Posts Tagged "lahar"

A Glacier-covered Volcano in Chile: Will It Erupt Soon?

Posted by on Feb 2, 2016 in All Posts, Featured Posts, News, Science, Uncategorized | 0 comments

A Glacier-covered Volcano in Chile: Will It Erupt Soon?

Spread the News:Share Several recent events suggest that a set of glacier-covered volcanoes in the southern Chilean region of Bío-Bío, which have been showing increasing activity since December, may be likely to erupt.  The three mountains, known as the Nevados de Chillán, reach over 3200 meters in elevation, and have a set of glaciers totaling over 2 square kilometers in area on their summits. They have a long record of eruptions, with historical documentation from the 17th century. Radiocarbon evidence records eruptions that took place about 8000 years ago.   The Nevados de Chillán complex, which averaged about one eruption a decade during the 19th and 20th centuries, had been relatively quiescent since an eruption in 2003. Sticking roughly to that schedule, the complex began to show signs of returning to activity with an earthquake in February 2015 which registered 3.2 on the Richter scale. The Chilean National Geology and Mining Service (SERNAGEOMIN) maintained the volcano warning at the lowest level, green, until 31 December, when it issued a yellow warning, signaling an intermediate level of danger. This shift was prompted by the appearance of a new gas vent on 8 December and by a series of over 2000 small seismic events, all under 2.0 on the Richter scale, throughout the month,  which indicated the fracturing of solid rock and the upward movement of magma beneath the surface. This activity has picked up in January, with the opening of a second new vent on 8 January, accompanied by a 2.9 earthquake and a cloud of ash. SERNAGEOMIN and the National Office of Emergencies (ONEMI) installed two webcams near this vent on 27 January. Providing these cameras with material to record, new clouds of ash appeared on 29 January. On 30 January, a crater, about 25-30 meters in diameter, appeared near the other new vents, with gasses, ashes and occasional blocks of cooled lava emerging from it. Temperatures at the summit were about 125º C, which was consistent with ongoing hydrothermal activity but did not suggest that magma, typically closer to 1000 º C in temperature, was approaching the surface.  Taken as a whole, these new activities led ONEMI to create a 2-km zone around the new craters from which people are excluded.  The local sense of concern was increased by the wide availability of images from the new cameras and from an impressive thunderstorm on 31 January, as shown below: @biobio @RoloHahn tormenta eléctrica en la precordillera de chillan pic.twitter.com/u8DXZiSq7I — orlando bustamante (@treguil) February 1, 2016 Dave McGarvie, a volcanologist with considerable experience in ice-covered volcanoes, has been working around Chillán since 2001. In his blog, he offers this overview of the situation: What makes me think that this unrest is likely to lead to an eruption? Well there are two main reasons.   Firstly, there’s clearly been a new heat source introduced into the plumbing system beneath the volcano, and this had drilled a new pathway to the surface leading to bursts of heat escaping through a new vent. This heat source is almost certainly due to magma rising up in the plumbing system. And at the moment there’s a ‘vent-cleaning’ phase in place, with bursts of heat interacting with water contained within the cone (Hydrothermal). There are probably magmatic gases involved as well. These energetic outbursts are cleaning out material in the developing conduit, and possibly also pulverizing (fragmenting) material being blown out.   Secondly, this new vent has developed on the youngest cone at this volcanic complex, which has developed through a long series of eruptions, punctuated by time gaps of a few years to decades. McGarvie’s assessment is that an eruption in the near...

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Roundup: Lava Flows, Pollen Grains and Village Projects

Posted by on Nov 2, 2015 in All Posts, Featured Posts, News, Policy and Economics | 2 comments

