In case you're wondering, they went up that hill on the lower right, unpackaged something (one of the three figures I spotted did seem to be wheeling something big behind him or her), and another helicopter appeared and flew over the advancing lobe slowly, twice. They seem to have gone behind the hill now.
Gas measurements, certainly, and probably also thermal measurements, LIDAR, and who knows what else they've got these days.
They'd better hurry up, if they need daylight to work by...
Edit: Went back to the cam and the helicopter they arrived in was revving up. It's just flown off over that hill, so the job is probably done. Still quite a natural spectacle, expecially in the gloaming.
BTW, official eruption updates are here (Icelandic). I find Google Translate handles that a little better than the browser.
Human nature at work, too...In Iceland, they say, folks run toward an eruption, rather than away.
Now with COVID restrictions, they've got this one pretty much to themselves.
Edit: Just read that he (and Lava Dog, presumably) are official: a helicopter pilot, part of the team expertly ferrying experts to and from the eruption site (which even rural Icelanders call out in the boonies).
Þyrluflugmenn Landhelgisgæslunnar hafa haft í nógu að snúast undanfarinn tæpan sólarhring vegna eldgossins í Geldingadal. Þyrlan flýgur nú með vísindamenn, viðbragðsaðila almannavarna og ráðamenn yfir gossvæðið, svo að þeir megi glöggva sig á aðstæðum.