Photo Friday: Nevados de Chillán at Risk of Volcanic Eruption

Chile’s National Geology and Mining Service has issued an orange alert for Nevados de Chillán, a complex of snow-capped stratovolcanoes located in the Ñuble region near the country’s border with Argentina.

The agency’s level-orange alert signifies a significant uptick in volcanic activity.

According to NASA’s Earth Observatory: “Like other historically active volcanoes in the central Andes, the Nevados de Chillán were created by upwelling magma generated by eastward subduction, as the dense oceanic crust of the Pacific basin dove beneath the less dense continental crust of South America. The rising magmas associated with this type of tectonic environment frequently erupt explosively, forming widespread ash and ignimbrite layers. They can also produce less explosive eruptions, with voluminous lava flows that layer together with explosively erupted deposits to build the classic cone-shaped edifice of a stratovolcano.”

According to Chile’s geology and mining agency: “The main volcanic hazards associated with the CVNCh correspond to lahars, debris flows and lava flows, channeled through the main valleys: Estero Renegado, Estero Shangri-La, Chillán River, Estero San José, Santa Gertrudis River, Gato River and Las Minas River . The generation of lahars configures the greatest potential danger for the population surrounding the volcano, given its proximity to the channels and the amount of snow and ice on the summits of the complex. Ash fall determined by the dominant wind direction.”

A view of Nevados de Chillán from the International Space Station (Source: NASA)

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Photo Friday: These Glacier-Covered Volcanoes in Chile Could Soon Erupt

Stretching over 7,000 kilometers across seven countries, the Andes are the world’s longest mountain range. They make up the southeastern portion of the Ring of Fire and are well-known for their abundant volcanoes.

The Chilean Andes are home to 90 active volcanoes, all monitored by the Chilean National Geology and Mining Service (Sernageomin). The agency categorizes volcanic activity using four distinct alert levels: green (normal level of activity), yellow (increased level of activity), orange (probable development of an eruption in the short-term), and red (eruption is ongoing or imminent). Increased volcanic activity is associated with frequent earthquakes; plumes of gas, rocks, or ash; and lava flows.

Two areas monitored by Sernageomin are currently showing signs of increased activity: the Nevados de Chillán and Planchón-Peteroa volcanic complexes. The agency issued orange and yellow alert levels for them, respectively.

A satellite image of the Nevados de Chillán volcano complex, showing the glacier-covered volcano peaks (Source: Sernageomin).

Nevados de Chillán Volcanoes: Orange Alert

The Nevados de Chillán volcano complex is comprised of several glacier-covered volcanic peaks. When these volcanoes erupt, the glacial ice sitting atop them melts and mixes with lava, which can result in dangerous lahars, or mudflows. Several small earthquakes and the formation of new gas vents led Sernageomin to issue a yellow alert on December 31, 2015. (To view a detailed map of the Nevados de Chillán complex, click here.)

On April 5, 2018, Sernageomin upgraded the Nevados de Chillán’s yellow alert to an orange alert, following thousands of tremors and a thick, white column of smoke rising from the area. This signaled the likelihood of an eruption in the near future.

Sernageomin’s most recent volcanic activity report for Nevados de Chillán, issued on February 11, 2019, cited persistent seismic activity, which is directly related to increased frequency of explosions, along with the growth and/or destruction of the lava dome that lies in the crater. The expected eruption is most likely to have moderate to low explosive power, but sporadic observations over the last year have shown higher than average energy levels.

On February 15, 2019, the Volcanic Ash Advisory Center in Buenos Aires documented a volcanic-ash plume reaching 3,700 meters high at Nevados de Chillán, an example of the above mentioned “higher than average energy levels.”

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