News from Grímsvötn volcano, Iceland:
Grimsvötn volcano (Iceland): signs of volcano getting ready for eruption
Wednesday Jun 17, 2020 07:13 AM | BY: T
Sampling of gas released from Grimsvötn volcano in June (photo: IMO/Melissa Anne Pfeffer)
One of Iceland's most active volcanoes might be getting ready for a new eruption. Recent observations by scientists from the Icelandic Met Office (IMO) monitoring the sub-glacial volcano lead to this conclusion, IMO reported in a recent press release.
Earthquakes at the volcano during 2020 so far
In the last weeks, several measurements were done at Grimsvötn volcano. They discovered a currently very high output of SO2 gas in the southwest corner of the caldera in Grimsvötn, very close to the eruption sites of 2004 and 2011, a clearly alarming finding: "This is the first time that we measure so much SO2 at a volcano in Iceland that is not in an eruptive phase and its presence is indicative of magma at shallow level", said volcanologist Melissa Anne Pfeffer from the IMO who was among the specialist during the recent measurements. In the area where geothermal activity of the volcano can be detected at the surface, this has also notably increased.
Sulfur dioxide (SO2) is one of the principal volcanic gasses contained in solution in the magma at depth, but released early when magma reaches shallower depths and pressure drops. It can be regarded as one of the most common precursors when volcanoes erupt.
Earthquake activity under the volcano has been slightly elevated at the volcano for a while, along with an inflation of the ground surface. All these data likely reflect the gradual rise and refilling of magma into the volcano's shallow reservoirs.
Rising sub-glacial lake water levels
In addition, the level of the volcano's sub-glacial crater lake has been found to have risen, due to elevated heat release and consequent accumulation of melt-water.
The latter is of particular concern as it increased the likelihood of the occurrence of a glacial flood (jökulhlaup), if the lake suddenly drains from underneath the glacier in a massive flood: once a critical point is reached, the water can lift the ice and create an outlet channel that is quickly widened by a combination of erosion and further melting, resulting in a catastrophic water release that typically devastates the flood planes in its path, destroying almost everything in its path and almost certainly cutting the ring road.
Increased chance of eruption starting at the end of a glacial flood
The next glacial flood of Grimsvötn cold very well also trigger an eruption, as sudden pressure drop above the magma chamber would induce rapid degassing in the magma, similar to the effect of opening a champagne bottle. A glacial flood would also almost certainly occur if an eruption starts without being triggered by a flood in the first place.
According to IMO, "The current conditions of Grimsvötn volcano are such that the water level is rather high and the pressure in the magma chamber below the caldera has reached values comparable to those prior to the last eruption. Therefore, the possibility of an eruption triggered by a glacial flood, which could occur in the coming weeks or months, has to be considered. However, this may not be the case, and the next glacial flood may not lead to an eruption."
When will the volcano erupt?
Grimsvötn is one of Iceland's most active volcanoes, with eruptions occurring every 5-10 years on average, the last having occurred in 1996, 2004, and 2011. Statistically, the next one would be expected to happen any time now or in the few next years.
Links / Sources:
Links / Sources:
Thursday, Mar 27, 2014
A small jökulhlaup (glacier outburst flood) started yesterday from the subglacial lake Grímsvötn and has been discharging into the river Gígjukvísl. ... [more]
Tuesday, Jan 31, 2012
A small glacial flood occurred at Grimsvotn volcano in Iceland on 29 January 2012. The cause of the flood was probably not volcanic, but strong rainfalls and unusually high temperatures that caused melting of large amounts of snow. The flood damaged parts of the Ring Road between Núpsvötn and Gígjukvísl in the Skeiðarársandur flood plain and and east of Gígjukvísl. [more]
Thursday, May 26, 2011
The eruption at Grimsvötn that started off violently last Saturday 21 May seems to be ending (or at least pausing) as ash emissions have dropped to near zero this morning. ... [more]
Wednesday, May 25, 2011
The ash plume from the Grimsvötn eruption has now reached northern Germany, forcing hundreds of flights in and out Hamburg and Berlin to be cancelled today (25 May). [more]
Tuesday, May 24, 2011
The explosive eruption of Grimsvötn volcano continues, but the height of the ash plume has significantly dropped and is estimated 5-7 km this morning 24 May. ... [more]