |
| Their source was traced to surges and slips within ice | | | | associated with spectacular seismic activity. During the |
| sheets, where rapid melting is causing water to collect | | | | late glacial and early Holocene periods when climate |
| under glaciers, making them glide faster into the sea, | | | | was see-sawing from one extreme to another in the |
| triggering quakes. | | | | interval known as the Younger Dryas, submarine |
| Similarly, retreating glaciers in southern Alaska are likely | | | | landslips were widespread. For example, 8,200 years |
| to open the way for future earthquake activity. | | | | ago an enormous slip in the Norwegian Sea involving |
| Accelerated melting of glacial ice decreases the load | | | | over 3000 cubic kilometers of material set off a |
| on the Earth's crust, thereby decreasing the pressure | | | | massive tsunami more than 20 meters high. At about |
| holding volcanic conduits closed. Already, we are | | | | the same time mega-earthquakes ruptured the crust |
| seeing evidence of new volcanic activity in Antarctica. | | | | and lifted Scandinavia's mountain backbone by 5 to 15 |
| A new, previously unknown volcano has appeared on | | | | meters. Could it happen again? |
| the sea bottom in waters off the Antarctic Peninsula, in | | | | The science suggests that as redistribution of the |
| an area with no previous record of volcanic activity. | | | | Earth's mass induced by global warming disturbs the |
| Investigations into a large area of surface slumping on | | | | relative equilibrium of its crust, monumental forces in |
| the West Antarctic Ice Sheet revealed a huge | | | | the form of increasing earthquakes, tsunamis and |
| accumulation of water underneath that has now been | | | | volcanic activity could be unleashed. And the forecasts |
| shown to be due to an active volcano erupting under | | | | from some quarters are dramatic - - not only will the |
| the sheet. | | | | earth shake, it will spit fire (Bueckert, 2006). |