 American tectonic plates meet, one plate is subducted under the other. Their grinding super-heats and melts rock, forming magma and applying intense pressure to Earth’s crust. That pressure can cause tremors. Magma forced upward by the pressure can erupt through volcanoes. That motion is measured by seismometers.
Meanwhile, infrasound detectors detect airwave signals which indicate volcanic activity. These instruments pick up the low-frequency sounds emitted by eruptions, the pressure, explosions, and motion of underground magma. Emitted at a low frequency of less than 20 hertz, the noises are much too deep to be picked up by human ears. However, the noises can be picked up by instruments at stations very far away from where they originate, including stations at the University of Alaska Fairbanks Geophysical Institute.
“It’s a difficult volcano for us to monitor… we only get these reports every now and then, or satellite data. The weather out there is horrible. It’s the central Aleutians, the weather is always bad. [Cleveland] could be erupting little puffs, tiny puffs of ash, on a weekly basis and we would just have no clue. It’s kind of a low-level, almost constantly active volcano. I mentioned that different volcanoes have different personalities -I mean some volcanoes are quiet quiet quiet, have a really big eruption, and go back to sleep- Cleveland is always sort of restless, and giving little belches and things like that. It rarely puts ash up very high or for very long periods of time, so in that sense it’s not as hazardous as some of the volcanoes that have larger eruptions, but it’s a bit of a nuisance for us.” ~ Michelle Coombs, research geologist, Alaska Volcano Observatory
Watch FrontierScientists video Volcano From Space: An astronaut aboard the International Space Station spots an eruption and contacts the Alaska Volcano Observatory.
Laura Nielsen 2013
Frontier Scientists: presenting scientific discovery in the Arctic and beyond
Cook Inlet Volcanoes project
- ‘Activity at Cleveland Volcano, Aleutian Islands, Alaska’ National Aeronautics and Space Administration (NASA) Earth Observatory
- Alaska Volcano Observatory, a joint program of the United States Geological Survey (USGS), the University of Alaska Fairbanks Geophysical Institute (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS)
- ‘Cook Inlet Volcanoes’ project at FrontierScientists featuring volcanologists with the Alaska Volcano Observatory
- Global Volcanism Program ‘Cleveland’ Smithsonian Institution, National Museum of Natural History
- ‘Small Explosive Eruptions at Cleveland in Alaska’ Erik Klemetti, assistant professor of Geosciences at Denison University, for Wired Science Blogs