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