Page 45 - fall2017

BUZZING THE EARTH

A small fleet of drones has revolutionized
fissure observation

by Tim Vanderpool Joe Cook photo

tunningly precise 3-D images of the Sonoran Desert’s surface. They often reach more than a mile in length and
mountains, bluffs and boulder-filled arroyos floated stretch wider than a city street; the biggest can be hundreds
Sacross the computer screen. of feet deep. While they typically occur in remote areas and
But one image made Joe Cook suddenly sit up straight. can go unnoticed for years, they’re dangerous to people and
Cook runs the Earth Fissure Mapping Program for the animals. They also present environmental problems because
Arizona Geological Survey, or AZGS, a state agency operating they divert rainwater that would otherwise spread across the
within the University of Arizona. He spends much of his time landscape and funnel surface pollutants such as pesticides
scanning the terrain with help from Google Earth satellites. directly into the water table.
Among other things, he’s looking for big, ominous cracks That’s why it’s so critical to keep close tabs on fissures.
called fissures. To get up close and personal with the huge cracks in the
Now, a huge one was looking right back at him. It was earth, the AZGS maintains a small fleet of drones, which have
in the Tator Hills Fissure Study Area north of Tucson, near revolutionized fissure observation as well as other tasks like
Picacho Peak. The first fissure there was discovered in monitoring potential landslides and spotting erosion hotspots
1977; today, more than 11 miles of cracks have been mapped after wildfires.
throughout the area. Consider the early 1900s, when crews of geologists would
trek into and spend weeks or months painstakingly
documenting a site. Later, they began surveying
Today, scientists can dispatch with cameras tethered to helium balloons, but that,
too, was slow, and the balloons were difficult to
drones to a site after maneuver.
Today, scientists like AZGS Research Geologist
breakfast and have the data — Brian Gootee can dispatch drones to a site after
breakfast and have the data — complete with
complete with remarkable 3-D remarkable 3-D imagery — before dinnertime.
Among Gootee’s enviable chores is piloting drones
imagery — before dinnertime. over fissures, including the one spotted near Tator
Hills by Joe Cook.
“Brian’s drone was a really neat tool to get a
bird’s-eye view of the fresh fissure,” Cook says, “and
Cook already knew this fissure, which had been around his footage was really nice. Drone footage is much
for a while. But fresh Google Earth imagery showed it more dramatic than ground photos. When fissures are new,
exploding in size. “The fissure extended nearly another mile their walls are vertical and sharp. There is little vegetation
to the south,” he says. “I was pretty surprised at how long the growing along the fissure, so you can see them clearly.”
extension traveled and how big and deep some of the open Behind the controls of a drone, Gootee is always seeking
portions were. I’ve been mapping fissures throughout Arizona the tiny clues — minute cracks or shifting substrate — that
for years, and this was definitely bigger and longer than most.” tell where a fissure is headed. Most images are captured at
Fissures result from excessive groundwater pumping, elevations of 1,000 feet or less. “That gives you a nice, stable,
which causes the earth to subside and break along the photographer’s perspective of very detailed features,” he says.

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