Category Archives: Volcano

Eruptions at Erta Ale volcano

Incredible footage of lava flows out of Erta Ale volcano in northeastern Ethiopia. Erta Ale is located in the Afar depression, a badland desert area that is part of the northern section of the East African Rift system. The volcano is one of only a few in the world with a constantly active lava lake.

Eruptions at Piton de la Fournaise volcano

Spectacular drone footage of the recent eruptions at Piton de la Fournaise volcano on Reunion Island.

Mega-plumes from volcanic eruptions on Io

500km high eruption plumes on Jupiter’s moon Io, the most volcanically active object ever discovered!

Io_eruption
Image source: New Horizons mission, NASA

Lateral Blast: The Mount St Helens eruption

Today is the 36th anniversary of the historic eruption of Mount St. Helens in Washington State, USA.

The May 18, 1980 eruption was a rare type of volcanic eruption known as a lateral blast. Most explosive volcanoes throw material upwards in an eruption; in the case of Mt. St. Helens the eruption occurred horizontally, releasing pent-up pressure inside the volcano. The eruption obliterated the entire north side of the volcano and resulted in the largest debris avalanche in recorded history.

eruption
An incredible series of images showing the explosive flank collapse in the eruption. Source: USGS

The 1980 Mt. St. Helens eruption played an extremely important role in improving our understanding of volcanic eruptions and the magma plumbing system beneath volcanoes. It was the first time pyroclastic flows – clouds of super hot gas, ash and rock that move at hundreds of miles per hour – were studied using modern scientific techniques. Even now, 36 years later, scientists are still publishing new and interesting insights gleamed from the 1980 and later eruptions.

Current_activity_USGS
The new central cone inside the older crater. Source: USGS

The volcano is still very much alive today. In recent decades a new volcanic cone has developed in the central crater. Thankfully, scientists from the United States Geological Survey (USGS) are keeping a close eye on the volcano and will hopefully provide warning if a new eruption is imminent.

See how Earth’s 1000+ active volcanoes were formed in this great national Geographic video.

 

More information:
[1] https://volcanoes.usgs.gov/volcanoes/st_helens
[2] https://pubs.usgs.gov/fs/2013/3014/fs2013-3014_text.pdf
[3] https://volcanoes.usgs.gov/observatories/cvo
The feature image at the top of the article was taken by astronaut Tim Peake from the International Space Station in 2016. Source Flickr

Living with volcanoes

Here’s a great video of volcanologist and Royal Society Fellow Steve Sparks talking to Jim Al-Khalili about how people live with volcanoes.

Review: Krakatoa – The day the world exploded

Krakatoa
In 1883 the Indonesian island volcano of Krakatoa erupted in one of the most violent volcanic eruptions ever witnessed by man. The eruption vaporised the island and its inhabitants, created a tsunami and resulted in over 36,000 deaths.

The explosion was so loud it was reported to have been heard 4,800 km away in Australia and India. This is the most distant sound that has ever been heard in recorded history.

In Krakatoa: The day the world exploded best selling author Simon Winchester provides a well researched, detailed account of this mega eruption.

A geologist by education and a journalist by profession, Winchester’s book is a beautiful marriage of both science and social history. The early chapters focus on the history of plate tectonics and the state of geological knowledge before the 1883 eruption. While the latter focus on the eruption itself and the societal impacts on the then Dutch East Indies.

In painstaking beautiful detail Winchester brings to life the events leading up to, during and after the disaster through eyewitness reports and ship’s logs.

Horrible was the view of that sombre and empty landscape, which
portrayed itself as a picture of total destruction rising from the sea.
T. H. Lindeman, Captain of The Loudon

What I love about this book is that it portrays the science of the eruption alongside the views and beliefs of the people who witnessed it. From those who thought it was the onset of Armageddon to the speechless ship’s crews on the Indian Ocean, no one had ever witnessed such a cataclysmic event.

So violent are the explosions that the ear-drums of over half
my crew have been shattered. My last thoughts are with my
dear wife. I am convinced that the Day of Judgement has come.

Captain Sampson of Norham Castle

The societal impact in the Dutch East Indies were profound. The eruption helped to trigger a wave of murderous anti-Western militancy among fundamentalist Muslims, one of the first outbreaks of Islamic-inspired killings anywhere.

Krakatoa provides an entirely new perspective on this fascinating and iconic event.

Double warning time for volcanic lahars

By Robert Jones

Real-time rainfall data can be used to potentially double warning times for rain-triggered lahars on the slopes of Tungurahua Volcano, compared existing ground-based detection methods.

Tungurahua volcano is located in the Eastern Cordillera of the Ecuadorian Andes and its current period of eruptive activity has been ongoing since 1999. This intermittent activity has resulted in the deposition of a lot of loose unconsolidated pyroclastic gravel, dust and ash on the slopes of the volcano.

A recent Tungurahua at night. Source: Dr. Carlos Costales Terán, Wikimedia Commons
A recent Tungurahua eruption at night.
Source: Dr. Carlos Costales Terán, Wikimedia Commons

During heavy rainfall, for which this region is renown, this loose material gets mixed into the rain water flowing off the volcano and results in extremely dangerous rain-triggered lahars, or volcanic mudflows. Think flash floods and giant rivers of mud and rock rolled into one.

The city of Baños lies approximately 8 km north of the summit of the volcano and is a very popular tourist destination, with its population increasing from approximately 18,000 to around 50,000 during holiday periods. The primary road linking Baños with the Pan-American Highway and other provincial cities crosses several lahar-prone drainages of Tungurahua and these flows pose a significant risk to infrastructure within these valleys.

Rain-triggered lahars have not caused any fatalities at Tungurahua but cars have been buried, road crossings inundated and the El Salado Baths (a popular visitor attraction) have nearly been inundated by flows in previous years.

An incoming lahar from mount Tungurahua. Source: IGEPN
An incoming lahar from mount Tungurahua.
Source: IGEPN

The volcano is monitored from the Tungurahua Volcano Observatory (OVT), operated by the Instituto Geofisico, Escuela Politécnica Nacional (IGEPN). The primary methods of lahar monitoring are detection by Acoustic Flow Monitors (AFMs), which measure ground vibration as the flow passes and also flow identification by a community-based monitoring system consisting of a network of volunteers known as Vigias.

Analysis of both the rainfall and lahar record between March 2012 and June 2013 indicated that peak rainfall intensity can be a key indicator of a potential lahar occurrence. The peak rainfall intensity during a particularly rainy period is used along with previous knowledge of the amount of moisture already in the landscape to estimate the probability that a lahar will exceed a pre-defined flow size. This method was tested using the July-December 2013 lahar and rainfall records and not only did our probabilities effectively predict the occurrence of lahars, but peak estimated lahar probability was consistently reached prior to lahar detection by the Acoustic Flow Monitor network. This probabilistic analysis produced an average of 24 additional minutes of warning time during the test-period.

Read the full paper at: http://link.springer.com/article/10.1007%2Fs00445-015-0946-7

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Robert Jones is a PhD research student in the School of Earth and Environment at the University of Leeds.

Here’s an example from Ubinas volcano in neighbouring Peru, of the force and destructive power of lahars.