Salar de Gorbea and Lastarria Volcano Expedition: Geothermal Fields and Sulfur in the Deep Puna

The Salar de Gorbea and Lastarria Volcano expedition is a 4-day, roughly 1,300-kilometer high-mountain 4x4 journey that starts and ends in Copiapó. The route crosses the Salar de Pedernales basin and climbs unmarked tracks to 4,600 m to set up base camp in front of the most active solfatara field in Chile, finishing with the summit push on Lastarria Volcano (5,697 m) among pure sulfur fumaroles and untouched hydrothermal deposits.

Extreme Geography on the Border of Atacama and Antofagasta

The area that includes the Salar de Gorbea and Lastarria Volcano (also called Cerro Azufre) lies on the border between Chile and Argentina, right at the hinge between the Atacama and Antofagasta regions. It is one of the most empty and isolated geographic quadrants of the Central Andes: there are no permanent settlements, police checkpoints, cell coverage or mechanical assistance within more than 160 kilometers.

While the commercial routes out of San Pedro de Atacama or the Paso San Francisco highway concentrate most guided visits, heading toward Gorbea means entering the deep Puna in complete self-sufficiency. Here the landscape combines salt basins saturated with yellow evaporites, soot-colored volcanic scoria fields and columns of magmatic steam roaring under the pressure of the Andean crust.

The Salar de Gorbea Phenomenon: Evaporite Basins and Pure Sulfur

At an average altitude of 3,950 m, the Salar de Gorbea is one of the least altered evaporite basins in northern Chile. Unlike the Salar de Atacama or the Salar de Maricunga, where rough crusts of white or brown halite dominate, Gorbea has a geochemistry dominated by sulfate inputs and acidic hydrothermal emissions coming from the adjacent volcanic range.

During our scouting trips to the salar we confirmed that its most striking visual feature is the sectors with intense yellow coloring. These blankets of native sulfur precipitate from hot fluids loaded with hydrogen sulfide that come into contact with the cold air of the high plateau, crystallizing into brittle crusts over volcanic silt.

The fragility of the ground demands extreme caution when driving:

• Danger of getting stuck in hidden brine: Crusts of sulfates and gypsum can look solid on the surface but hide hot, soft, wet mud. Driving vehicles onto the white or yellow basin causes immediate oil pan damage and sinking where the tires spin freely.
• Motorized traffic is prohibited on the salar: We keep the trucks strictly on the perimeter tracks of compacted gravel and reach the geological study areas on foot. Tire tracks on the salt floor destroy bacterial microstructures and stay visible for decades because there is almost no dissolving rainfall.
• Acidity of surface waters: The shallow lagoons of the Salar de Gorbea have an extremely acidic pH and a high load of dissolved metals, so washing personal gear or handling the water without nitrile gloves is dangerous.

Lastarria Volcano (5,697 m): The Most Active Fumarolic Laboratory in the Andes

Lastarria Volcano, also known to the old pirquineros of the Puna as Cerro Azufre, is a composite stratovolcano that rises directly north of the Salar de Gorbea. Its conical silhouette dominates the Andean horizon, but its distinguishing feature is not its absolute height but its fierce surface geothermal activity.

Lastarria hosts the largest system of solfataras and active fumarole fields in Chile. On its south and southeast slopes, between 4,900 and 5,300 m, there are four main fumarole fields with hundreds of sulfur vents and chimneys where magmatic gases escape at audible pressures with constant hissing.

Geothermal Parameters of the Solfatara System

1. Exit temperatures: Direct measurements at the fumarole mouths record temperatures that often range around 150 °C and exceed 250 °C to 300 °C at the main vents.
2. Sublimation and sulfur flow: The steam carries sulfur dioxide ($SO_2$) and hydrogen sulfide ($H_2S$) which, on cooling abruptly at the vent mouth, sublimate from gas to solid, forming tubular chimneys of lemon-yellow elemental sulfur. In periods of high emission, small flows of liquid sulfur even form over the volcanic rock.
3. Inflation of the Lazufre Complex: Geologically, Lastarria is part of the Lazufre magmatic inflation area (between Lastarria and the Cordón del Azufre). Satellite studies using interferometric radar (InSAR) have determined that a vast area of more than 1,000 square kilometers undergoes a continuous millimeter-scale uplift every year due to the intrusion of active magma about 9 to 10 kilometers deep.

Journey Roadmap: 4 Days from Copiapó (1,300 km)

The ascent and exploration of this area are organized with departure from Copiapó to build a gradual altitude gain that minimizes the risk of severe acute mountain sickness.

