Tree rings tell scientists a lot beyond just how old a tree was. They show the conditions the tree was subject to for every year of its life, including droughts and fires. Scientists can also use charcoal from trees to date old earthquakes but relying solely on the radiocarbon dating of charcoal of a long-lived tree can be messy. Now, researchers have come up with a new statistics-based method of dating charcoal samples in stratigraphic layers to estimate the ages of past earthquakes that gets around the challenges. Results from one California site indicate two large earthquakes occurred within 68 years of the 1906 San Francisco quake, but that the northern San Andreas Fault also went several hundred years without large earthquakes.
https://temblor.net/earthquake-insights/tree-rings-and-statistics-team-up-to-date-earthquakes-11251/
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