Space station aims to spot seismic shocks
Radiation study could spur plans to monitor earthquakes from orbit.
An experiment aboard the International Space Station will check the theory that imminent earthquakes can be spotted from space.
Researchers hope that tracking changes in the radiation belts that blanket the globe will give them early warning of tremors hundreds of kilometres below. If successful, the work could help pave the way for a system of satellites that watch for earthquakes.
Seismologists know that the rumblings that precede an earthquake cause disturbances across a wide range of frequencies that can be picked up by radio antennae. These disruptions are thought to result from the opening of tiny cracks in the rocks as they begin to deform.
Monitoring these effects on the ground would require a huge, global network of antennae. Fortunately our planet has a natural version of such a net: bands of charged particles trapped in Earth's magnetic field, called Van Allen belts. These belts are best known for shielding the atmosphere from cosmic radiation.
Electromagnetic disturbances may be detectable in the Van Allen belts before an earthquake occurs, says Roberto Battiston of the University of Perugia, Italy, a coordinator of the study, which is called Lazio-Sirad. But, he adds, no one has yet been able to show that the effect can be spotted within the useful time frame of a few hours before an earthquake.
The International Space Station, cruising some 370 kilometres above Earth, grazes the lowest Van Allen belts at certain points in its orbit, providing a useful vantage point for observation.
The Lazio-Sirad experiment will monitor the number and direction of charged particles in these belts for at least one week, and possibly for up to six months. They will then try to correlate variations in this particle flux with natural events. Slow variations are expected to be caused by solar flares, and rapid changes are expected in response to seismic activity, Battiston explains.
The project began as a fresh crew arrived at the International Space Station on 15 April, including astronaut Roberto Vittori, who will oversee the experiment.
If the theory proves to be true, then our planet's rumblings could one day be monitored from space, Battiston suggests. "This is the hope and dream, but first we have to check that what has been hinted at is real. So far, evidence is still scarce."