GeoLog

Geochemistry, Mineralogy, Petrology & Volcanology

Imaggeo on Mondays: An explosive cloud

Imaggeo on Mondays: An explosive cloud

One of the world’s most volcanically active regions is the Kamchatka Peninsula in eastern Russia. It is the subduction of the Pacific Plate under the Okhotsk microplate (belonging to the large North America Plate) which drives the volcanic and seismic hazard in this remote area. The surface expression of the subduction zone is the 2100 km long Kuril-Kamchatka volcanic arc: a chain of volcanic islands and mountains which form as a result of the sinking of a tectonic plate beneath another.  The arc extends from Hokkaido in Japan, across the Kamchatka Peninsula, through to the Commander Islands (Russia) to the Northwest. It is estimated that the Pacific Plate is moving towards the Okhotsk microplate at a rate of approximately 79mm per year, with variations in speed along the arc.

There are over 100 active volcanoes along the arc. Eruptions began during the late Pleistocene, some 126,000 years ago at a time when mammoths still roamed the vast northern frozen landscapes and the first modern humans walked the Earth.

Many of the volcanoes in the region continue to be active today. Amongst them is Karymsky volcano, the focus of this week’s Imaggeo on Mondays image. Towering in excess of 1500 m above sea level (a.s.l), the volcano is composed of layers of hardened lava and the deposits of scorching and fast moving clouds of volcanic debris knows as pyroclastic flows. You can see some careering down the flanks of the volcano in this image of the July 2004 eruption. The eruptive column is the result of a

“strong Vulcanian-type explosion, with the cloud quickly rising more than 1 km above the vent. The final height of the eruption cloud was approximately 3 km and in the image you can clearly see massive ballistic fallout from multiple hot avalanches on the volcanoes slopes,”

explains Alexander Belousov, a Senior Researcher at the Institute of Volcanology and Seismology in Russia and author of this week’s photograph.

 

USGS map of the Kuril-Kamchatka trench, showing earthquake locations and depth contours on downgoing slab. Credit: USGS, USGS summary of the 2013 Sea of Okhotsk earthquake, via Wikimedia Commons.

USGS map of the Kuril-Kamchatka trench, showing earthquake locations and depth contours on downgoing slab. Credit: USGS, USGS summary of the 2013 Sea of Okhotsk earthquake, via Wikimedia Commons.

If you pre-register for the 2015 General Assembly (Vienna, 12 – 17 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Imaggeo on Mondays: A Patagonia landscape dominated by volcanoes

Patagonia Landscape. Credit: Lucien von Gunten (distributed via imaggeo.egu.eu)

Patagonia Landscape. Credit: Lucien von Gunten (distributed via imaggeo.egu.eu)

Imagine a torrent of hot and cold water, laden with rock fragments, ash and other debris hurtling down a river valley: this is a lahar. A by-product of eruptions of tall, steep-sided stratovolcanoes, lahars, are often triggered by the quick melting of snow caps and glaciers atop high volcanic peaks.

The history of the Ibañes River and its valley, in southern Chile, are dominated by their proximity to Hudson volcano (or Cerro Hudson, as it is known locally). Located in the Andean Southern Volcanic Zone, the volcano has an unsettling history of at least 12 eruptions in the last 11,000 years. That equates to a major eruption every 3,800 years or so! The volcano has a circular caldera, home to a small glacier and is neighboured by the larger Huemules glacier.

One of the most significant eruptions occurred in 1991. It is thought to be one of the largest eruptions, by volume, of the 20th Century. At its peak, the eruption produced an ash plume thought to be in excess of 17km high, with ash being deposited as far away as the Falkland Islands. The initial eruptive phase was highly explosive. Known as phreatomagmatic eruption, hot and gas rich magma mixed with ice and water from the glacier on the summit of Mt. Hudson. As the eruption progressed, a period of sustained melting of both the caldera glacier and Huemules glacier began. The result of this was a 12 hour period of persistent lahar generation, with volcanic debris laden torrents racing down the Ibañes valley and its neighbours.

Fast forward to 2009 and the effects of the eruption of 1991 are still visible in the Patagonian Landscape. Lucien von Gunten photographed the inhospitable ‘Bosque Muerto’ (Dead Forest), in the Ibañes valley. The accumulation of the lahar deposits and the ash fall from the eruptive column clogged up the Ibañes river and valley killing a large proportion of the local flora and fauna. The ‘Bosque Muerto’ remains a stark reminder of the devastating effects of the 1991 eruption.

Reference

David J. Kratzmann, Steven N. Carey, Julie Fero, Roberto A. Scasso, Jose-Antonio Naranjo, Simulations of tephra dispersal from the 1991 explosive eruptions of Hudson volcano, Chile, Journal of Volcanology and Geothermal Research, Volume 190, Issues 3–4, 20 February 2010, Pages 337-352

 

If you pre-register for the 2015 General Assembly (Vienna, 12 – 17 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

The ethics of mining

This guest blog post is brought to you by Nick Arndt, Professor at ISTerre and convenor of the the Great Debate at last year’s General Assembly, Metals in our backyard: to mine or not to mine. During the Great Debate the issue of whether the environment impact of mining outweighs the benefits vs. domestic metal production was questioned. With Europe currently importing between 60-100% of the metals that are essential for modern society, this posts explores how realistic it is to advocate for no mining in our own backyards.

