The project, known as the San Andreas Fault Observatory at Depth (SAFOD), is part of the US National Science Foundation’s $200 million EarthScope survey of North America. EarthScope researchers will install seismometers, strain meters and GPS positioning devices at hundreds of sites across the continent. But SAFOD will take that research to a whole new level.

By drilling directly into the fault, the team will be able to observe the chemistry and physics of what happens before, during and after quakes as never before. SAFOD should reveal what drives the engine of earthquakes, what keeps them going and why they stop.

Many of the questions about the San Andreas fault apply to fault lines elsewhere, including the one that wreaked havoc around the Indian Ocean at the end of last year. “We are asking the same questions about the materials, fluid pressure, how earthquakes start and what stops them,” Zoback says. The results from SAFOD will help to refine the way scientists model earthquakes, and could even help determine how precisely they will be able to predict a quake’s location, timing and size.

The seeds of SAFOD were sown by earthquake experts in the 1980s, when a report by the US National Resource Council argued that researchers would need to dig to the very heart of earthquake zones if they were to unravel the big questions. Yet despite this huge potential pay-off, funding agencies refused to open their pockets until a few years ago.

The three geophysicists and their colleagues were not idle while they waited for the cash. In the 1990s, they pinpointed an ideal site, an interesting section of the San Andreas near the small town of Parkfield, California, which is hit every few years by small quakes. Using data from seismometers scattered across the surrounding landscape, they traced nearly all of those quakes back to a single origin: our 100-metre-square patch of fault some 3 kilometres below the surface.

More here.