8/18/2023 0 Comments Most recent volcano eruption 2011So what happens next? Again, based on the pattern observed at past eruptions, an intense swarm of earthquakes lasting a few hours (one to ten hours) will signal that magma is moving towards the surface and that an eruption is imminent. Increasing thermal activity has been melting more ice and there has also been a recent increase in earthquake activity. For example, the volcano has been inflating as new magma moves into the plumbing system beneath it (think of burying a balloon in the sand and then inflating it). Icelandic scientists have been carefully monitoring Grímsvötn since its 2011 eruption, and have seen various signals that suggest the volcano is getting ready to erupt. It is, however, seldom possible to be precise about the exact day. And if these are repeated each time a volcano erupts then it becomes possible for scientists to be more confident that an eruption is likely to happen in the near future. Signs of activityĪ high frequency of eruptions at a volcano allows scientists to detect patterns that lead to eruptions (precursors). Crucially, and with the next eruption in mind, Grímsvötn appears to have a pattern of infrequent larger eruptions that occur every 150-200 years (for example 2011, 1873, 1619), with smaller and more frequent eruptions occurring roughly once a decade in between. The time gaps between eruptions are variable – and, for example, prior to the larger 2011 eruption there were smaller eruptions in 2004, 19 with gaps of between four and 15 years. Grímsvötn is Iceland’s most frequently erupting volcano, and over the past 800 years some 65 eruptions are known with some certainty. This has happened many times at Grímsvötn. This can trigger an eruption – it’s like lifting the lid off a pressure cooker. This happens when the meltwater lake drains – removal of the water from across the top of the volcano rapidly reduces the pressure. Yet another important peculiarity of Grímsvötn is that it can have a hair-trigger response to pressure. Fortunately, the passage of meltwater beneath the ice to its outlet can be tracked, and so roads are closed in good time to avoid travellers getting caught in the flood and killed. This meltwater can escape suddenly, and after travelling southwards beneath the ice for about 45km it emerges at the ice margin as a flood, which in the past has washed away roads and bridges. The roughly 1.5km wide hole melted in the ice by the 2011 eruption. Fresh ice is continually flowing into the caldera, where it melts, and so the water level just keeps rising and rising. This is up to 100 metres deep and has ice up to about 260 metres thick floating on it. And it is along the base of this ridge, under the ice, that most recent eruptions have occurred.Īnother peculiarity is that the heat output from the volcano is extraordinarily high (2000-4000MW), and this melts the overlying ice and produces a hidden subglacial lake of meltwater. Grímsvötn is a peculiar volcano, as it lies almost wholly beneath ice, and the only permanently visible part is an old ridge on its south side which forms the edge of a large crater (a caldera). As a result, the authorities have recently raised the threat level for this volcano. But there are clear signs that the Grímsvötn volcano is getting ready to erupt again. Understandably, any mention of another explosive eruption from an Icelandic volcano will raise concerns in the air travel industry, which is currently reeling from the COVID-19 pandemic. In comparison, the much smaller 2010 eruption of Eyjafjallajökull led to the cancellation of about 100,000 flights. The ice-covered Grímsvötn volcano on Iceland produced an unusually large and powerful eruption in 2011, sending ash 20km into the atmosphere, causing the cancellation of about 900 passenger flights.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |