Guatemala’s Volcán de Fuego explosively erupted on Sunday for 16 and a half hours. The devastating event left approximately 25 people dead and nearly 300 injured, a number that is expected to rise. The stratovolcano is one of the most active in Central America and its ability to destroy is directly linked to the lava mixture it emits: Unlike the slow-moving flows recently seen gurgling from Hawaii’s Kilauea volcano, Fuego spits out immensely dangerous pyroclastic flows. Pyroclastic flows are why this eruption has engulfed entire villages and forced approximately 3,000 residents to rapidly evacuate. The United States Geological Survey describes pyroclastic flows as a “chaotic mixture” of hot lava blocks, pumice, ash, and volcanic gas which “destroys nearly everything in their path.” The speed of the flow underlies its danger: Rock fragments within the flow can travel up to 50 miles per hour, and the mixture itself usually moves at tens of meters per second. Meanwhile, the extreme temperature within a pyroclastic flow can ignite fires as it gushes through a landscape: In the Guatemalan towns of El Rodeo, Alotenango, and San Miguel los Lotes, this has turned property to ash. Eddy Sanchez, Ph.D., the director of Guatemala’s seismological, volcanic and meteorological institute told The Guardian that, “Temperatures in the pyroclastic flow can exceed 700 degrees [Celsius] and volcanic ash can rain down on a 15 kilometer [9.32-mile] radius. That could cause more mudflows and nearby rivers to burst their banks.” The BBC reports that Guatemala’s national institute of volcanology, Insivumeh, said that the last pyroclastic flow was recorded at 18:45 local time on Sunday. But the institute warns that people should stay away from the affected ravines, in case there is a “reactivation.” The institute has also warned of the presence of lahar, which may further explain why these flows — which would already be moving fast — have moved at an incredible speed. Also known as volcanic mudflow, lahar is a mixture of water and volcanic debris that emerges as a secondary hazard to pyroclastic flows. Sometimes the consistency is like muddy dishwater, and other times it’s more like wet cement — it all depends on the ratio of water to debris. There’s a currently a warning about the possibility of lahar in place for villages south, southwest, and southeast of the volcano. As a stratovolcano, Fuego is a steep, conical volcano subject to explosive and effusive eruptions. Hawaii’s Kilauea, which has steadily erupted for the past four weeks, is a basaltic shield volcano, which gurgles out a type of basalt lava called tholeiite. It’s a very different type of volcano: Shield volcanos typically only have explosive eruptions if water gets into the vent and 90 percent of the volcano is lava rather than pyroclastic material. For the last month, Hawaiian officials have been trying to persuade those in Kilauea’s path to evacuate. The Guatemalans affected by Fuego tragically did not have that option. According to the USGS, the best advice it can offer for a volcano like Fuego is also the most instinctual: “If you witness a pyroclastic flow, run in the opposite direction as quickly as possible.”<doc-sep>Ash-covered cars near Guatemala's Fuego volcano top stories direct to your inbox SUBSCRIBE Invalid email Sign up to receive our rundown of the day'sdirect to your inbox When you subscribe we will use the information you provide to send you these newsletters. Sometimes they'll include recommendations for other related newsletters or services we offer. Our Privacy Notice explains more about how we use your data, and your rights. You can unsubscribe at any time. Professor David Rothery, Professor of Planetary Geosciences at The Open University, was first keen to clear up a misconception. He said: “The cause of most deaths at the current eruption of Fuego (Guatemala) is being widely reported as a 'river of lava'. “This is probably an inexpert description or a mistranslation. “Fuego does not characteristically produce long fluid lava flows like those currently erupting from Kilauea in Hawaii. Ash from Guatemala's Fuego volcano This is the phenomenon that claimed many lives during the famous AD 79 eruption of Vesuvius that destroyed Pompeii Professor David Rothery of the Open University “They are unlikely to reach inhabited areas, and are not the main hazard at this volcano. “A lava flow (molten rock) rarely travels fast enough to engulf people, and bodies are unlikely to be traceable afterwards. “The videos and still images that I've seen suggest instead one or more pyroclastic flows. “This is when a violently erupted mass of rock fragments and hot gas finds itself too dense to rise as an ash column, and instead cascades down the volcano's slopes.” Pyroclastic flows proved fatal to residents of Pompeii near Mount Vesuvius This is the phenomenon that claimed many lives during the famous AD 79 eruption of Vesuvius that destroyed Pompeii Professor David Rothery of the Open University Professor Rothery said pyroclastic flows could move at speeds in excess of 60 miles per hour, and were hot enough to glow like molten lava. He added: “They can travel further, as well as much faster, than lava flows. “This is the phenomenon that claimed many lives during the famous AD 79 eruption of Vesuvius that destroyed Pompeii.” Professor Rothery said Fuego had been erupting since 2002, and was continuously active in 2017. Guatemala: Ash fills sky as residents flee erupting volcano<doc-sep>When you subscribe we will use the information you provide to send you these newsletters. Sometimes they'll include recommendations for other related newsletters or services we offer. Our Privacy Notice explains more about how we use your data, and your rights. You can unsubscribe at any time. Sign up to receive our rundown of the day'sdirect to your inbox The death toll continues to rise in Guatemala today as charred bodies are pulled out of the debris, with only a fraction of the victims identified so far. El Rodeo, a town which felt the volcano’s full fury when it erupted on Sunday, is almost entirely buried under ash and rock. A makeshift morgue in the nearby city of Escuinta is overrun with desperate relatives searching for missing loved ones amongst the dead. Horrifying photographs and videos have been shared on social media showing the pyroclastic flow soaring into towns, with onlookers suddenly finding themselves with just seconds to get out of the way.