Moderate

While the 10 Miyake events known about over the past15,000 years seem relatively infrequent, we don’t know whether they occur with any sort of pattern. It is also unclear why the sun produces them. “They’re not part of what people thought was the sun’s potential behavior,” says Heaton. “We don’t even really know whether they are a totally special behavior of the sun or just the extreme ends of the more moderate solar storms that we see all the time.”

“This is maybe the biggest solar storm we’ve seen in the past, but I think we’ve just scratched the surface,” says Raimund Muscheler at Lund University in Sweden. The carbon-14 spike doesn’t tell us about the gamma rays or plasma emitted during solar storms, though, he says, because carbon-14 is only produced from the sun’s high-energy particles such as protons.
–New Scientist