olelog

If you have been near a smoking volcano or solfatara you may have experienced the foul odour of rotten eggs, which comes from the hydrogen sulphide that occurs in volcanic gases.

Huaynaputina (Quechua: "New Volcano") is a stratovolcano located in a volcanic upland in southern Peru. The volcano has also been variously known as Omate, Quinistaquillas, Chiquimote, and Chequepuquina. The volcano does not have an identifiable mountain profile, but instead has the form of a large complex 2.5 km diameter explosion crater with a maximum elevation of 4,800 m above sea level and edifice height of no more than 500 m. On 19 February 1600 it exploded catastrophically, in the largest volcanic explosion in South America in historic times. The eruption caused substantial damage to the major cities of Arequipa and Moquengua. It blanketed nearby villages with glowing rock and ash, and killed some 1,500 people.

The eruption is known to have put a large amount of sulphur into the atmosphere, and tree ring studies show that 1601 was a cold year. Sulphur reacts with water in the air to form droplets of sulphuric acid, which cool the planet by reducing the amount of sunlight reaching the Earth's surface. But the droplets soon fall back to Earth, so the cooling effects last only a year or so. In the Northern Hemisphere 1601 was the coldest year in six centuries. In Greenland the sulphuric acid spike was larger than that from Krakatau (1883). Regional agricultural economies took 150 years to fully recover. According to a new study of contemporary records the eruption had a global impact on human society. In Russia 1601-1603 brought the worst famine in the country's history, leading to the overthrow of the reigning tsar. Records from Switzerland, Latvia and Estonia record exceptionally cold winters in 1600-1602. In France, the 1601 wine harvest was late, and wine production collapsed in Germany and colonial Peru. In China, peach trees bloomed late, and Lake Suwa in Japan had one of its earliest freezing dates in 500 years.

"The volcano that changed the world" - Ken Verosub and his coauthor, student Jake Lippman, explore the effects the 1600 Huaynaputina eruption had on the global agricultural economy. Their work appears in the April 11th issue of American Geophysical Union newsletter EOS.

* http://www.eurekalert.org/pub_releases/2008-04/uoc--1ec042308.php
* http://www.physorg.com/news128177951.html
* http://www.scientificblogging.com/news_releases/the_climate_disruption_from_the_huaynaputina_eruption
* http://en.wikipedia.org/wiki/Huaynaputina
* http://www.nature.com/news/2008/080411/full/news.2008.747.html
* http://www.nature.com/nature/journal/v393/n6684/abs/393455a0.html

Much has been written about the impact from volcanic eruptions on climate change (cooling) and sea level changes. Less has been said about the impact from global warming and sea level rise on volcanism.

Sea level rise can reactivate volcanoes situated near sea level. Alaska's Pavlof volcano erupts every winter when (local) sea levels are higher - well just about 30 centimetres. Thirteen of sixteen magmatic eruptions of Pavlof Volcano in nine of the years from 1973 to 1998 have occurred between 9 September and 29 December. A significant correlation exists between the eruptions and yearly nontidal variations in sea level and may result from ocean loading. (See this abstract). The melting of polar ice sheets from global warming and the resulting stress placed on the earth's crust from rising sea levels will cause more magma and increase volcanic eruptions on a global scale in the years to come.

Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland in Reykjavik calculated how shrinkage of the Icelandic ice cap Vatnajökull affects what is happening below ground. Their findings will shortly be published in Geophysical Research Letters.

Pagli, C., and F. Sigmundsson (2008), Will present day glacier retreat increase volcanic activity? Stress induced by recent glacier retreat and its effect on magmatism at the Vatnajokull ice cap, Iceland, Geophys. Res. Lett., doi:10.1029/2008GL033510, in press.

When ice disappears, the added weight it forced upon the crust below it disappears as well. As a result this is increasing the rate at which the rocks under the ice sheet melt into magma. Iceland is home to several active volcanoes that exist underneath the ice, including Gjàlp, home of the last big eruption in 1996, and 58 years earlier in 1938. But according to Pagli and Sigmundsson the extra magma produced over the past century and more could reduce that time down to a gap of 30 years between each eruption. Volcanoes in Antarctica and Alaska will be at risk of similar increased volcanic activity. The shifting stresses could even cause eruptions in unexpected places.

