Category Archives: Climate

Today in Geological History; Feb 19th – Huaynaputina 1600

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Today 416 years ago South America experienced its most explosive eruption in historical times. The unassuming Huaynaputina volcano sits in southern Peru just 26 km of Ubinas, the countries most active volcano. Unlike its 5672 m neighbour, Huaynaputina has no distinct topographic elevation and lays inside a 2.5 km crater leading many to believe it was just a mountain caused by other forces. Laying in the Andean Volcanic Belt where the Nazca Plate subducts under the western edge of the South American Plate it is situated on the rim of the Rio Tambo canyon further camouflaging it to the untrained eye.

The sleeping giants last eruption was in February 1600. Reaching an impressive VEI 6, it was the biggest eruption of the past 2000 years.

Details of the eruption were captured beautifully by Fray Antonio Vazquez de Espinosa a Spanish monk travelling through Central and South America at the time. Days before the eruption booming noises were heard from the vicinity and steam was seen seeping from the volcano. Locals began to panic, preparing young girls for sacrifice to appease Supay the god of death who people believed was angry at them and causing the mountains behaviour. February 15th marked a strong increase in activity with tremors becoming stronger and more frequent, many began to leave the area fearing something bigger was coming.

At roughly 5 P.M. on February 19th, Huaynaputina erupted violently catapulting ash high in to the stratosphere. Pyroclastic flows sped down all sides of the volcano, to the south mixing with the waters of the Rio Tambo river causing devastating lahars.  Within just 24 hours, Arequipa was covered with 25 centimetres (10 in) of ash. Ashfall was reported 250–500 kilometres (160–310 mi) away, throughout southern Peru and in what is now northern Chile and western Bolivia. It is thought that more than 1500 people were killed by the eruption its self although with little record of populations at the time the figure varies between sources. 10 villages were completely buried by ash and regional agricultural economies took 150 years to recover fully.

It was not just South America which was effected by the eruption. Ice cores recorded a spike in acidity at the time indicating a phenomenal amount of sulphur dioxide was released. Effects on the climate right around the Northern Hemisphere (Southern Hemispheric records are less complete), leading to 1601 being the coldest year in six centuries, leading to one of the worst famines ever recorded in Russia. In Estonia, Switzerland and Latvia, there were bitterly cold winters in 1600–1602 leading the deaths of hundreds; in 1601 in France, the wine harvest came late and in Germany production of wine collapsed completely. In Japan, Lake Suwa had one of its earliest freezings in 500 years and even China recorded peach trees blooming late.

An eruption of this scale in the populated Peru would be devastating so close watch is kept on Huaynaputina and its more active neighbours.

 

Figure 1; https://commons.wikimedia.org/wiki/File:Huaynaputina.jpg

Figure 2; https://volcanohotspot.wordpress.com/2015/04/12/volcanoes-of-peru-3-huaynaputina-catastrophe-in-1600/

 

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Tambora – Earth’s Last Super Eruption; 200 Years On

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Mount St Helens, Verusvius, Krakatoa; humanity has witnessed some pretty explosive eruptions that have changed how we view our planet. However these have been nothing compared to the large caldera forming, ignimbrite eruptions or flood basalts of the past. The closest humans have seen to the elusive ‘super eruption’ occurred 200 years ago on the Indonesian island of Sumbawa, and it changed our view on volcanics for all time.

Up until the early 1800’s the mountain of Tambora, although towering roughly 14,000 ft over the surrounding area, seemed a rather nonthreatening feature of the landscape. No eruptions for hundreds of years meant few locals even knew it was of volcanic origins. The British East India Company had not long laid claim to many of the Indonesian islands when this began to change around 1812. The foreign residents knew little of the Earth’s more violent activity and even natives paid little attention to an increase in seismicity and small phreatic eruptions and minor ash emissions.This is what made the events which began April 5th 1985 all the more deadly.

Cannon Fire

Figure 1. An artist impression of the eruption on April 5th.

