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The eruption started around 16:40 on July 10. Then a crack opened, whose main direction is approx. N30°E from the eastern slope of Litla-Hrút with a direction towards Keili. The crack was in four diagonal pieces with a combined length of 700-800 m. The eruption increased during the first hours and probably reached its peak around 21. Then it started to reduce again. When it was at its peak between 19 and 22 it was considerably more powerful than the initial phase of the eruption in August last year and many times more lava flow than in the initial phase of the eruption in 2021. Gas emissions were high and vegetation was burning at the edges of the lava. The eruption subsided significantly on the night of July 11, and the activity moved mostly to one crater north of the middle of the fissure, 300-400 m northeast of Litla-Hrút. The lava flows to the south, along Litla-Hrút and out onto the lava to its east. Lava flow measurements A group from the Institute of Natural Sciences and the Institute of Earth Sciences flew over the eruption centers around 18 yesterday, on July 11, and took vertical aerial photographs of the lava with the Natural Science Institute's Hasselblad camera. A land model has now been created based on the images and by comparison with a land model (Iceland's DEM), a difference map has been calculated that shows the thickness of the lava. The results of the measurements are that at 18, about 25 hours after the start of the eruption, the volume of the lava was 1.7 million m3, which corresponds to the average lava flow during these 25 hours being about 18-20 m3/s. The flow was highest the night before and probably the maximum flow was over 50 m3/s. The lava flow was probably close to 15 m3/s on the afternoon of July 11th. Measurements of chemical composition The lava that came up at the beginning of the eruption at Litla Hrút is of a similar type to the lava that came up at the end of the 2021 eruption and the one that erupted in August last year. For example, the concentration of MgO is comparable and the ratio of K2O/TiO2 is almost the same (see graph). The lava also contains crystals that shed light on changing crystallization conditions. Chemical composition of lava: MgO wt.% = 8.5 K2O/TiO2 = The chemical composition of the gas is also comparable to that at the beginning of the 2022 eruption, with a relatively high concentration of carbon dioxide (CO2) that probably accumulated in the run-up to the July 10 eruption. Gas emission 5.4 – 11.5 ktons / day SO2 7.1 – 15 ktons / day CO2 These results therefore indicate a connection with the eruption that characterized most of the 2021 eruption, but also the eruption that erupted in 2022. What the exact relationship between these eruptions is calls for more detailed research. It is interesting to note that there is no immediate bubble similar to the one that occurred during the initial phase of these events in March 2021.
