Miyake event

A Miyake event is an observed sharp enhancement of the production of cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope 14C in tree rings, as well as 10Be and 36Cl in ice cores, which are all independently dated. At present, five significant events are known (7176 BCE, 5259 BCE, 664–663 BCE, 774 CE, and 993 CE) for which the spike in 14C is quite remarkable, i.e. above 1% rise over a period of two years, and four more events (12,350 BCE, 5410 BCE, 1052 CE, 1279 CE) need independent confirmation. It is not known how often Miyake events occur, but from the available data it is estimated to be every 400 to 2,400 years. A Miyake event occurring in modern conditions would cause severe damage to global technological infrastructure such as satellites, telecommunications, and power grids. There is strong evidence that Miyake events are caused by extreme solar particle events and they are likely related to super-flares discovered on solar-like stars. Although Miyake events are based on extreme year-to-year rises of 14C concentration, the duration of the periods over which the 14C levels increase or stay at high levels is longer than one year. However, a universal cause and origin of all the events is not yet established, and some of the events may be caused by other phenomena coming from beyond the Solar System, such as a gamma-ray burst. A 2023 study dated the largest known Miyake event between 12,350 and 12,349 BCE, identified by an international team who measured radiocarbon levels in ancient trees recovered from the eroded banks of the Drouzet River, near Gap in the Southern French Alps. Although the 14C increase was nearly double that for the next strongest spike in 774 CE, the...