Most scientists assumed that a steady creeping movement in the San Andreas Fault released a safe amount of energy, but a new study debunks that.
What Did Researchers Discover About The San Andreas Fault?
New research found that tiny movements along the central part of the San Andreas Fault, which are called slow earthquakes, could prompt bigger earthquakes. The slow earthquakes usually go unnoticed by people, but they are not smooth and steady at all.
The study was published in Nature Geoscience in June 2018.
The researchers point to a mechanism between the rocks in the San Andreas Fault, which is based in California. Occasionally, the compacting of geological materials results in an increase in fluid pressure that releases the fault. This is what causes the stop-and-go movements.
The movement on the fault commences every year or two and lasted for many months. This results in more stress along certain sections of the fault. An example includes the Parkfield earthquake of 2004 when a magnitude 6 event struck the town.
"What looked like steady, continuous creep was actually made of episodes of acceleration and deceleration along the fault," said Mostafa Khoshmanesh, a graduate research assistant in Arizona State University and lead author. "Based on current time-independent models, there's a 75 percent chance for an earthquake of magnitude 7 or larger in both northern and southern California within next 30 years."
How Did Researchers Discover This Movement?
The researchers discovered that the movement on the San Andreas Fault varied by year. In some years, there was no movement along the central part of the fault. In other years, it moved as much as 4 inches.
To discover these movements, the researchers relied on satellite-based synthetic aperture radar data from 2003 to 2010. They also used previously-researched seismic data to develop a mathematical model.
With the data, they tracked movements on a monthly basis. It also helped them learn about the mechanisms of the earthquakes.
Future Implications Of This Earthquake Data
With this new information about the San Andreas Fault, scientists can use it to learn more about the triggering mechanisms of earthquakes. Some current models for predicting earthquakes usually don't consider the slow earthquakes, but this data proves that it should be factored in.
This new model will help scientists forecast when the next earthquake will strike California. The study proves that seismic activity occurs more often in California, and people should prepare for it.