The Atacama

Geysers at El Tatio

I had the amazing opportunity to be in the Atacama Desert for 6 days (Nov 14-19) helping collect data on geysers in the El Tatio Geyser Field. Dr. Reich’s new PostDoc student, Carolina, recently joined the group after getting her PhD from University of California Berkeley. She has been studying geyser mechanics/fluid flow from a geophysical perspective and is collecting physical data to study the migration/changes of the geysers over time. She and Silvina, an Argentinian who will start her master’s degree at the University of Chile under Dr. Reich in January, were collecting data for two weeks while I joined the expedition during the final week. The plane landed in the mining city of Calama, smack dab in the middle of the Atacama Desert. The copper mine Chuquicamata, the largest copper mine in the world by excavated volume, is just outside Calama. The Atacama is the highest, driest place on Earth, and my skin felt it. Sun protection was a necessity, as UV radiation is extremely harmful. In the high elevations of El Tatio it was actually pretty chilly and windy, which was different from the hot desert air I was anticipating.

San Pedro de Atacama

Street of San Pedro

We stayed in the town of San Pedro de Atacama, more commonly referred to as San Pedro, about 60 miles southeast of Calama. It is a tourist town, as it is the closest city with accommodations near many desert sights. It’s dirt streets are lined with restaurants, tour agencies, souvenir shops, and Northface stores and are constantly full of milling tourists, most of which are from Europe or South America. The day I arrived Carolina and Silvina picked me up at the airport and we did a few errands in the hardware and grocery stores of more populated Calama before driving to San Pedro. Due to the extreme elevations of El Tatio (greater than 4,300 m; 14,100 ft) and the fact that Carolina had some data to go through the first day was spent acclimating to the elevation. Silvina and I had the afternoon to explore some of the sights around San Pedro so we saw some very salty lagoons at the Laguna de Cejar Reserve, which is part of the Salar de Atacama (the largest salt flat in Chile). Silvina took a dip in one of the lagoons and it was so salty that she couldn’t get her head far under water no matter how hard she tried! Next we went to Valle de la Luna, a crater shaped valley that has been carved by water and wind through time. It is part of the Cordillera de la Sal, a small mountain range in the Atacama that is rich in salt from the evaporation of salty lakes and groundwater. There are many very cool salt and rock formations, as well as huge dunes of sand. In San Pedro the days were hot and sunny while the nights were cool, with some days being really windy. San Pedro was definitely a desert oasis, as the green trees that grew next to the stream really made it stand out in the sandy, reddish tan desert rocks.

El Tatio

Collecting GPS points

For the next three and a half days we worked all day long in the geyser field, arriving around 9:30am and leaving between 5-6pm. From San Pedro it’s a two hour drive up to the site along winding mountain roads and flat desert spans. It was a very beautiful drive and I didn’t even mind doing it eight times in total! There are a few tiny villages located next to streams or the occasional lagoon that tend llamas, donkeys, and goats. We also saw lots of wild desert animals, including suri (similar to an ostrich and a flightless bird almost 3 ft tall), vicunas (member of the llama family, but smaller and much cuter), desert foxes, flamingos, and a smallish bird called a gaviota. El Tatio itself has over 80 active geysers and 30 perpetual spouters, making it the largest geyser field in the Southern Hemisphere and the third largest in the world. It is located on the western flank of the Andes and covers a 10x10km area. Geyser activity is mostly confined to three major zones: the Upper Basin, Middle Basin, and Lower Basin. The spring discharges from the Upper and Middle Basins coalesce to form the headwaters of the Rio Salado, which flows west out of the area. The Lower Basin is located about a kilometer west and downstream from the Middle Basin. The Upper Basin is the largest of the fields and contains the most erupting springs of the three basins. Groundwater travels west and heats up due to geothermal activity before reaching the ignimbrites and lavas underlying El Tatio, where the conditions of temperature, pressure, and permeability are right to form geysers. Geysers are defined as a hot spring in which water boils and is ejected into the air in intervals, and due to the great temperature differences deposit the dissolved silica in terraces or cones adjacent to the erupting water. Geysers are very rare, and require much stricter pressure/temperature conditions to form than hot springs, which are very common.

Carolina and Silvina taking a quick break

Silvina and I were in charge of mapping the geysers to compare the changes and possible movement in comparison to the positions measured in 2003 by a different group from the US. I was in charge of getting very accurate GPS points while Silvina measured the sizes of the pools/cones and described their characteristics. All in all we took 87 GPS points in the Upper and Middle Basins of geysers, perpetual spouters, pools, and some extinct cones. Carolina was busy downloading and moving her temperature sensors and GoPro around all day to record all the activity. We got to see the geysers up close and personal, while tourists observed from afar. But as the tours are the most impressive at dawn, when the temperature contrasts between the hot water and below freezing air cause huge steam clouds to condense around the springs/geysers, we were practically alone in the field during the day. It was an amazing experience and I loved being able to do geology in the desert at an enchanting place. The Atacama is most definitely on my list of places to visit again!

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