Unfortunately, the highest point of the smaller island of Therasia where I have been working (Mount Viglos) at only 295 m is covered in Minoan pyroclastic deposits.ĭeposits from the Minoan eruption in a quarry cliff near Fira on Santorini. Mount Profitas Ilias for example, at 552 m appears to have escaped most of the pyroclastic flows. However, some of the high points appear to have been untouched. On Santorini, most of the islands are covered in deposits from Minoan pyroclastic flows. In order to escape them you need to get up high. They can reach speeds of up to 300 mile/hour if you are in their path there is no escape. The first thing you should know if you want to escape from a pyroclastic flow is that you can't outrun them. The most destructive force of a Minoan-sized eruption, locally at least, is the pyroclastic flows. The following is just my ponderings on the workings of pyroclastic flows. The only way to stay safe on these sorts of volcanoes when they are active is to stay away, and to follow official evacuation orders and exclusion zones. I should also point out that this is in no way official advice, please don't try this at home. Small pyroclastic flow at Mayon volcano in the Philippines on September 23, 1984.
Just for fun, however, I still planned out how I would escape a larger eruption. These would most likely occur on the small, uninhabited island of Nea Kameni at the centre of the caldera, and wouldn't cause too much destruction on the surrounding islands where everyone lives. Most likely the next eruption will be a small effusive one (with lava flows) or a small explosive one (dusting the islands with a thin ash or pumice layer). So just a quick post until I get back and can write up the trip in some more detail.įirstly I should point out that the chance of a Minoan-sized eruption any time soon is remote, and we would probably have a fair amount of warning first. To pass the time, I have been playing a game of "what would I do if the volcano erupted now", thinking about pyroclastic flows and trying to work out where would be safest. Walking past deposits from the last big eruption, the Minoan, I can't help but be impressed by the size of some of the chunks of rock the eruption transported. I am currently on fieldwork on Santorini, which does involve a fair bit of walking from outcrop to outcrop. A mudflow containing volcanic material, called a lahar, may also form when the rock of the pyroclastic flow mixes with water to become a quickly moving slurry.Simple answer: Just don't be there in the first place. Floods may also occur when the flow of hot material melts snow and ice, swelling rivers and streams beyond their banks. Pyroclastic flows may result in flooding as streams are blocked or rerouted by the flow. Not only does it destroy living material in its path, it often leaves behind a deep layer of solidified lava and thick ash. Such a flow can transform the landscape drastically in a short period of time. Above this, a thick cloud of ash forms over the fast-moving flow. Along the ground, lava and pieces of rock flow downhill. Pyroclastic flows often occur in two parts. Pyroclastic flows can also form when a lava dome or lava flow becomes too steep and collapses. Another cause is when volcanic material expelled during an eruption immediately begins moving down the sides of the volcano. A common cause is when the column of lava, ash, and gases expelled from a volcano during an eruption loses its upward momentum and falls back to the ground. It may move at speeds as high as 200 m/s.
A pyroclastic flow is extremely hot, burning anything in its path. It occurs as part of certain volcanic eruptions. A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases.
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