The eruption in Geldingadalir adjacent to Mt Fagradalsfjall develops as time flies. Currently, periods with a lively eruption, with some magma fountain activity, have alternated with periods where no action is visible in the crater. The average lava discharge figure varies between 7 and 11 cubic metres per second. The lava does flow in rivulets on the surface of the new lava mass but to a large extent also in a plumbing system below the surface. The flow area is 4,3 square km but the lava cover is very thick in places, making up a total mass of 110 million cubic metres.
If the eruption continues for months or even years, a lava shield might slowly be built out of countless lava layers. The effusive eruption has entered successive phases as follows:
- A short lava eruption commences from a new volcano-tectonic fissure with one main crater.
- Up to eight craters are active on the fissure, following an opening farther to the northeast.
- One of the new craters develops into the high, main vent – high magma fountains and increased lava discharge.
- Periodic visible activity follows with lessening fountain activity – somewhat decreased but stable lava discharge.
The 5. phase would include a bubbling, rather quiet lava pond in a top crater of a growing lava shield and lava flowing in a complex system of runnels and lava tubes.
Tourism benefits from the eruption. With rather strict border regulations, Iceland now copes with a growing number of visitors. Thousands of them hike every week to marvel the crater activity and lava flows. Icelanders have flocked to the eruption site as well. A total of over 200,000 people have visited the vantage view points since March 19th.
(Photo: Ragnar Th. Sigurdsson)