 Copiapó (390 m)
   │
   ├─► Day 1: Diego de Almagro ➔ Cuesta Montandón (3,700 m) ➔ Salar de Pedernales (3,370 m) [Camp 1]
   │
   ├─► Day 2: Mining tracks ➔ Salar de Gorbea (3,950 m) ➔ Lastarria BC (4,600 m) [Camp 2]
   │
   ├─► Day 3: Summit push Lastarria Volcano (5,697 m) ➔ Return to Lastarria BC [Camp 3]
   │
   └─► Day 4: Leave-no-trace camp breakdown ➔ Off-road descent ➔ Diego de Almagro ➔ Copiapó

Day 1: Copiapó – Diego de Almagro – Salar de Pedernales (3,370 to 3,700 m)

We leave early via Route 5 and Route C-17 toward Diego de Almagro, the last town with commercial supplies. Here we fill the main tanks to 100%, load reserve jerry cans and check tire pressures. We climb through Llanta and the Quebrada de Asientos, crossing the Cuesta Montandón (3,700 m) until we enter the Salar de Pedernales basin.

We set up the first camp in wind-sheltered spots at around 3,400 m. This first night at moderate altitude triggers the erythropoietic response and lets us assess each member's oxygenation. If the weather allows, we take an easy walk to the edges of the basin, linking up with the area of the Salar de Pedernales and Laguna Turquesa tour.

Day 2: Salar de Pedernales – Salar de Gorbea – Lastarria Base Camp (4,600 m)

A day of technical 4x4 driving and off-trail navigation. We leave the main tracks and travel along dry gully beds, volcanic sand plains and rocky scree passes heading northeast. We skirt the southern edge of the Salar de Gorbea, where we stop to look at the pure sulfur formations and the evaporite blankets.

In the afternoon we take on the climb toward the southwestern base of Lastarria Volcano. The terrain requires driving in low range (4L) to avoid overheating the transmissions on loose gravel ramps. We set up Base Camp at about 4,600 m. We anchor the high-mountain tents with heavy volcanic rock walls because of the night gusts that often exceed 70 km/h.

Day 3: Summit Day (5,697 m) – Solfataras and Crater Rim

We start walking between 04:00 and 04:30 AM with headlamps and temperatures of -15 °C. The trail runs over ridges of scoria and unstable rubble. Around 5,000 m we reach the flank of the middle solfatara field: here it is decisive to assess the prevailing direction of the west wind to go around the gas plumes and put on the chemical protection mask.

Once past the fumarole belt, we take on the final slope of loose scree that connects to the crater rim. After 6 to 8 hours of sustained effort we reach the summit of Lastarria Volcano (5,697 m). The panorama from the top takes in the Salar de Gorbea to the south, the Salar de Pajonales to the north, the neighboring cone of the Cordón del Azufre and the desert immensity of Salta province toward Argentine territory. The descent follows direct scree slopes in about 2.5 hours, returning to camp for intensive hydration and rest.

Day 4: Camp Breakdown and Return to Copiapó

We break down camp, removing all solid and organic waste under a strict leave-no-trace protocol. The 4x4 caravan heads back along the pre-Andean tracks until it links up with the C-173 and descends toward Diego de Almagro and Copiapó, completing a circuit of 1,300 kilometers of driving.

Physical Requirements, GPS Navigation and Why This Is Not a Conventional Tour

This expedition is not a recreational outing or a conventional photo safari. It is a high-mountain journey over rugged terrain that demands preparation and technical competence:

1. Physiological Challenge and Sustained Hypoxia

Sleeping at 4,600 m subjects the body to an oxygen partial pressure equivalent to almost half of what is available at sea level. Participants must have previous experience sleeping above 3,800 meters and must have checked their cardiovascular response on earlier acclimatization outings. You can check how oxygen availability varies with altitude using our altitude to oxygen calculator.

2. Satellite Navigation and 4x4 Driving on Virgin Terrain

More than 60% of the off-pavement route has no road signs and no consolidated tracks on standard offline navigation maps. Orientation depends on waypoints loaded beforehand into satellite GPS receivers, visual reading of gully crossings and two-way satellite communication (Garmin InReach). On our trips we operate with two trucks in tandem: if one vehicle suffers a serious mechanical failure or gets stuck in volcanic sand, the second unit guarantees rescue and self-sufficient evacuation.

