Exploring Bolivia's Highest Volcano: An In-Depth Guide

Bolivia is home to some of the world's highest volcanoes, with both active and extinct volcanoes scattered across the country. The highest volcano in Bolivia is Nevado del Sajama, a glacier-clad stratovolcano that rises to 6,542 metres (21,463 feet) about 20 kilometres east of the Chilean border. The prominent, steep-sided volcano towers about 2,200 metres above its base, and glaciers descend to approximately 5,600 metres. While there is no evidence of Holocene activity, the age of the most recent activity has been debated, with suggestions ranging from the Holocene to the Pleistocene.

Where is the highest volcano in Bolivia?

Bolivia is home to numerous volcanoes, both active and extinct, with some of the world's highest volcanoes found in the country. Bolivia's highest volcano is Nevado del Sajama, a glacier-clad stratovolcano that rises to an elevation of 6,542 metres (21,463 feet) about 20 kilometres east of the Chilean border. The prominent, steep-sided volcano towers approximately 2,200 metres above its base, with glaciers descending to about 5,600 metres.

Nevado del Sajama is part of the Central Andean Volcanic Arc and is composed of andesitic and rhyodacitic lava domes. The volcano borders Volcán Cholcani to the southeast, with flank centres occupying the saddle between the two peaks. While the age of the most recent volcanic activity is uncertain, ranging from the Holocene to the Pleistocene, there is no evidence of Holocene activity.

Another notable volcano in Bolivia is Uturuncu, a dormant volcano located in the Sur Lípez Province of southern Bolivia. At 6,008 metres (19,711 feet) high, it is the highest peak in southwestern Bolivia. Uturuncu has two summit peaks and consists of a complex of lava domes and lava flows, with a total volume estimated to be 50–85 cubic kilometres. The volcano has been the subject of scientific interest due to its long-term uplift, indicating the presence of a large-scale magma intrusion beneath it.

What is its elevation?

The highest volcano in Bolivia is Nevado Sajama, which rises to an elevation of 6,542 metres (21,463 feet) about 20km east of the Chilean border. The prominent glacier-clad edifice consists of an andesitic stratovolcano overlying andesitic-to-rhyodacitic lava domes. Sajama is Bolivia's highest mountain, towering some 2,200 metres above its base.

The age of the most recent volcanic activity at Sajama has been the subject of some debate. While some sources consider it to be Holocene, Pleistocene-Holocene, or Pleistocene, others, such as volcanologist Shanaka de Silva, have noted no evidence of Holocene activity.

Another notable volcano in Bolivia is Uturuncu, which has been described as a ""zombie volcano"" due to its long period of inactivity coupled with ongoing ground deformation. Uturuncu has an elevation of 6,008 metres (19,711 feet) and is the highest peak in southwestern Bolivia. It is a dormant volcano that last erupted around 250,000 to 300,000 years ago.

Uturuncu has been the subject of scientific interest due to its long-term uplift, which has been interpreted as an indication of large-scale magma intrusion beneath the volcano. This has sparked speculation about the potential for future volcanic activity, including the possibility of a supervolcanic eruption. However, as of 2023, there was no evidence of a net uplift in the geomorphology of the region, and the current uplift may be temporary or in its early stages.

What type of volcano is it?

Sajama, a stratovolcano in Bolivia, is the country's highest mountain at 6,542 m (21,463 ft) above sea level. It is a glacier-clad edifice consisting of an andesitic stratovolcano overlying andesitic-to-rhyodacitic lava domes. The age of its most recent activity has been the subject of debate, with suggestions ranging from the Holocene to the Pleistocene. However, there is currently no evidence of Holocene activity.

Uturuncu, on the other hand, is a dormant volcano in the Sur Lípez Province of Bolivia. It is the highest peak in southwestern Bolivia, standing at 6,008 m (19,711 ft) high. Uturuncu is a stratovolcano with remnants of a crater and consists of lava domes and lava flows. It has two summit peaks, and while there is no present-day ice, there is evidence of past glaciation. Uturuncu has been dormant for over 250,000 years, with its last eruption occurring during the Pleistocene epoch.

Both Sajama and Uturuncu are part of the Andean Central Volcanic Arc, and they are characterised as stratovolcanoes. A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers of hardened lava, tephra, and volcanic ash. It has a steep profile and is typically formed by the eruption of viscous lava that cools and hardens before it can spread very far. Stratovolcanoes are often associated with explosive eruptions and the accumulation of pyroclastic materials, which contribute to their layered structure.

