From New Zealand to Newcastle, secrets lie beneath our feet

As the clean-up continues after the Christchurch earthquake, it is worth reminding ourselves how recently we gained any understanding of the earth's interior. The idea that the planet's crust is split into tectonic plates was proposed early in the 20th century, but derided for decades. Only in the early 1960s, after cold war submarine tracking technology was used to map the ocean floor, did scientists accept the idea that we live on a flotilla of writhing, sliding plates.

To the east of North Island in New Zealand, for instance, the Pacific plate is moving into the region of the Australian plate: as the two meet, one slides under the other in a process known as subduction. Another fault runs along South Island, where two plates are sliding parallel to one another. The resulting seismological and volcanic activity has given the region a blood-curdling name: the Pacific Ring of Fire. There's a price to pay for New Zealand's dramatic scenery.

It would be foolish to think that we could ever take control of such great forces, but there is hope that scientists can mitigate disaster.
A project that drilled three kilometres into the San Andreas Fault, for example, has enabled researchers to understand the geology better and instal instruments that will form an earthquake early warning system.

Just outside Naples, scientists from 18 countries are hoping to do something even more daring - they want to drill into a volcano. Campi Flegrei dwarfs nearby Vesuvius, and could cause global catastrophe if it erupts. The scientists plan to make seven holes in the caldera and place instruments inside them. This, they hope, will help to identify what causes an eruption - and perhaps provide warning of impending volcanic activity. Not everyone is convinced. The local mayor has put the project on hold until he is satisfied that the drilling won't trigger an eruption and bury large parts of Europe under a thick layer of ash.

Such caution might be no bad thing: our knowledge of what lies beneath our feet is still sketchy. In 2005, a drilling project in Hawaii, set up to tap geothermal energy reserves, had to come to a halt when it hit molten rock at far shallower depths than expected. Magma leaked into the borehole and blocked it up.

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A similar thing happened in Iceland in June 2009, with a little more drama. The Iceland Deep Drilling Project had embarked on sinking a 4.5-kilometre borehole, but hit magma at just over two kilometres. Heat vaporised the drilling fluid, caused an explosion and halted the project. It's not all bad news: the discovery of shallow magma reserves opens up an even better heat source.

In distinctly unvolcanic Britain, such goings-on might seem a bit exotic and exciting - unless you live in Newcastle, that is. The drilling that started next door to St James' Park late last month will tap a source of renewable geothermal energy two kilometres beneath the city centre. The aim is to pump water down the hole, where it will reach temperatures of roughly 80° Celsius. On its return to the surface, it will be used to heat a number of buildings.

The first hot water is due out in June. It should all go smoothly, but the people of Tyneside would do well to keep an ear out for deep rumblings, or sounds of something letting off steam. There's a chance that it won't be just the mid-season frustrations of the Toon Army.

Tags:Science