Roundup: Lava Flows, Pollen Grains and Village Projects

Spread the News:ShareHazards at Ice-Clad Volcanoes: Phenomena, Processes, and Examples From Mexico, Colombia, Ecuador, and Chile “The interaction of volcanic activity with snow and ice bodies can cause serious hazards and risks[….] Case studies from Mexico, Colombia, Ecuador, and Chile are described. These descriptions depict the way in which the volcanic activity has interacted with ice bodies in recent volcanic crises (Popocatépetl, Mexico; Nevado del Huila, Columbia; Llaima and Villarica, Chile) and how the lahar processes have been generated. Reconstruction of historical events (Cotopaxi, Ecuador) or interpretation of events from the geological remains (Citlatépetl, Mexico) help to document past events that today could be disastrous for people and infrastructure now existing at the corresponding sites. A primary challenge for hazard prevention and risk reduction is the difficulty of making decisions based on imperfect information and a large degree of uncertainty. Successful assessments have resulted in the protection of lives in recent cases such as that at Nevado del Huila (Colombia).” Read more about the study here.   Ancient pollen reveals droughts between Sierra Nevada glacier surges “Hidden below the surface of California’s Central Valley are pollen grains from the Pleistocene that are providing scientists with clues to the severity of droughts that struck the region between glacial periods. The Pleistocene—the age of mammoths and mastodons—occurred between 1.8 million and 11,500 years ago. For this new study, scientists dug up Pleistocene sediment samples containing buried pollen from the Central Valley. They found that pollen samples dated from interglacial periods—years between surges in the mountain glaciers—predominantly came from desert plants. The same sediments lacked pollen from plants of wetter climates.” To learn more about the new findings, click here.   Adapting in the Shadow of Annapurna: A Climate Tipping Point “Rapid climate change in the Himalaya threatens the traditional livelihoods of remote mountain communities, challenges traditional systems of knowledge, and stresses existing socio-ecological systems. Through semi-structured interviews, participatory photography, and repeat photography focused on climate change and its impacts on traditional livelihoods, we aim to shed light on some of the socio-cultural implications of climate related change in Manang, a remote village in the Annapurna Conservation Area of Western Nepal…. Continued development of relevant, place-based adaptations to rapid Himalayan climate change depends on local peoples’ ability to understand the potential impacts of climate change and to adjust within complex, traditional socio-ecological systems.” To learn more about the study and its findings, click here.     Spread the...

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Ecuadorean Eruption Sparks Fears of Glacier Floods

Posted by on Aug 18, 2015 in All Posts, Featured Posts, News, Policy and Economics | 0 comments

Ecuadorean Eruption Sparks Fears of Glacier Floods

Spread the News:ShareAsh erupted from Ecuador’s glacier-covered Cotopaxi volcano last week after seventy quiet years. The debris shot five kilometres into the air, covering homes, cars, fields and roads as it descended, according to the Independent. Patricio Ramon, of Ecuador’s Instituto Geofísico, said the eruption was phreatic, meaning that molten rock encountered water, creating a forceful release of steam. “[I felt] in shock, not knowing what to do when I saw everything was moving. Then a strong smell of sulfur filled the mountain. Tourists were also concerned and wanted to leave as soon as possible,”  resident Franklin Varela told Ciudadana, an Ecuadorean radio station. eruption today at glacier-covered #volcano #Cotopaxi http://t.co/USjPXSmF9S in #Ecuador pic.twitter.com/rsd1p3ftrC — GlacierHub (@GlacierHub) August 14, 2015 Cotopaxi, Ecuador’s second highest volcano, peaks at 5,897 metres and lies 45 kilometres from the capital, Quito. Its glacier, also named Cotopaxi, is considered to be of significant economic, social and environmental importance, according to reports of the United Nations Environment Programme. Meltwater from the glacier provides Quito with water and hydroelectric power, but in the last 40 years, the ice has thinned by more than 38 percent.  Most of this retreat is attributed to climate change, but eruptions can exacerbate glacial retreat by rapidly melting ice and triggering floods. Researchers from Instituto Geofísico told El Universal they considered Cotopaxi one of the most dangerous volcanoes in the world due to its potential for lahars, or mudflows, often triggered by glacial melt. When Cotopaxi erupted in 1877, lahars travelled as far as 100 kilometres from the volcano.   #Cotopaxi volcano crater hot areas in #Landsat 8 thermal band on Aug 10. @JonathanStone10 @IGecuador @eruptionsblog pic.twitter.com/kj3bfZJjzT — Rudiger Escobar Wolf (@rudigerescobar) August 14, 2015 The most recent ash eruptions led to the evacuation of hundreds of residents and livestock from El Pedregal, a community close to the volcano, reported La Hora. Farmers have expressed concerns that the ash that fell on their livestock feed will harm their animals. Residents have been warned to avoid inhaling ash. Quito’s Mayor, Mauricio Rodas, told citizens he would hand out masks and told the city to remain calm. Today’s #Landsat 8 image of Cotopaxi volcano, in between eruptions!!! cc. @IGecuador @JonathanStone10 @eruptionsblog pic.twitter.com/r8WtgNEybD — Rudiger Escobar Wolf (@rudigerescobar) August 14, 2015 Researchers continue to observe Cotopaxi’s activity as the volcano’s activity increases. On Saturday, Ecuador’s president, Rafael Correa, declared a state of emergency. The president’s announcement comes the same week as a series of strikes against his government’s labor policies and changes to the constitution that would allow him to run for president at the end of his term. The army and police have been dispatched and civil guarantees are temporarily suspended. “We declare a state of emergency due to the unusual activity of Mount Cotopaxi,” Correa said. “God willing, everything will go well and the volcano will not erupt.” Map in spanish showing the possible hazards of the #eruption at #Cotopaxi #volcano #Ecuador pic.twitter.com/ObBbnrXi1v — Roberto C. Lopez (@Bromotengger) August 16, 2015 Spread the...