Thomas Stanford Raffles was at the time the lieutenant governor of Java. Although of a political position he had a keen scientific mind and brought in zoologists and botanists to the islands as well as making his own observations and recordings. He was, in his own right,  one of the first true volcanologists, being the first to scale a volcano using a thermometer to measure differences from base to peak. On April 5th he was over 800 miles away from Tambora when things really began. At just after 7 pm as people settled down in to their evenings Tambora let out and immense roar. Raffles, like many, recorded hearing ‘cannon fire’, troops were even deployed from Djogjokata to seek out potential threat at sea. When ash began to lightly fall by the next morning Raffles sent out parties to find the source of the eruption. Klut, Merapi or Bromo were thought to be the most likely culprits being highly active and close enough to cover the area in ash, Tambora was not even considered. As the days went on and the ash fall waned so did the search and things settled down with the volcano momentarily. The initial eruption only last two hours and ash fall a few days. Sadly this did not last….

The Blast

It soon became apparent that the eruption on the 5th was purely Tambora clearing her throat and preparing for a much bigger song. On April 10th 3 epic blasts from areas near the summit sent material 40 km in to the sky, meeting to produce a spectacular eruption column. Eventually the three vents caused a huge collapse creating the 6-7 km wide caldera still visible today. Pyroclastic flows sped down the flanks destroying everything in their path. The flux of material pouring in to the Flores sea to the caused a tsunami that rapidly spread through the surrounding waters and islands with waves up to 6ft high. Within 3hrs the sky was invisible for miles, as far as West Java and South Sulawesi. The loud explosions were heard through to the next night showing little sign of easing for over 24hrs.

Figure 2. Path of the ash cloud. Most of the red area was in complete darkness while the eruption was persistent and for days after.

The eruption did not settle down until April 17th, with the summit completely obscured by an ash cloud untill the 23rd. Explosions although smaller, did not cease untill July 15th, and smoke emissions were still observed as late as August 23rd.

Figure 3. Out put of several major eruptions in recent history.

Tambora lost at least 2000 ft off its summit equating to it loosing nearly a third of its original height. It is believed to be the only VEI 7 eruption of our time (luckily for us!). The VEI index is a logarithmic scale meaning each level is ten times that of the previous. Based on eruption output the graph in figure 3 shows just how big this eruption was. Thanks to Pompeii, Versuvius’ 79 Ad eruption is probably one of the most famous eruptions but even this killer pales in magnitude compared to Tambora’s might! The explosion was 800 Mt (3.3×1012 MJ), four times the energy of Krakatoa and would make even an atomic bomb look like dropping a pebble in an ocean. Rafts of pumice up to 5 km across caused havoc on shipping lanes and even crossed the Indian ocean washing up on Calcutta 6 months after the eruption began. It is believed at leat 12,000 were directly killed by the eruption through pyroclastic flows. Add to this the tsunamis and devastation to the land which brought famine and disease bringing an estimate of 72,000 – 100,000 fatalities caused by the eruption.

Since the eruption, a violent diarrhoea has prevailed in Bima, Dompo, and Sang’ir, which has carried off a great number of people. It is supposed by the natives to have been caused by drinking water which has been impregnated with ashes; and horses have also died, in great numbers, from a similar complaint.

—Lt. Philips, ordered by Sir Stamford Raffles

But it was not just the local area which was effected by the blasts, Tambora brought on what is famously known as The Year Without a Summer. As well as pyroclastic material the eruption injected a massive amounts of sulphur dioxide and other volatiles not just in to the atmosphere but they were catapulted in to the stratosphere. This caused globe climate chaos for several years. The Northern Hemisphere got the brunt of the bizarre weather such as frost in June and some of the most spectacular coloured sunsets ever recorded.

Crops failed world wide and famine was riffe in many areas. It is believed the climate change brought on by Tambora attributed to 90,000 extra deaths over the years after the eruption. Although the weather had many negative effects it inspired many and was indirectly recorded in many notable artist such as Willam Turner and poetry like Lord Byron’s Darkness. Even literature was influenced as Mary Shelly’s backdrop to Frankenstein mirror the climate caused by Tambora.

“I had a dream, which was not all a dream at all
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space,
Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air;
Morn came and went–and came, and brought no day,
And men forgot their passions in the dread
Of this their desolation”
Lord Byron Darkness

When Krakatoa erupted in 1883 it was the first eruption to make world-wide news as the telegraph made it more accessible. Such technology was not available in 1815 so news of tragedy in Indonesia only travelled as fast as the best ship. Even for people who did know about the events no link was ever made to the weather conditions which plagued the world. Unlike Pompeii’s early discovery pushing it to the limelight, it was only in 2004 that archeologists found remains of villages buried deep under the deposits Although excavation still takes place in the area it is believed they have barely scratched the surface.

