Of the 62 volcanoes in the Central Volcanic Zone of the Andes, Lascar (5592m / 18,346ft) is the most active. It went through a cycle of dome building and eruption until a large (VEI 4) event destroyed the dome in 1993. Activity resumed in the mid-to-late 2000s, and then it woke up again in October 2015 with a small phreatic eruption, a couple of weeks before we planned to ascend. Our colleagues at NASA detected a large hotspot from space while we were there.
On the Trail by Fire, we couldn't get enough of Lascar. Literally -- we found it a challenge to collect enough volcanic gas. So we innovated and iterated, tackling the volcano time after time with our new tools. In the end, we climbed Lascar four times. In the process, we may have set some world records: longest improvised volcano gas collecting pole, and the highest flight of a quadcopter above sea level.
Trail by Fire's preferred route to Lascar involves driving across 40km of salt flats (Salar de Atacama) to reach the village of Talabre. With a population of 64, Talabre lacks many of the amenities provided in San Pedro de Atacama, the traditional jumping-off point for Lascar. For example, there is no petrol station. On the other hand, it's 1100m further above sea level (a boon for acclimatization), it's an hour closer to the volcano, and the traditional village cooking at hostal Huaytiquina is delicious.
Out the window from Talabre, Lascar's impressive gas plume appears an easy target for study. Once at the crater rim, however, it's a different story. To measure gas composition and take samples, we need to get right into the plume. At many volcanoes, this is easily accomplished by standing on downwind side of the crater rim. Lascar's enormous active crater, however, is 600m across. The geometry means that the plume tends to float off above our heads. TBF came up with two ways to tackle this problem.
One solution is to fly quadcopters. On Lascar, there's about half of the air pressure at sea level, which has a major impact on available thrust, reducing stability. Although we designed our quadcopters to handle high altitudes, this would be the highest we'd tested them. In fact, to the best of our knowledge, this would be the highest above sea level any quadcopter has ever flown. We did it, and it worked. TBF made several flights out over the crater and up into the plume.
The quadcopter flights allowed us to see the bottom of the crater in high resolution for the first time. Although our hopes of discovering a lava lake deep in the crater were dashed, it was useful to learn which fumaroles were active and where. We also flew a quadcopter with gas sensors on it into the plume and were excited to analyse the data. Unfortunately, it turned out that a gas tube had come loose while transporting the quadcopter to Lascar, rendering the data from that particular flight useless. Nevertheless, it was a good demonstration of the technology (TurboAce Matrix + Erle-brain v1.1 + TBS CrossFire -- more details in an upcoming post) and paved the way for flights at the next volcano.
Yves and Ian worked on a simpler approach to the problem, without the stability and battery life limitations posed by a flying platform. It's called the Sampling Technology for In-situ CO2 Kollection (STICK) and is based on high-tech modular composite materials. In other words, walking poles and tent poles zip-tied together. STICK significantly increased the concentration of the gas we were able to collect.
We also conducted remote sensing, usually from the south side of the volcano but one day the plume direction inspired us to try operating the scanning DOAS and UV camera from a different location. On the way, we encountered some fellow Land Rover enthusiasts from Italy. We planned to get in touch afterwards via their website, but can't seem to find it! Consider this a missed connections ad.
One thing all these Atacama volcanoes have in common (in Atacommon?) is dusty off-road driving, and Lascar is no exception. We'd been blowing out our air filter with compressed air at every opportunity, but after Lascar it was clearly time for a change. We put in a fresh air filter at Antofagasta and rolled on south towards greener climes.