Reflections on fire fracture in Öræfajökull
It has hardly been considered by anyone that Öræfajökull is ruminant after nearly three years of sleep. The indications are threefold;
significantly increased earthquake activity last year
land uplink
obvious signs of geothermal activity in recent weeks
The two aforementioned factors, increased tremor activity and landslides, are a typical prelude to eruption, although such prelude ends more often than not without an eruption. However, it is appropriate to look at the geothermal power in Öræfajökull and wonder what it is to tell us.
Öræfajökull is one of the giant volcanic eruptions that adorn Iceland with Eyjafjallajökull and Snæfellsjökull. It is likely that Snæfell and Hekla can also be incorporated into the firebox category. All of these volcanic eruptions are common in that they stand very high over their surroundings and they do not follow any significant geothermal systems, either in the mountains themselves or in their immediate vicinity. Most of the country's main power stations follow a powerful high-temperature area with cracking systems that extend far beyond the mainland itself, such as in Hengli, Torfajökul area, Katla, Grímsvötn, Askja and Krafla.
Highland areas apply their energy to cooling deposits or magma high in the Earth's crust, usually a few kilometers deep, such as e.g. in Krafla. Cold groundwater silt down to them, warming in with hot vapor or flame and rises to the surface like hot water or steam. It is a prerequisite for the formation of high-temperature areas that a cooling magma shot or magma chamber is grounded. Thus, it can be concluded that the basement chamber is not present in the fire panes, but lies deeper in the crust and below the depth of the water cycle. Thus, the fire rods are formed primarily by the fact that the rocks deep away from the ground pass a straight surface, but its insignificant part sits behind as a basic element that forms a high-temperature system. Therefore, there are no high-temperature systems for the fireworks.
Eldkeilan Öræfajökull is the highest mountain in Iceland. At the top of the mountain is a 5-kilometer wide box, which has probably formed at some time in the mountain. It is believed to be up to 540 m deep and filled with glacial ice. There is no indication that there has been a significant amount of geothermal activity until November 2017. Then a sulfur lamp was found at Kvíá and a sealant began to form in the middle of the box. Both clearly indicate that a new high-temperature area has been created in the middle of the Öræfajökull caldera under a 400-500 m thick iceberg.
From the melting of ice, an assessment of how powerful this new heating system is. The sealant is thought to be about 1 km in diameter and if we say that its average depth is 10 m, the density of ice 900 kg / m 3, the melting temperature of ice is 335 kJ / kg and the melting has lasted for one month, the heat power of this new geothermal area is about 900 MW. It is assumed that the melting has started when tremor activity increased in mid-October. However, if we expect it to start when tremor activity began to increase in May 2017, the heat power is 150 MW. By observing how fast the kettle dips with time, you can get a more detailed idea of the melting speed.
Due to the land level and depth of the groundwater table, this energy can be expected to rise to the bottom of the glacier, which is vaporized, but not as a liquid. If we assume that the vapor is about 250 ° C, the hot and thermal content of such steam is close to 2800 kJ / kg. Spread more than 300 kg / sec of 250 ° C hot steam from the bedrock, melt the ice and dry in clean water. With this steam, there are some non-toxic substances like sulfur compounds and carbon dioxide.
The above accounts are based on the water melting at the bottom of the carton away from there. It is unlikely that it escaped above ground below the glacier ice because it would first have to get out of the 400-500 m deep box, and it is not known of a deep fence in the canopy that could make it outflow. As a consequence, the water must flow back into the ground or simply accumulate on the ash under the ice. If the water flows gently into the ground again, it will come into contact with a rocky rock or magma snap, heat and rise back to the surface, thus increasing the geothermal activity, but another part will appear as an increased flow in rivers and streams on the slopes of the mountain. Assuming that the melting occurred for 1 month, the drainage of the melt would be 3-4 m3 / sec. but only about 0.5 m3 / sec. if the smelt has lasted for 6 months. There is therefore no doubt that increased water flow due to the ice melting phenomenon could be seen as increased flow in rivers and streams.
In the event that the water does not get away, the volume decrease caused by the seal is caused only by the volume of ice melting, minus water condensed from the geothermal gas. This means that the ice that has to melt to form the seal is about ten times greater than the volume of the seal. In that case, the power of the geothermal system would be 1500-9000 MW, depending on the duration of the melt and assumed no water escapes from the box. However, it is considered unlikely that young and unexplored lava layers in the mountain are hriplek so that most of the water flows away as groundwater. Part of the melting water then enters the cycle of the newly formed geothermal system, but part of it flows into rivers and streams on the slopes of the mountain.
Now it is not really known when the melting began, but it has been assumed in the calculations that it lasted one month or since the last shake crisis began in late 2017. If we assume that the tremor activity increased In May 2017, the melting point begins. The melting time is 6 months, and the resulting power is about sixth of the above calculated. If we look at the confidence interval in these calculations, the minimum power of this new geothermal system in Öræfajökull is about 150 MW in the event that all smelt water has run away as soon as the smelting lasts for 6 months and up to 9000 MW if no water has escaped and melting only last for 1 month. Probably the truth is somewhere in between.
It is almost unthinkable that such a powerful high-temperature system will suddenly occur at a place where there was no system before, except that the nitrogen has come very close to the surface, because there is enough good flow of cold ground water to form a very active water cycle. Although there have been no signs of eruption of earthquakes, there is an overwhelming likelihood that a firefire has taken place in Öræfajökull, which has pressed a sour and viscous liqueur wicket up under the surface of the rock below the box, similar to when a toothpaste is squeezed out of a tube.
All of this can be concluded that fire fractures have already started in Öræfajökull and the question is whether and how soon the soil reaches the surface. In any event, there is a fairly high probability that Öræfajökull will die soon.
Ólafur G. Flóvenz
jardfraedikort.is
http://isor.is/frettir/hugleidingar-um-eldsumbrot-i-oraefajokli