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Volcanoes and Glaciers Shape Alaskan Landscape

Posted by on Aug 6, 2015 in All Posts, Featured Posts, Science | 0 comments

Volcanoes and Glaciers Shape Alaskan Landscape

Spread the News:ShareVolcanic eruptions mark the beginnings of new landscapes. Ash and lava cover existing vegetation and map out a fresh terrain. Though researchers understand how volcanic landscapes evolve over centuries, there is little understanding of how volcanic eruptions have influenced the geomorphology, or the relationship between the Earth’s surface and geological structures, according to Christopher F. Waythomas, from the United States Geological Survey. In a new review of historic volcanic eruptions, Waythomas laid the groundwork for interpreting the effects of volcanic eruptions on shaping the Alaskan landscape. He examined four volcanoes, Redoubt, Katmai, Pavlof and Kasatochi, and found that the volcanoes played a major – if not dominant – role in shaping the ecosystems and landscapes of southern and southwestern Alaska. Alaska, especially the state’s Aleutian arc, experiences volcanic eruptions every one or two years. Most of the time, these eruptions affect the region’s extensive glaciers. Following an eruption, melting glacier water can pick up debris and result in dangerous mudslides, or lahars. Lahars can be so powerful that they change the shape of the landscape they travel through, Waythomas found. They can also change sediment flux in the sea and create lahar blocked lakes. “Given the significant magnitude of many Alaska eruptions and the high frequency of occurrence of eruptive activity, it is worthwhile to examine how eruptive activity and the products of this activity have affected the geomorphic evolution of landscapes throughout the Aleutian arc,” wrote Waythomas.”This task is practical and academic because of the obvious implications for hazards to people, infrastructure, and the environment and for understanding how volcanic systems evolve in an area that is as geologically dynamic as Alaska.”  Because Alaska’s volcanoes erupt fairly frequently, they tend to be covered by a mantle of loose debris, which is easily dislodged by water flows following an eruption. However, the varying nature of eruptions makes understanding the consequences of eruptions and lahars difficult. The state experiences both mild eruptions that spread ash across the surrounding areas and extreme events with heavy lava flow. “The size, characteristics, and unpredictable occurrence of such flows present significant challenges for incorporating large lahars into conventional flood-hazard analyses,” wrote Waythomas. By further studying the secondary effects of volcanic eruptions in Alaska, researchers will have a better understanding of how the events influence the hydrology, biology and form of the landscape, Waythomas added. Spread the...

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Calbuco Erupts a Third Time, with New Mudflows

Posted by on Apr 30, 2015 in All Posts, Featured Posts, News | 0 comments

Calbuco Erupts a Third Time, with New Mudflows

Spread the News:ShareThe glacier-covered volcano Calbuco in southern Chile has erupted for the third time today, after a few days of relative inactivity. It is sending forth a plume of ash 5 kilometers into the atmosphere, and it has created new mudslides, which are  associated with melting of glaciers as well as with recent rainfall. As in its first eruption, seismic activity resumed only briefly before the eruption itself, just after 1pm local time. Though this eruption is, at least at present, smaller than the previous ones on 22 and 23 April, it is still sizable. And it has elicited a stronger reaction, including a public announcement by President Michelle Bachelet within hours of the event. She stated, “All measures are being taken. We are committed not to rest in our efforts to attend to this emergency as quickly as possible.” Both the National Service of Geology and Mines and the National Emergency Office have issued a red alert, the highest level. 6600 local residents have been evacuated, a larger number than for the previous recent eruptions of the volcano. Non-residents have been prohibited from entering the area near the volcano as well. National police have been instructed to enforce this restriction. The new ash fall, and other volcanic debris, are likely to cause additional damage in southern Chile, which has not yet fully recovered from the ash falls of last week. The Washington Post quotes one local resident as saying,  “We were working, cleaning the ash and sand from our homes when this third eruption took place. I feel so much anger and impotence it just breaks me apart.” Meanwhile, the European MetOp satellites have been tracing the plume of aerosols from the earlier eruptions of Calbuco. As this animation shows, the aerosols have now crossed the Atlantic Ocean and have reached South Africa, where dramatic sunsets are now expected. The webcams of the National Service of Geology and Mines have images which are a bit grainy, but are striking nonetheless. For further details about the current eruption, read Erik Klemetti’s recent post  in WIRED.   Spread the...

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