3. Toxic Risks in Fumarole Zones

Walking among active fumaroles at more than 5,000 meters of altitude adds a risk variable absent from conventional Puna peaks such as San Francisco volcano or Cerro Toco. Sulfur dioxide ($SO_2$) reacts with the moisture of the respiratory mucous membranes to produce sulfurous acid, which causes immediate coughing fits, eye irritation and a feeling of suffocation. Carrying half-face elastomeric respirators with combined cartridges for acid gases and organic vapors is mandatory.

You can plan your travel and walking times on scree slopes using our Naismith time calculator.

Recommended Gear for the Deep Puna

To handle the temperature swings of the Puna (up to 20 °C at midday in direct sun and -18 °C at dawn in base camp), we recommend the following gear breakdown:

Clothing and Apparel

• First thermal layer: Top and bottom set of merino wool or quick-drying water-repellent synthetic.
• Second insulating layer: Technical fleece jacket (Polartec Thermal Pro or equivalent) and softshell windproof jacket.
• Third waterproof layer: Jacket and pants with a three-layer waterproof breathable membrane (Gore-Tex or equivalent).
• Extreme warmth layer: High-mountain down jacket of 750 to 800 fill power for camp and summit day.
• Extremities: Thermal contact gloves, down expedition mittens, balaclava, thermal hat and high-weight merino wool socks.
• Eye protection: Wraparound Category 4 sunglasses, mandatory because of solar radiation and the albedo of the salt crusts.

Camp and Vehicle Logistics

• Sleeping bag: Down fill with a certified comfort rating (EN 13537) of at least -15 °C to -20 °C.
• Ground insulation: Inflatable pad with a high R-value (minimum R 4.5) combined with a closed-cell foam pad.
• Mechanical self-sufficiency: 12V compressor for adjusting pressures, recovery boards, kinetic strap and two spare tires mounted on rims.

If you lack technical clothing or 4-season tents, or you need a vehicle prepared for the Atacama mountains, check the options for mountain gear and 4x4 truck rental in Copiapó. You can also read our guide on 4x4 logistics and huts on the Seismiles Route.

How to Organize Your Expedition with Vulcano

The Lastarria ascent can be arranged as part of our guided Lastarria Volcano ascent program or within a custom expedition circuit of off-road exploration through the most remote salars of the Atacama basin.

At Vulcano Expediciones we coordinate the entire operational chain:

• High-mountain guides with remote medical certification (WFR) and experience in the Puna.
• 4x4 trucks equipped with two spares, reserve fuel and heavy recovery gear.
• Four-season geodesic high-mountain tents suited to whiteout winds and gales.
• Complete energy-rich meals designed for efficient digestion at altitude.
• Active safety: Garmin InReach satellite communication, expedition first aid kit with altitude sickness medication, daily pulse oximetry and a backup medical oxygen cylinder.

Frequently Asked Questions

Is it dangerous to breathe the sulfur fumaroles of Lastarria Volcano?

Yes. The gas released by the fumaroles contains sulfur dioxide ($SO_2$) and hydrogen sulfide ($H_2S$) in concentrations that irritate the respiratory system. If the gas plume drifts toward the route because the wind changes, breathing it without protection causes acute throat inflammation and bronchial spasms. Masks with certified filters for acid gases are mandatory, and you should go around the chimneys, always keeping to the upwind side.

Can the Salar de Gorbea expedition be done in a single private vehicle?

We do not recommend it under any circumstances. The area has no regular vehicle traffic, drinking water or phone signal at all. If a lone vehicle suffers a broken axle shaft, deep sand entrapment or an engine failure, the response time for a rescue can take days. Responsible journeys into the deep Puna are always run with a minimum of two 4x4 trucks in tandem and satellite rescue equipment.

What is the difference between the route to Lastarria from Copiapó and the route from San Pedro de Atacama?

The approach from Copiapó climbs through the Salar de Pedernales and the Salar de Gorbea, covering about 1,300 km in total along historic mining gullies and salars with native sulfur. Access from San Pedro de Atacama heads south through Peine, Tilomonte and the Salar de Pajonales. Both routes converge at the base of the volcano, but the itinerary from Copiapó lets you fit the geothermal phenomenon of the Salar de Gorbea into a single expedition.

What is the best season for the journey to the Salar de Gorbea and Lastarria Volcano?

The most stable window covers the months of October to December and March to May. During this period you avoid the snowfalls and electrical storms of the altiplanic winter (January to March) and the hurricane-force whiteout winds of the polar winter (June to August), when night temperatures at base camp drop below -25 °C with roads blocked by accumulated snow.