frontierscientist-AnchorageDailyNews-July 17,2013
View west up the Drift River valley toward Mt Redoubt, Alaska. The entire sector east of the volcano is blanketed in ash deposits. March 31, 2009: Image by Game McGimsey, Alaska Volcano Observatory & U.S. Geological Survey
Volcanoes and Harmonic Tremors
Laura Nielsen for Frontier Scientists –
Volcanoes are an awe-inspiring and hazardous part of our planet. And now, they're being made to sing. Scientists are turning seismic data into audio data in order to grasp just what's going on deep in the Earth's crust, and better forecast future explosive eruptions.
Redoubt 2009
In Alaska, the March 2009 Redoubt eruption was preceded by a series of accelerating earthquakes that were picked up by seismic sensors placed on the volcano's flanks. The distinct, repetitive earthquakes increased in power and frequency. There was a short, calm pause. And then Redoubt erupted with magmatic explosions and emitted towering ash clouds. Twenty eruptions shook Redoubt's innards over the course of two weeks. And just before each eruption the earthquake tempo was intense: Alaska Volcano Observatory scientists could measure 30 new earthquakes starting every second. What caused this unusual eruptive behavior? Understanding more of the processes happening deep within an erupting volcano can improve models that predict the timing and characteristics of future volcanic activity.
Mt Redoubt, Alaska emitting an ash plume. 2009: Image by Game McGimsey, Alaska Volcano Observatory & U.S. Geological Survey
Dangers
That's important. Even volcanoes in remote and sparsely populated places such as Alaska's Aleutian Chain island volcanoes need to be monitored because they can eject large ash clouds into airspace, threatening aviation traffic in the North Pacific air routes connecting North America and Asia. Ash clouds are incredibly dangerous for airplane engines, and when the Alaska Volcano Observatory forecasts high-reaching volcanic ash the Federal Aviation Administration redirects flight paths.
Ash landing in cities poses a health risk to the population, and can cause millions of dollars in damages. The National Oceanic and Atmospheric Administration notes that after the 1992 eruption of Mount Spurr's Crater Peak, the Municipality of Anchorage reported nearly $2 million in damage. Volcanoes that erupt near population centers can release pyroclastic and lava flows, lahars (dangerous mudslides), ash, steam, and dangerous gasses.
Redoubt observations and fieldwork at Mt Redoubt, Alaska, digging out station RDWB. July 1, 2009.: Image by Kate Bull of Cyrus Read, Alaska Volcano Observatory & Alaska Division of Geological & Geophysical Surveys
Volcanic eruptions even have implications for climate, since tiny particles ejected high into the atmosphere can linger and reduce how much incoming solar radiation reaches the ground. Volcanic aerosols have the potential to affect temperatures and crop health across startlingly large regions of the globe.
Monitoring volcanoes
The Alaska Volcano Service monitors northern volcanoes. The AVO is jointly operated by the U.S. Geological Society, the Alaska Division of Geological & Geophysical Surveys and the University of Alaska Fairbanks Geophysical Institute. It works in close conjunction with the National Oceanic and Atmospheric Administration's National Weather Service to provide early warning of volcanic activity.
Volcanoes are monitored and studied with a complex suite of tools. Seismic sensors on the ground feel for earthquakes, wile GPS systems note the swelling of mountain slopes that sometimes precede an eruption. Webcams point toward peaks to spot signs of fumes or ash being released. Information from meteorological weather offices can help track wind and ash directions. Satellites are used to notice hotspots or ash trails. Even word-of mouth information from plane pilots and fishermen help the AVO in their volcanic vigil. You can report eruption clouds or ash fall in Alaska online at https://www.avo.alaska.edu/ashfall/ashreport.php - "Is Ash Falling?"
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