It can be seen from the air and explored up close. Then there are existing faults that are out of sight, like the one that shook Japan in March.
"It was a remarkable event. It produced one of the largest tsunamis that has ever been recorded and the reason for that had to do with the peculiarities of the earthquake faulting off shore," said Thomas Jordan, director of the Southern California Earthquake Center.
Offshore faults are not as well studied since they are under water, but they are just as powerful.
"We have critical facilities, such as nuclear power plants. We want to make sure we understand the faults and the size of earthquakes that might occur on the coast line," Jordan said.
The San Onofre nuclear power plant was built to withstand a 7.0-magnitude earthquake and 25-foot tsunami. Its construction was based on earthquake research available at the time.
While scientists continue to learn about the characteristics of land and offshore faults, another science is emerging to help develop an early warning system based on that research.
Scientists are trying to determine if ground motion can be detected by using a GPS system to track earthquakes.
"If an earthquake occurs they'll know within a very short time period the magnitude of the earthquake and about how long it will take to get to a certain location so they can get a warning out to the people," said Hillary Tahtinen, who was at a conference for seismologists Monday.
This past March, a high-frequency radar in California detected the tsunami in Japan, which led to warning along the state's coast line.