Because these faults are also intracontinental in nature, they too could be capable of large-magnitude events. Spotting faults from space John Everett, a geologist at Earth Satellite Corp., worked on the original Landsat data that Jacobi's team ultimately incorporated into their study. Everett said there is plenty of evidence to indicate that the East Coast has active faults. Because faults can go so long between major movements, Everett said, Jacobi's technique is a valuable to way to help spot potentially active faults. But the biggest problem is finding these things in the first place.
Landsat images show natural landforms and also shapes created by humans.
Once potential faults have been catalogued, geologists can go into the field and look for signs they still are active. A leaning tree, for example, can indicate that a fault is slipping quietly over time, possibly building stress that might give way in a sudden snap. Or, related rock outcroppings on two sides of a valley can be compared, showing height differences that reflect movement going back millions of years. There are many clues to look for, the most obvious being streams. Stressed vegetation blooms later in the spring and turns color earlier in the fall.