Most likely; there was "a volcanic double event in 536CE and 540CE resulting in cooling." In Norway.
Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500–1250 CE (VIKINGS) University of Oslo.
From the research:
"In Norway, the mid-6th century is associated with profound changes in social organization and material culture, which defines the very transition from the Early Iron Age to the Late Iron Age (500 BCE–550 CE and 550–1050 CE, respectively). Often understood as a turning point in Norwegian prehistory, many archeologists discuss a possible causal relationship with the volcanic double event in 536 and 540 CE (Iversen, 2016; Gundersen, 2019). Bajard et al.""
other option; Is it possible Nordland was Iceland?
The main event described in the tekst Frethorik copies looks like a fissure volcano.
Could be Fagradalsfjall volcano, last eruption 2010, before that 800 years back, leading to the Eldvorp lava fields.
Of course there could be more contestants; Katla erupted 20 times in 1000 years.
Searching for a continental seaflood event that may have made Findas move, I looked at the geology of Turkmenistan east of the Caspian sea, a landslide from there could cause a tsunami. There are faultlines in the country, and the coast of the Kara-Bogaz-Gol lake has had a relatively younger landslide event. I couldn't find any dating on the event though.
https://blogs.agu.org/landslideblog/2021/05/18/kara-bogaz-gol-megaslide-1/