In summary, the highest volcanoes in Bolivia, Sajama and Uturuncu, are both examples of stratovolcanoes within the Andean Central Volcanic Arc. They exhibit similar characteristics in terms of their structure and composition, but differ in their recent activity, with Sajama showing signs of more recent activity compared to the dormant Uturuncu.

When did it last erupt?

Uturuncu, the highest volcano in Bolivia, last erupted between 250,000 and 300,000 years ago. While the volcano is currently dormant, it has been steadily inflating for almost 20 years, suggesting that it is slowly reactivating. This inflation has been caused by a large-scale magma intrusion under the volcano, which may be a prelude to large-scale volcanic activity, including "supervolcanic" activity and caldera formation.

Uturuncu is a dormant volcano in the Sur Lípez Province of Bolivia, rising 6,008 metres (19,711 ft) high. It is the highest mountain in southwestern Bolivia and consists of a complex of lava domes and lava flows. Uturuncu has two summit peaks, which are about 1 kilometre apart and separated by a 5,700-metre-high saddle. The volcano is considered dormant, as it has not erupted in the Holocene or recently. However, active fumaroles occur in the summit region, and the volcano has been uplifting at a rate of 1-2 centimetres per year since at least 1992.

The most recent eruption of Uturuncu occurred between 250,000 and 300,000 years ago. This date is based on argon-argon dating of rocks from the volcano, which yielded ages ranging from 1,050,000 ± 5,000 to 250,000 ± 5,000 years ago. The youngest dated lava flow, found just south-southeast of the summit, dates to 250,000 ± 5,000 years ago. While there is no evidence of Holocene activity, the recent unrest manifested by substantial ground deformation and reconnaissance seismicity indicates that a magmatic system is still present, and further monitoring is warranted.

The lack of recent eruptions does not mean that Uturuncu is completely inactive, as it has been undergoing significant changes in recent years. Starting in 1992, satellite observations have indicated a large-scale regional uplift centred on the volcano. This uplift has been interpreted as an indication of large-scale magma intrusion under the volcano and may be a prelude to future volcanic activity, including the potential formation of a supervolcano. The uplift has been relatively consistent, with a rate of 1-2 centimetres per year between 1992 and 2006 and an overall volume change of about 0.4 cubic kilometres during this period. As of 2023, the uplift was still underway, and the total volume change is expected to continue to grow.

In addition to the uplift, Uturuncu also exhibits persistent low-level seismicity, with about three to four earthquakes occurring daily and seismic swarms lasting minutes to hours occurring several times per month. The seismic activity is likely a consequence of the deformation, as intruding magma pressurizes and destabilizes local faults. The combination of uplift and seismicity suggests that Uturuncu is not entirely dormant but is slowly reactivating. However, it is difficult to predict whether this unrest will eventually lead to an eruption, as the behaviour of volcanoes can be highly variable and unpredictable.

What does its future look like?

Bolivia's highest volcano, Nevado del Sajama, is a dormant volcano that last erupted between 250,000 and 300,000 years ago. While there is no evidence of Holocene activity, the volcano is still being monitored as it is not considered extinct. The future of this volcano is uncertain, but its past activity and current state provide some insights into what may happen in the coming years.

The volcano's future activity will depend on several factors, including the movement of tectonic plates, the accumulation of magma, and the presence of any volcanic eruptions or earthquakes in the region. One factor that could influence its future is the ongoing uplift of the region surrounding the volcano, which has been occurring since at least 1992. This uplift has been interpreted as an indication of large-scale magma intrusion under the volcano and could be a prelude to volcanic activity, including "supervolcanic" activity. However, it is important to note that such unrest does not always lead to an eruption.

Another factor to consider is the volcano's location within the Central Volcanic Zone, which spans parts of Peru, Chile, Bolivia, and Argentina. This zone has produced several Holocene volcanoes, and the potential for future volcanic activity in the region cannot be ruled out. Additionally, the volcano's composition and magma genesis will play a role in its future behaviour. Uturuncu has erupted dacite and andesite, and its rocks are vesicular or porphyritic, containing a variety of phenocrysts and xenoliths. The origin of these magmas appears to be related to the underlying Altiplano-Puna magmatic body, which generates melts through differentiation of basaltic magmas.

While the future of Bolivia's highest volcano is uncertain, the current data suggests that the volcano is still active and could produce a significant eruption in the future. The potential impact of such an eruption would depend on its magnitude and the proximity of populated areas. However, it is important to note that supereruptions occur only about once every 100,000 years, and there is no indication of a near-future eruption at Nevado del Sajama. Nonetheless, the volcano's activity and any potential risks it may pose will continue to be monitored and studied by scientists.

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