All of that text, to find out they have unveiled nothing.
CA and PacNW volcanoes.
“Geochemical analysis of AD 536 cryptotephras distinguishes at least three synchronous eruptive events in North America.[25] Further analysis correlates one of the eruptions to a widespread Mono Craters tephra identified in northeast America.[25][35] The other two eruptions most likely originated from the eastern Aleutians and Northern Cordilleran volcanic province.[25][36]
https://en.wikipedia.org/wiki/Volcanic_winter_of_536