Remains of a Tamboran caught by the pryoclastic flow

Figure 4. Finding in 2004 if remains from a village destroyed by a pyroclastic flow.

We don’t know if or when Tambora will blow her top again, we don’t know if further eruptions from her or any other of the 150 volcanoes in Indonesia will erupt so violently or even worse. What we do know is that we live on a violent, dynamic planet which is beyond our control. We need to learn from eruptions of the past, and to read precursors to such events to limit their effects on humanity so we have a chance for surviving the next big one.

 

Figure 1. http://madmikesamerica.com/2011/09/terrified-farmers-flee-ahead-of-deadly-volcano-eruption/

Figure 2. http://commons.wikimedia.org/wiki/File:1815_Tambora_Sumbawa_explosion_path_large.jpg

Figure 3. http://legacy.earlham.edu/~ethribe/web/tambora.htm

Figure 4 http://www.pasthorizonspr.com/index.php/archives/11/2009/re-discovering-the-lost-kingdom-of-tambora

Today in Geological History – March 28th; El Chichón

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When you think about climate changing eruptions from the last few decades you mind usually automatically jumps to Pinatubo. However there was an eruption which was almost as climate altering just 9 years previous.

El Chichón sprang to life in the spring of 1982, with no confirmed eruptions since 1360, many had believed it was extinct. Laying in Southern Mexico between the Trans-Mexican Volcanic Belt and the Central American Volcanic Arc it is actually quite far from any other regularly active volcanoes. Seismicity began to increase in the region around El Chichón from early in 1980 through to the end of 1981 but no extra monitoring or investigation took place as the volcanic complex was not believed to be a threat.

This was proved wrong however on the 28th of March seismicity increased dramatically although locals failed to realise they were experience volcanic tremors not the earthquakes often felt in the region. At 23.22 that night an eruption has decimated the lava dome which had grown in VEI 5 Plinian eruption. This initial eruption only lasted a few hours but flung nearly half a cubic kilometer of dense rock at a terrifying rate. The area was quickly and erratically evacuated but as things settled down over the next few days, with only small vulcain or phreatic episodes near the main vent, people began to return home.

However El Chichón was far from finished clearing his throat and on Sunday April 4th a much larger eruption begun. It began with a huge pyroclastic flow which surged down the flanks at speeds in excess of 100 km p/h. The village of Francisco Leon was completely buried killing about 1000 people. A further two Plinian eruptions occurred later in the day causing an ash column towering over the landscape at over 29km high.

By the time things really calmed down roughly 2000 people had lost their lives and 9 villages had been devastated. The new crater spanned a kilometer wide and 300 meters deep, this has since filled with water creating a highly acidic crater lake as seen below.

The area around the complex was predominantly agricultural land and with over 24,000 square kilometers were covered in thick ash, many crop plantations were completely lost, making this Mexico’s most costly natural disaster of recent history.

It was not just Mexico however that felt the effects of the explosions. Seriously high levels of sulphur dioxide and other volatiles were sent in to the atmosphere. This coincided with the strongest El Niño phase recorded which lead to some suggesting it was caused by the eruption, however no scientific link was ever made. The combination of the two saw dramatic effects on climate world-wide.

El Chichon was a huge wake up call around the globe, showing us that we need to pay closer attention to signs our planet give us, no matter what our preconceptions. Ignorance that a volcano has not be active for a few hundred year lead to seismic warnings being ignored which in turn lead to the loss of lives.

It also shows that for all our worry about climate change and anthropogenic emissions, the Earth actually has the upper hand regardless of our efforts; one simple eruption at the right latitude can effect the world’s climate for years and there is little we can do about it…..

Figure 1. http://jennysmexico.blogspot.co.uk/2012/01/mexicos-volcanoes-mesoamerican.html

Figure 2. https://curiousmatters.wordpress.com/2014/05/23/curious-facts-31-of-the-strongest-volcanoes-known-to-man/

Figure 3. http://www.john-daly.com/soi-temp.htm