Two years ago, in response to massive demonstrations on the streets of Bucharest, the Romania government reversed its decision to allow mining of the Rosia Montana gold deposit. Fierce discussion currently surrounds the Pebble deposit in Alaska, the fifth largest unmined copper deposit. Last summer, protesters derailed mineral exploration in the Rouez region, the first exploration authorized in France for 20 years. In all cases, the activists argued that the environmental risks were so great that mining was unacceptable. The slogan of the French protesters was:

“no mines!!! neither in Rouez, nor anywhere”.

When the Rouez activists were asked where the metals needed for modern society should come from, many answered that improved recycling and substitution would provide the solution. If only this were true! Recycling will indeed provide an increasing proportion of our metals in the future, but for decades to come, new supplies of metals and other mineral products will be required. The vast infrastructure of wind turbines and solar panels needed for a low-carbon society will consume huge amounts of mineral products, not only the well-publicized rare earths and other critical elements, but also enormous quantities of steel, aluminium, concrete and sand. All these materials will be locked up for the 20-30 year lifetime of the structures and will not be available for recycling.

Anti-mining march Auckland New Zealand. Credit: Greg Presland (distributed via Wikimedia Commons)

Anti-mining march Auckland New Zealand. Credit: Greg Presland (distributed via Wikimedia Commons)

To organize their demonstrations, the Rouez and Bucharest activists used cell phones containing numerous rare metals, including cobalt-tantalum that probably came from war-torn central Africa. Some of the titanium might have come from a mine in Norway, and some copper from Poland, but the other metals were imported from outside Europe

The main reason why oil prices have plunged in the past three months is the recent availability of large sources of gas and oil from shale in the USA. While the low prices will have a negative medium-term impact on movements to wean society from fossil fuels, in the short term they may provide a sorely needed boost to struggling European economies. France is in a peculiar position – it has been at the forefront of the movement to ban fracking and has prohibited even the exploration for non-conventional hydrocarbons on its territories, but its feeble economy will benefit from the low energy costs brought about by the availability of American shale-derived oil and gas.

Other Rouez activists recognized that new sources of metals were necessary, but they were adamant that the mining should be done in a manner that caused minimal environmental damage … and preferably far, far away from where they lived. While some metals can be imported to Europe from countries with stable and competent governments like Canada and Australia, most come from Africa, Asia and South America where governments are commonly too weak, too corrupt, or too poor to ensure that mining is done properly. The concerned citizens of Europe and other rich countries prefer that people in other regions put up with the nuisance associated with mining, and if this means that mining is done in places where the operation cannot be done properly, so be it.

The locavore movement argues that we should consume only what is produced within a short distance from where we live. The principle is normally applied to food, and is based on sound principles. Local consumption provides employment to local people and reduces ‘food miles’ – the distance from producers to consumers. But aren’t these ideas equally valid for metals? Is it reasonable and logical to shun green beans from Kenya while consuming copper from the Congo? The Aitik mine illustrates that metals can be produced correctly and efficiently in Europe. This mine, which is located in the far north of Sweden and respects stringent Swedish social and environmental norms, efficiently exploits ore containing only 0.27% Cu, far below the global average.

Rather than adopting the dubious stance that others should bear the burden of supplying the metals needed for European society, is it not more principled to argue that mining should done correctly, and in our own backyard?

By Nick Arndt, Professor at ISTerre & current GMPV Division President

 

Imaggeo on Mondays: Artists’ Paint Pots

Many artists draw inspiration from nature and it’s not surprising when faced with landscapes which are as beautiful as the one featured in this week’s Imaggeo on Mondays post. Josep Miquel Ubalde Bauló writes about the origin of the colourful mud pots and bobby-socks trees!

Artists' Paintpots in Yellowstone National Park Credit: Josep Miquel Ubalde Bauló (distributed via imaggeo.egu.eu)

Artists’ Paintpots in Yellowstone National Park. Credit: Josep Miquel Ubalde Bauló (distributed via imaggeo.egu.eu)

This picture corresponds to The Artist Paint Pots, found in in Yellowstone, the first National Park of the world. Yellowstone is one of the most geologically dynamic areas on Earth. A huge underlying magma body releases enormous amounts of heat , which feed more than 10000 hydrothermal features (geysers, hot springs, mudpots, fumaroles), approximately half of all those found in the world.

The Artist Paint Pots is a small geothermal area, which was named after the pastel multicoloured mud pots. Much of the water in these mud pots is near boiling (85 ºC), meaning it is is difficult for life to thrive in them . Only some cyanobacteria and algae can live under these extreme conditions, and they are responsible for the beautiful colours in the mud pots.

The mud pots are acidic thermal features with a limited water supply. For their formation they require sulphite-reducing bacteria, which use hydrogen sulphide for energy, giving sulphuric acid as a waste product. The acidic water slowly dissolves the surrounding rocks, forming fine particles of silica and clay. This viscous clay-water mixture creates a muddy area, with the hot mud boiling and gas bubbling at the surface. The paint pots are coloured mud pots, which range from pink to bright red to purple, due to the iron oxides, potassium, and magnesium in the soil. The reason for the colours in the mud pots is a lack of sulphur. When sulphur is present, it reacts with iron oxides forming pyrite, which is grey.

In this area you can observe some groups of standing-dead trees. Whilst some of them burned in the fires of 1988 (during an unusually dry summer), others have been killed by the runoff from nearby thermal features, which flooded the area around the trees. Minerals in the water plugged the base of the trees and killed them, leaving their bases white. Those trees are known as bobby-socks trees.

By Josep Miquel Ubalde Bauló, Soil Scientist, Miguel Torres Winery

If you pre-register for the 2015 General Assembly (Vienna, 12 – 17 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly!  These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

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