The Earth is a living and changing place. Its surface is broken up into enormous tectonic plates, drifting and shifting over the globe. As the tsunami disaster on 26th December last year showed, movements between these plates can have devastating consequences, both for nature and human populations.
“Our planet can be friendly but it can also be vicious,” noted a European Commission representative as he introduced the lunchtime speaker Patrice Christmann, secretary-general of EuroGeoSurveys. “Technology can do little to prevent these natural events from happening, but space technology – as illustrated in the expo – can help mitigate the impacts,” he added.
Christmann gave a thorough account of the dawning of geological understanding, from confirmation of German geologist Alfred Wegener’s theory, early last century, that one giant continent broke up and drifted around the globe many millions of years ago, to scientists’ new interpretation of Noah’s Ark as a seismic-triggered flood.
In his presentation, called ‘Our living planet: geological hazards and disaster prevention’, we learned that geologists focus mostly on earthquakes and volcanoes, but they also keep a close eye on flooding (rising water tables), upward and downward ground movement (uplift and subsidence under, for example, cities), swelling and shrinking soils (the problem of building on clay), and natural emissions of gases (radon) and heavy metal poisons (arsenic) which threaten health.
Counting the costs
Natural disasters cost the world economy €48.4 billion in 2003, according to one of the interactive multimedia displays at the ESW. And, to Christmann, the most violent category of hazard is earthquakes. The UN Environment Programme calculated that, between 1975 and 2000, some 465 000 people were killed worldwide by these seismic tremors. Each year, there are between 12 000 and 14 000 of them recorded, often triggering other hazards, such as tsunamis, landslides, rockfalls, flooding, and damage to infrastructure like dams and power stations.
One member of the audience asked the speaker why early-warning systems for earthquakes are not as accurate as those for hurricanes. Christmann said science cannot really predict them but it can mitigate their impact, using historical data. By looking at past events and their intensity, it can model and map the risk zones and help decision-makers prepare for the inevitable devastation – having emergency services in place, for instance.
“But this requires a coordinated human, material and financial effort,” he said. If Spot satellites (which have been monitoring the Earth from above since the 1970s), or land-based monitoring, pick up a major tremor near, for example, a nuclear plant, in split seconds authorities must be alerted to prevent a nuclear disaster. Timing is also important for limiting the death toll.
“In disaster situations, the first 24 hours are considered the ‘golden hours’ for saving lives – after that there is much less chance,” stressed Christmann. This applies to any natural disaster. However, in the case of volcanoes, the authorities tend to be better prepared so the loss of lives can often be prevented.
The world’s active volcanoes are known and, for the most part, are well monitored using a combination of ground- and space-based technologies, from space-based global positioning systems (GPS) to tiltmeters planted on the sides of these volatile mountains. Minute changes in volcanic activity are recorded, and predictions – using historical data and benchmarks – are made regarding the likelihood of an eruption. If the risk is high, people can be moved before the explosion, reducing potential loss of lives (i.e. only 26 000 people were killed by volcanic activity between 1975 and 2000) but damage to property is less avoidable.
|“Our planet is not a cold, static, lifeless place.” Patrice Christmann|
“Our planet is not a cold, static, lifeless place,” explained Christmann. “It is more like an egg, a living evolving system.” But this makes it fragile and unpredictable. “Nature can be a source of a range of hazards – some rare and impressive, some more common in certain locations, others not noticeable by direct observation,” he said. Most have one thing in common – they are not preventable. The main task, in these cases, is to minimise the loss of life and property, and the integration of Earth and space technology and know-how is a major tool in the geologist’s kitbag.