Toxic Gases at Eruption Site, Eruption Not Over

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Toxic Gases at Eruption Site, Eruption Not Over

By Zoë Robert
Holuhraun lava

Photo: Ármann Höskuldsson/University of Iceland.

Gas measurements at the Holuhraun eruption site indicate that there are currently high levels of sulfur dioxide close to the volcanic fissure. The Scientific Advisory Board of the Icelandic Civil Protection warns that it is essential for those working at the site, such as scientists and journalists, to be equipped with gas sensors and gas masks as the gases are highly dangerous in these levels.

The gas monitoring station was set up as part of the FUTUREVOLC project. FUTUREVOLC is a 26-partner project funded by the European Commission, addressing the geologically-active regions of Europe prone to natural hazards.

Professor in geophysics at the University of Iceland Páll Einarsson said in an interview with ruv.is earlier this afternoon, that it was too early to declare the eruption to be over. 

All road closures are still in effect but the Iceland Air Traffic Control has revoked all restrictions on flights over the area. All airports in Iceland are open.

The Scientific Advisory Board made the following additional conclusions at their midday meeting: 

At 20:00 UTC yesterday, the lava extended over a 3-km-area. This corresponds to a magma discharge of 300 to 500 cubic meters per second. From observations yesterday evening, the volume of erupted lava is between 16 and 25 million cubic meters.

The eruption has not created any ash-fall.

Gas and steam rise to a couple of hundred meters above the eruption site, extending up to 1,200 m downwind.

According to the latest GPS observations, horizontal ground movements continue in response to the dike intrusion. There is no clear sign of a pressure decrease in the dike intrusion in connection with the ongoing eruption, although there are irregularities in GPS displacements at nearby stations. The northern tip of the dike intrusion has not changed to any great extent.

When Sunday’s eruption began, earthquake activity decreased somewhat, although seismicity remains high with over 500 earthquakes detected since midnight last night. Most of the seismicity is occurring in the northern end of the dike intrusion, covering a 15-km-long region that extends partly beneath Dyngjujökull and north of the ice margin.

At 08:58 UTC today, a magnitude 5.0 earthquake was recorded on the Bárðarbunga caldera, and another of magnitude 5.2 at 11:41 UTC in the same region.

It remains unclear how the situation will develop. Four scenarios are still considered most likely:

- The migration of magma could stop, resulting in a gradual reduction in seismic activity and no further eruptions.

- The dike could reach the Earth’s surface causing another eruption, possibly in a new fissure. Lava flow and (or) explosive activity cannot be ruled out.

- The intrusion reaches the surface and another eruption occurs where either the fissure is partly or entirely beneath Dyngjujökull. This would most likely produce a flood in Jökulsá á Fjöllum and perhaps explosive, ash-producing activity.

- An eruption in Bárðarbunga. The eruption could cause an outburst flood and possibly explosive, ash-producing activity. In the event of a sub-glacial eruption, it is most likely that flooding would affect Jökulsá á Fjöllum. However it is not possible to exclude the following flood paths: Skjálfandafljót, Kaldakvísl, Skaftá and Grímsvötn.

Other scenarios cannot be ruled out.

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