South American volcano shows potential signs of instability, research shows

Tungurahua volcano in Ecuador – known locally as “The Black Giant” – is displaying the hallmarks of localised flank instability, which could result in a large landslide.

New research, led by Dr James Hickey from the Camborne School of Mines, shows significant rapid deformation on the western flank occurred in 2015.

The researchers believe that the driving force causing this deformation could possibly lead to an increased risk of the flank becoming unstable, potentially causing damage to the surrounding local area.

The research recommends the volcano should be closely monitored to watch for stronger signs that the volcano could be growing unstable.

The study is published in the journal Earth & Planetary Science Letters.

Dr Hickey, who is based at the University of Exeter’s Penryn Campus, Cornwall, said: “Using satellite data we observed very rapid deformation of Tungurahua’s west flank in 2015, which our research suggests was caused by imbalances between magma being supplied and magma being erupted”.

Tungurahua volcano has a history of flank collapse, and has been frequently active since 1999. The activity in 1999 led to the evacuation of 25,000 people from nearby communities. 

A previous eruption of Tungurahua, around 3,000 years ago, caused a prior, partial collapse of the west flank of the volcanic cone.

This collapse led to a wide-spread debris avalanche of moving rock, soil, snow and water that covered 80 square kilometres – the equivalent of more than 11,000 football fields.

Since then, the volcano has steadily been rebuilt over time, peaking with a steep-sided cone more than 5000 m in height.

However, the new west flank, above the site of the 3000 year old collapse, has shown repeated signs of rapid deformation while the other flanks remain stable.

The new research has shown that this deformation can be explained by shallow, temporary magma storage beneath the west flank. If this magma supply is continued, the sheer volume can cause stress to accumulate within the volcanic cone – and so promote new instability of the west flank.

Dr Hickey added: “Magma supply is one of a number of factors that can cause or contribute to volcanic flank instability, so while there is a risk of possible flank collapse, the uncertainty of these natural systems also means it could remain stable. However, it’s definitely one to keep an eye on in the future.”

Rapid localized flank inflation and implications for potential slope instability at Tungurahua volcano, Ecuador is published in the journal Earth & Planetary Science Letters.