And now that I am talking about Icelandic volcanoes - according to Iceland Review Online a giant volcano has recently been discovered off Reykjanes peninsula, Southwest Iceland, almost as large as the peninsula itself, and expected to erupt at any time. In the centre of the volcano there is a caldera measuring ten kilometres in diameter.

Since the volcano is at a depth of 1,500 metres eruptions would not have any effect on Iceland, except perhaps causing earthquakes (and tsunamis?). The volcano’s discovery is considered significant because it was believed it couldn’t exist in that area. Such large volcanoes are not supposed to be located on oceanic ridges. They are always drifting apart and that prevents a volcano from being created, so the volcano’s existence really came as a surprise.

• http://www.dailygalaxy.com/my_weblog/2008/04/will-a-warmer-w.html#more
• http://environment.newscientist.com/channel/earth/mg19826515.100-melting-ice-caps-may-trigger-more-volcanic-eruptions.html
• http://www.abc.net.au/news/stories/2007/09/14/2033161.htm?section=justin
• http://environment.newscientist.com/channel/earth/climate-change/mg19626324.600-volcanoes-give-sea-level-a-temporary-boost.html
• http://www.abc.net.au/science/news/stories/2005/1494475.htm

About 700 people were evacuated as the Llaima volcano erupted Wednesday, 2 January 2008, in southern Chile, rocking the area with explosions and spewing lava and ash. So far the 3,125 metres high Llaima, one of the most active among some 60 active volcanos in Chile, has not had a major blast since 1994, but last erupted in May 2007. Llaima Volcano is one of the largest and most active volcanoes in Chile, it has erupted some 60 times in recorded history. It is situated 82 km northeast of Temuco and 663 km southeast of Santiago, within the borders of Conguillío National Park. Llaima is a Mapuche word meaning "Blood Veins".

The subduction zone along the South American west coast is with its length of 7,400 km the longest subduction zone and deep sea trench in the world. The subduction has given rise to the Andes. Here three different plates are being subducted beneath South America - the Cocos Plate, the Nazca Plate and the Antarctic Plate - with different velocities along the boundary with the South American Plate. It does therefor not, as one otherwise might have expected, form one long continental volcanic arc. The Andes has three volcanic zones marked a, b and c on the map. Active volcanic centres correlate with regions where the dip of the subduction zone is about 30°. Where the dip is shallow, 5-10°, there are no active volcanoes.

The (second) map shows some of the major active volcanoes south of the Chilean capital Santiago, including the Llaima volcano.

• http://www.terradaily.com/reports/Chiles_Llaima_volcano_erupts_in_smoke_and_flames_999.html
• http://news.yahoo.com/s/ap/20080102/ap_on_sc/chile_volcano
• http://www.foxnews.com/story/0,2933,319417,00.html
• http://en.wikipedia.org/wiki/Llaima

Scientic American runs a video showing the eruption at
http://www.sciam.com/video.cfm?id=405EC576-D108-E548-5C4B7DF634F69C0A

My latest post was about hotspot volcanoes (Hawaii) and isotopes (helium), so let us move on from there. In 2005, erupted into public awareness in the made-for-TV movie Supervolcano, and suddenly the media were full of scaring stories about this hotspot supervolcano. Probably it will last another 1 million to 2 million years before a new supervolcano is born to the Northeast of the Yellowstone caldera. Nevertheless it presents a significant potential hazard to humankind. It is no surprise, then, that scientists are eager to uncover clues about Yellowstone’s past that could aid in predicting the volcano’s future behaviour. Last week Geotimes brought an article titled Yellowstone and Heise: Supervolcanoes That Lighten Up. If you have not heard of Heise, it is the supervolcano that erupted a few hundred thousand years before the event that produced the Yellowstone Caldera. It is located about 50 miles Southwest of Yellowstone.

Three massive explosive eruptions occurred at Yellowstone over the past 2.1 million years with a recurrence interval of about 600,000 to 800,000 years. Oxygen isotope signatures of individual crystals within volcanic rocks can help fingerprint the different magma sources. Oxygen atoms possess eight protons in their nucleus, but they may have eight, nine or 10 neutrons, yielding three possible oxygen isotopes: oxygen-16, oxygen-17 and oxygen-18. (See also my post on Climate Change and Scientific Language for more on oxygen isotopes) Magma formed from melting of the mantle or continental crust contains more oxygen-18 than shallow magma formed from melting of hydrothermally altered crust.

