The onsets of the eruptions at Hekla are sudden and without much warning; precursory seismic activity, which have been compared with strain data, can announce the onset of an eruption approximately 30 minutes before the breakthrough.
Heklugos gera boð á undan sér; undanfarandi skjálftavirkni sem borin er saman við þenslu gefur um það bil 30 mínútna forskot áður en gos brestur á.