Research studying earthquake precursors via analyzing fore-shocks

https://www.nationalgeographic.com/science/2019/08/earthquakes-groundbreaking-catalog-solved-seismic-mystery-foreshocks-southern-california/

This is the important part for analysis

>"That’s why the new quake catalog presented such a tantalizing opportunity. Published earlier this year in Science, that colossal effort pinpointed 1.81 million earthquakes that shook Southern California between 2008 and 2017, all the way down to magnitude 0.3."

https://www.nationalgeographic.com/science/2019/04/every-three-minutes-one-earthquake-california/

- Searching for hidden earthquakes in Southern California

https://science.sciencemag.org/content/364/6442/767

> "This effort resulted in a catalog with 1.81 million earthquakes, a 10-fold increase, which provides important insights into the geometry of fault zones at depth, foreshock behavior and nucleation processes, and earthquake-triggering mechanisms. The rich detail resolved in this type of catalog will facilitate the next generation of analyses of earthquakes and faults."