What drones can teach us about volcanic eruptions
NEW ORLEANS — The Poás volcano in Costa Rica erupted suddenly and violently in late April, hurling chunks of rock into the air, destroying a nearby observation platform and wrecking a single piece of monitoring equipment: a sensor recording gas concentrations in the bottom of the crater. Since it’s not a good idea to walk into the heart of an erupting volcano, Maarten J de Moor, a volcanologist at OVISCORI in Costa Rica, sent in a drone.
Why it matters: de Moor’s drone (and his destroyed sensor) recorded changes in gas concentrations before the eruption, which he presented at the fall meeting of the American Geophysical Union. Such changes can signal if, and when, a volcano might erupt, and may even indicate how large the eruption will be. “If we can measure the gas compositions during eruptions, we can learn about those eruption processes,” says de Moor.
There are several different ways to monitor a volcano, including:
The old-fashioned way, where you dress head-to-toe in protective gear and gather fumes from a vent with a test-tube.
- Pros: More tests can be run in the lab than can be run by an instrument.
- Cons: It’s slow and can take months to do. And, although you can learn a lot about the volcano, real-time data is necessary to learn more about eruptions.
With a permanent sensor, like the MultiGAS sensor de Moor used.
- Pros: Real-time monitoring of the volcano, from the volcanic crater itself.
- Cons: These sensors can only measure the fluctuations of a few gases — so they're good for monitoring, but more detailed lab assessments are still necessary.
With a sensor (in de Moor's case, a miniature MultiGAS) attached to a drone.
- Pros: You can fly into an active volcano after the eruption begins and get a birds-eye view with a camera.
- Cons: Drones can only fly for so long on one battery charge, so monitoring isn't constant. Also, volcanos aren't very hospitable environments. de Moor estmates he can get about 20 flights out of a drone before it's destroyed — he lost one studying a different volcano already.
Yes, but gas sensors aren’t the only thing you can attach to a drone, and inactive volcanoes are also worth monitoring. That's why Einat Lev trekked for days to a remote Chilean volcano (accompanied by an entourage of horses and grad students), hauling batteries, an electric generator and a drone.
What she did: Lev, a volcanologist at Columbia University, uses the unmanned vehicles to scan the topography of cooled lava flows. Although you can get some idea of lava flow structure by looking at satellite images, the level of detail provided by drone can't be matched. By measuring the rocky dips and ridges, she can infer how fast the lava was moving, how hot it was, how liquid or solid it was. Lev also presented her findings at the meeting.
Why she did it: If we learn how a volcano erupted in the past, we might better understand how the same — or a different — volcano might erupt under similar circumstances.
A bonus: Drones might seem expensive, but it costs way more to do this sort of research from a helicopter.