A few words on hydrothermal circulation (“hydro” meaning water and “thermal” meaning heat). Hydrothermal systems form when snow and rain water accumulate in pools and penetrate through fractures in the caldera, enabling the surface waters to circulate and become heated by hot, underlying magma. Snow and rain water contain “light” oxygen isotopes and when in contact with “normal,” accumulated volcanic rocks within the depressed caldera, oxygen from the water mixes with oxygen from the rocks. This results in oxygen-18-lowered rock and oxygen-18-enriched water. Hydrothermal waters can only travel up to a few kilometres below the surface, at which point any empty spaces in the rock are sealed off due to pressure. Thus, the light oxygen isotope fingerprint enables geologists to identify a near-surface environment as the source for these light magmas.

Being a hotspot volcano geologists originally thought that Yellowstone magmas were solely derived from continental crust and mantle material with heavier oxygen isotope signatures. Many volcanic fields of the Snake River Plain, including the Yellowstone Plateau, however contain magmas conspicuously low in the heavy oxygen-18 isotopes, giving the magmas so-called “light” signatures.

The authors suspect a cannibalisation process, where large swaths of hydrothermally altered volcanic material were remelted to produce “light” magmas. The sheer volume of the light magmas, some greater than 1,800 cubic kilometres, made them however ask themselves if it possible to generate such large volumes of oxygen-18-depleted magma by shallow remelting?

A positive note is that both Heise and Yellowstone produced three normal caldera-forming magmas and a series of light “cannibalised” post-caldera magmas. The final stage of volcanism in each volcanic field is marked by light magma eruptions.

Said with more scientific terms: “The occurrence of low ∂¹⁸O magmas at Heise and Yellowstone hallmarks a mature stage of individual volcanic cycles in each caldera complex. Sudden shifts in ∂¹⁸O of silicic magmas erupted from the same nested caldera complexes argue against any inheritance of the low ∂¹⁸O signature from mantle or crustal sources.”

If Heise is any indication, this could mean that the Yellowstone drama has entered its final act, but the volcano could exit with a climactic “big bang.” It is not known if the fourth caldera-forming eruption of Yellowstone will be analogous to the fourth and final caldera-forming light magma of Heise. Alternatively — and more likely — the Yellowstone supervolcano is geologically dead?


* http://www.geotimes.org/nov07/article.html?id=feature_yellowstone.html
* http://geology.geoscienceworld.org/cgi/content/abstract/35/11/1019
* http://gsa.confex.com/gsa/2007AM/finalprogram/abstract_132139.htm
* http://volcanoes.usgs.gov/yvo/
* http://volcanoes.usgs.gov/yvo/2006/uplift.html
* http://www.60secondscience.com/archive/earth-science/supervolcanic-time-bomb-aka-ye.php


See also my post on Yellowstone Super-volcano - http://my.opera.com/nielsol/blog/show.dml/164981

The Andes has three volcanic zones. The Central Volcanic Zone of the Andes is located between latitudes 14° and 28°S of the Andean cordillera. The area has around 50 active or potentially active volcanoes, spread along a 1500 km-long volcanic arc. These volcanic structures mostly rise to between 4000 and 7000 m, are very remote with abrupt slopes and are often cloaked in snow. Few studies have been made on them as such conditions make field surveying extremely difficult. In fact so little is known about this area that the majority of the volcanoes have never been described, and in a few cases, have not even been named.

A team of researchers has now focused special attention on the Lastarria-Cordon del Azufre volcanic complex. With a surface area of 1600 km², it is situated in the central Andes Cordillera at the border between Argentina and Chile near Antofagasta.

Deformation (connected with volcanic activity) in the area is monitored by satellite, using radar interferometry. This measurement method is based on the superimposition of two satellite radar images of the same geographical area taken at different times. The resulting differential signal between the images, termed the interferogram, provides a way of detecting possible deformation of the earth crust.

• http://www.eurekalert.org/pub_releases/2007-10/idrp-smf100507.php
  
• http://www.physorg.com/news110861686.html
  
• http://www.associatedcontent.com/article/405570/new_developed_satellite_methods_will.html
  
• http://volcano.space.edu/cvz/intro.html
  

I would like to point out that the picture used to illustrate the associatedcontent article is NOT from the Central Volcanic Zone, but from the Southern Chile Zone (South of Santiago), namely the Osorno volcano near Puerto Montt in Chile. I hereby forgive the author for having used the image without asking my permission. At least it is provided with credit and link to my page, including mention of my copyright.