<doc-sep>Guatemala: The terrifying moment Fuego volcano erupts top stories direct to your inbox SUBSCRIBE Invalid email Sign up to receive our rundown of the day'sdirect to your inbox When you subscribe we will use the information you provide to send you these newsletters. Sometimes they'll include recommendations for other related newsletters or services we offer. Our Privacy Notice explains more about how we use your data, and your rights. You can unsubscribe at any time. The Fuego volcano, whose name means ‘Volcano of Fire’, erupted on Sunday with catastrophic results, burying people in their homes as the lava suddenly changed course. The most violent eruption the country has seen in more than four decades saw the volcano spew a five-mile stream of molten lava and pyroclastic flow that poured down the streets. Fuego is located on the borders of three of Guatemala’s ‘departments’ - Chimaltenango, Escuintia and Sacatepequez. It lies about 10 miles west of Antigua, and a massive cloud of black smoke rained down for miles reaching the capital Guatemala City, 25 miles away. Officials have reported the dead were so far all concentrated in three towns: El Rodeo, Alotenango and San Miguel los Lotes. El Rodeo has been confirmed as buried, while nearby village La Libertad is unreachable, with fears for the residents growing. One woman in El Rodeo who said she had narrowly escaped as lava poured through corn fields said: “Not everyone escaped. I think they were buried.” What is a pyroclastic flow? Pyroclastic flows are fast-moving currents of extremely hot gas and volcanic matter that pour down volcanic slopes at incredibly high speeds. A volunteer firefighter breaks down They contain a mix of hot lava rocks ranging from pebbles to boulders, pumice, ash and volcanic gasses. Pyroclastic flows can reach speeds of up to 430mph and temperatures of about 1,000 degrees Celsius. A pyroclastic flow typically has devastating results, soaring from the volcano through valleys and towns, destroying nearly everything in its path. The most infamous pyroclastic flow in history occurred in Pompeii, where the flow from Mount Vesuvius buried the Italian city and almost all its residents Guatemala volcano eruption in pictures Wed, June 6, 2018 Guatemala volcano in pictures as Fuego erupts. Play slideshow AFP/Getty Images 1 of 19 The National Disaster Relief Agency of Guatemala shows Volcano Fuego during an eruptive pulse in El Rodeo The USGS website stresses: “If you witness a pyroclastic flow, run in the opposite direction as quickly as possible.” Officials said the volcanic eruption still presented a danger and could cause more mud and pyroclastic flows. Approximately 3,100 people have been evacuated from the areas around Volcán de Fuego so far, and 1.7million people affected. Rescue operations were suspended due to unpredictable weather conditions but were due to resume at 5am local time (12pm BST). Fuego is located on the borders of three of Guatemala’s ‘departments’ Soldiers clear ash off a runway<doc-sep>
At a Glance Pyroclastic flows are a very dangerous phenomenon that occur during some volcanic eruptions. The speed of these flows, as well as the extremely high temperatures, make them almost impossible to escape. Many of the deaths in Sunday's Volcano of Fire eruption in Guatemala were blamed on pyroclastic flows. On Sunday evening, volcanologists watched in horror as Guatemalans stopped to record video of pyroclastic flows that rushed toward them during an eruption at the Volcano of Fire. It's not yet known if any of those people were among the growing death toll, but volcanologists unanimously agreed that it's never safe to stand beneath a pyroclastic flow and gawk at it. These incredibly powerful flows of hot lava blocks, ash, volcanic gas and debris are capable of flipping cars and destroying buildings while moving at speeds of 50 mph or higher, according to the U.S. Geological Survey. For comparison, the fastest lava flows recorded so far during the current Kilauea eruptions on Hawaii's Big Island have only reached speeds of about 600 yards – about a third of a mile – per hour. Pyroclastic flows are also extremely hot, maintaining temperatures as high as 1,300 degrees Fahrenheit, so they can turn snow and ice into hot mud and ignite fires as they travel, the USGS also said. Advertisement (MORE: The Latest Information on the Guatemala Volcano Eruption) In the case of Sunday's eruption in Guatemala, many of the victims were killed by the fast-moving pyroclastic flows, asphyxiated by the ash and dust or burned instantly when the flows finally caught up to them. "We were at a party, celebrating the birth of a baby, when one of the neighbors shouted at us to come out and see the lava that was coming," Hilda Lopez, whose mother and sister were still missing a day after the Volcano of Fire eruption, told the Associated Press. "We didn't believe it, and when we went out the hot mud was already coming down the street." It's also not safe to be on the fringes of pyroclastic flows, as burns and inhalation of dangerous gases are still possible, the USGS also said. If caught downhill of a pyroclastic flow, fleeing the path is the only chance for survival; a building would be blown apart or the intense heat would be too much to survive, Forbes notes.