At the moment when an earthquake strikes, many Californian people ask themselves which fault was the one that ruptured? The San Andreas? The Newport-Inglewood? The Hayward? Scientists are saying that it’s not that easy to find out.
Recent research shows that the Ridgecrest earthquakes, which started in July ruptured at about 20 faults. This is the latest piece of evidence that shows how small faults can produce big earthquakes, and how these earthquakes cover a bigger area than people expect.
Why are these findings crucial for us?
All of these pieces of information are important for us because we can better understand how earthquakes can happen in seconds after a fault ruptures. In those areas with crisscross patterns of faults, an earthquake from a smaller fault can destabilize the bigger earthquakes, things that can lead to a much stronger earthquake.
When it comes to Ridgecrest, the follow-up earthquakes come seconds after – the largest one came 34 hours later. But scientists didn’t always know that smaller faults in California “team-up” to create an even more powerful earthquake.
After the 1992 Landers earthquake took place, researchers found that the 7.3 earthquakes from the Mojave Desert ruptured on five different and separate faults. Years went by, and even more evidence appeared that the earthquakes take place on multiple faults. This was also the case with the 7.1 Hector Mine earthquake, which took place 20 miles east of the Landers quake, and the 7.2 earthquakes on Easter Sunday, back in 2010.
Recent research by experts from NASA’s Jet Propulsion Laboratory and from Caltech suggests how the understanding of scientists of earthquake fault ruptures has evolved a lot. For example, researchers found that the Fourth of July Ridgecrest temblor was formed out of three different earthquakes, of magnitudes of 6.1, 6.2, and 6.2.