Ojos del Salado

Volcanic activity

Ojos del Salado is an active volcano, but the question of whether it should be considered currently (or "historically") active is arguable. According to the Smithsonian Institution's Global Volcanism Program, the most recent known eruption was around 1,300 years ago, with large error. However, there is also some evidence for a minor ash emission in 1993, which would definitely qualify the volcano as historically active. The presence of fumaroles high on the mountain and recent-looking lava flows, albeit of uncertain age, also argues in favor of a categorization as "active." By these definitions, Ojos del Salado is the highest historically active volcano on Earth. If the older date is accepted, the title of "highest historically active volcano" might reside instead with the somewhat lower Llullaillaco volcano, which certainly has erupted in historic times (most recently in 1877) and is considered active. Its last eruption was 1,000–1,500 years ago.

Composition

Salado's rock is predominantly potassium-rich dacite and rhyodacite. Its lavas are high in biotite, hornblende, plagioclase, and opaques, with lower levels of augite, quartz, and hypersthene.

Elevation

The elevation of Ojos del Salado has been the subject of debate. A 2006 article in Andes Magazine offered that Ojos del Salado may be higher than Aconcagua, although the argument was premised on older, less accurate altitude surveys. The results of these older surveys assigned Ojos del Salado an elevation of 7,057 m (23,153 ft), which would have made it nearly 100 m (330 ft) higher than Aconcagua. As early as 1955, an estimate was made that the elevation of Ojos del Salado was 7,100 m (23,300 ft), but that was "simply [...] based on the altitude of the final camp, and the hours of ascent to the summit." In 1956 the first Chilean expedition led by the retired lieutenant René Gajardo measured the height of Ojos del Salado as 7,084 m (23,241 ft) with a pocket pressure altimeter. Apart from being an inexact method, the height shown by the altimeter was far too high as air pressure is generally lower in the afternoon, the time at which the team reached the summit.

An expedition to the area in the 90s claimed that nearby Monte Pissis was even higher than Ojos del Salado. Later measurements using more precise equipment showed that Ojos del Salado is about 100 m (330 ft) higher than Pissis. Furthermore, in 2007 a Chilean–Argentine–European expedition organized by Andes Magazine and Azimut 360 performed a survey on both Ojos del Salado and Monte Pissis using more accurate instruments. It found the former to be 6,891 m (22,608 ft) and the latter 6,793 m (22,287 ft) Although this fits within recent handheld GPS surveys, which have estimated the mountain to be between 6,880 m (22,570 ft) and 6,910 m (22,670 ft), the vertical error margin of the expedition's equipment, 10 m (33 ft), leaves uncertainty as to the mountain's more precise altitude.

Ojos del Salado has two summits, one in Argentina and the other in Chile (the border between the two countries runs between the two summits). The difference in elevation of the two summits is less than 1 m (3 ft 3 in)

Motorized partial ascent

Ojos del Salado has been a popular mountain for attaining the highest altitude aboard a land vehicle. On 22 March 2005 a team led by Matthias Jeschke drove their Toyota Landcruiser 90, V6 at 6,010 meters (19,717 ft) and set a new high altitude record for four-wheeled vehicles. They performed pioneer work by exploring the area around 6,000 m (19,685 ft) for the first time, what paved the way for further attempts to surpass this record. After that, an Extrem Events Team and a VW Team established 4 more high altitude records (Extrem Events 6,010 m on 20 Feb, 2005, VW Team 6,081 m on 17 Feb, 2005, Extrem Events 6,358 m on 2 March 2005, Extrem Events 6,646 m on 13 March 2007). On 21 April 2007, the Chilean duo of Gonzalo Bravo G. and Eduardo Canales Moya beat the previous record when they reached an altitude of 6,688 meters (21,942 ft.) with a modified Suzuki Samurai, setting the latest record for the highest altitude attained by a four-wheeled vehicle. The first high altitude record for trucks was set by a team around Matthias Jeschke. They drove at 6,675 meters (21,899 ft) with a Mercedes Benz Zetros Truck and established a high altitude record not only for trucks but also for diesel-powered motors. On 19 April 2015 Chilean Gianfranco Bianchi reached an altitude of 6,472 m (21,233 ft) with a Suzuki RMZ 450 and set the latest record for motorbikes.