It appears that two fault segments may have broken 30 seconds apart, producing the very large shocks.

Any large and longstanding gap is therefore considered to be the fault segment most likely to suffer future earthquakes.

The fault segment is one of those known as a seismic gap, a place where little significant earthquake activity has occurred relative to nearby stretches.

The dream we have is to use these methods to learn how fast each fault segment is moving.

Globally, the quake has also told us that it's possible for a relatively small fault segment to spawn a giant earthquake.

Other fault segments seem to be made of weaker rocks, he said, so that the rocks break more often, generating smaller earthquakes.

Ultimately, each fault segment deemed dangerous to people and property will have to be independently monitored.

"If an earthquake does not happen along that fault segment after a year or so, the danger would be less."

The 2000 Sumatra earthquake took place at the southeastern end of the fault segment that ruptured during the 1833.

It takes its name from the Hope River, which runs along one of the central fault segments.