For almost half a century, geophysicists have studied active fault zones in an attempt to predict when and where the next major earthquake might strike. To find out how far we have come in this endeavour, watch this video with David Schwartz, an earthquake geologist with the US Geological Survey.

As Schwartz explains, geoscientists study active fault zones in an attempt to look for signs that an earthquake might be imminent. The difficulty, in his view, is that large earthquakes tend to originate several kilometres below the Earth's surface, and our planet's crust varies significantly with depth. "Being able to find one precursor, one thing that's common to this huge complexity, to give you a signal that something large is impending is very, very difficult," he says.

However, geophysicists continue to develop systems for monitoring fault zones. One approach Schwartz believes to be particularly promising is the idea of monitoring the Earth from space using the Global Positioning System (GPS). Seismologists could then study in real time how strain varies in rocks to identify particular locales where a slip could be about to occur. "There may be a time when you can turn on your TV at night and in addition to getting the weather report, you'll get the strain report," speculates Schwartz.

This interview was filmed in San Francisco at the 2011 Fall Meeting of the American Geophysical Union.