Tungurahua

Tungurahua was built in three parts. Two older parts fell down long ago.

The volcano you see today is the newest part.

IG-EPN explains that Tungurahua grew as three volcanoes, one after another: Tungurahua I, II and III. The first two each had a side collapse, about 30,000 and 3,000 years ago, and their rock avalanches spread into the valleys of the Chambo and Patate rivers.

The volcano we see today, Tungurahua III, began about 2,300 years ago with a great lava flow. Since the year 1300, it has erupted at least once every century.

IG-EPN, citing Hall et al. (1999): three successive edifices, Tungurahua I, II and III; the first two suffered sector collapses at 30 and 3 ka, whose avalanche deposits crop out in the Chambo and Patate valleys. Tungurahua III began with the great Las Juntas lava flow about 2,300 years ago.

Since AD 1300 it has produced pyroclastic flows, ash falls, lava flows and lahars at least once per century (Le Pennec et al., 2008).

Tungurahua erupted on and off from 1999 to 2016. Ash fell far away.

Now it is quiet, but scientists keep watching.

Tungurahua's last eruptive period began in 1999 and lasted until 2016, with explosions and clouds of gas and ash. In July and August 2006 came two big explosive eruptions, and the ash spread far enough to reach the city of Guayaquil.

The last eruption, in February 2016, lasted 19 days. After two quiet years, in 2018 the volcano stopped being called 'erupting' and is now considered 'active'. IG-EPN says its earthquakes are now few and it gives off no gas.

IG-EPN: the eruptive period began in 1999 with subcontinuous Strombolian and Vulcanian explosions and gas and ash emission; in July and August 2006 two large explosive eruptions sent pyroclastic flows mainly down the western and southwestern flanks, with regional ashfall reaching Guayaquil. Later activity came in episodes of days to weeks, with pauses of up to three months.

The last eruption (February 2016) lasted 19 days, ejected about 1.5 million m3 of material (VEI 2) and ended the 1999 period; since 2018 Tungurahua is classed as 'active' rather than 'erupting', with low seismicity and no gas emission.

Tungurahua is part of a big national park. Mountain tapirs and spectacled bears live there.

The park has hundreds of lakes.

UNESCO says Sangay National Park, which includes Tungurahua, holds the whole range of Ecuador's ecosystems, from glaciers and volcanoes to cloud forest and Amazon rainforest.

The park is home to threatened animals such as the mountain tapir and the spectacled bear, and to the Andean condor. It has 327 lakes and one of the largest areas of páramo, a high mountain grassland, in Ecuador.

UNESCO: Sangay National Park (271,925 ha; inscribed 1983) spans 900 to 5,319 m and the entire spectrum of Ecuador's ecosystems: glacial and volcanic, cloud forest, Amazon rainforest, wetlands and lakes; its three volcanoes include Tungurahua and Sangay, one of the more active volcanoes in the world.

It shelters threatened species such as the mountain tapir and spectacled bear and emblematic species such as the Andean condor, 327 lakes covering 31.5 km2, and one of Ecuador's largest areas of páramo.

Volcanoes can be dangerous. Always listen to the people in charge.

Know your family's plan for leaving quickly.

The CDC says to follow the advice of local officials about volcanoes, including when and how to leave an area or take shelter. Families should make a plan both for leaving and for staying inside, and make sure everyone understands it.

IG-EPN watches Tungurahua with instruments that measure earthquakes, ground movement, gases and hot springs.

CDC eruption preparedness: follow local officials on preparation, evacuation or sheltering in place; make evacuation and shelter plans and review them with everyone in the household.

IG-EPN monitors seismicity, deformation, degassing, hot springs and temperature; it notes that lahars in past eruptions descended mainly by certain ravines and that pyroclastic flows in 2006 used the northern and western ravines.