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Volcano Web Shorts #1
Featuring Angie Diefenbach
My name is Angie Diefenbach. Iím a geologist with the U.S. Geological Survey Cascades Volcano Observatory.
Photogrammetry is a technique by which you can make measurements from photographs. Well I use photogrammetry to study volcanic eruptions.
We use equipment like this that is very standard, just a hand held digital camera. And flying in an airplane or helicopter we take snapshots that look like this from all around the volcano. We put these into a computer software program and add a bunch of points to represent the surface of the dome. And those points get tied together to make a digital model that looks like this of the volcano.
With traditional photogrammetry we had to contract an aerial flight service send out the negatives to be scanned at high resolutions and then a different lab would actually make our digital elevation models. But, now just equipped with a standard digital camera we can produce the same results within a matter of hours.
During the 2009 eruption of Redoubt Volcano in Alaska we would fly out there with a fixed wing airplane or a helicopter and equipped with a digital camera, just a standard one, take snapshots of the lava dome as we fly around it. And then I would take those images, put them into a sophisticated software program and build a digital elevation model of the lava dome. And we found over a three-month period that the lava dome grew to a size of 72 million cubic meters. And on average the growth rate was equivalent to a dump truck per second.
Well photogrammetry provides kind of the fundamental metrics of an eruption. The size and how fast itís growing. And when we use that with other data like seismicity and gas emissions and thermal output we can better understand the volcano as a whole. And that helps us provide better forecasts for what may happen next and that also gets tied into hazards, potential hazards that may occur. (END)
Title: Volcano Web Shorts 1: Photogrammetry
Photogrammetry is the science of making precise measurements by the use of photography. USGS geologist Angie Diefenbach describes how she uses a digital camera and computer software to understand the growth rate of lava domes during a volcanic eruption.
Location: Vancouver, WA, USA
Date Taken: 5/10/2012
Video Producer: Stephen M. Wessells , U.S. Geological Survey
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For more information go to: Cascades Volcano Observatory (CVO) Site
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