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Volcanoes to blame for Cretaceous ocean anoxic event 11 February 2010

Posted by admin in climate, current research.
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Research published in a letter in Nature Geoscience: around 94.5 million years ago volcanism released large volumes of sulphur into the atmosphere which triggered huge phytoplankton blooms, which in turn deprived the oceans of oxygen and triggered extensive marine extinctions. The abstract tells it like this:

During the Cretaceous period (~145–65 million years ago), there were several periods of global ocean anoxia, each lasting less than one million years. These events, known as ocean anoxic events, were marked by significant increases in organic carbon burial, and are generally attributed to increased primary productivity in surface waters. The details underpinning the initiation, maintenance and termination of these events, however, remain equivocal. Here we present sulphur isotope data spanning the Ocean Anoxic Event 2 (about 94.5 million years ago) from sedimentary rocks in Colorado that were formed in the Western Interior Seaway; this seaway ran north–south, splitting North America during the Cretaceous. Sulphate levels increased rapidly from relatively low background levels at the onset of the event, most likely from the release of sulphur by massive volcanism, and fell during the anoxic event. We infer that the input of sulphate facilitated increased carbon remineralization, which enhanced nutrient recycling and increased global primary productivity, eventually resulting in widespread ocean anoxia. Our scenario indicates that Ocean Anoxic Event 2 may have persisted until sulphate levels were stabilized by the formation and burial of the sulphur mineral pyrite, which returned primary productivity to background levels. We suggest that fluctuations in sulphate levels may have regulated the marine carbon cycle during past periods of low oceanic sulphate concentration.

And that is why geoengineering the climate with artificial volcanoes is a really bad idea: ‘Like the mid-Cretaceous ocean, most modern lakes are poor in sulphate, so it’s possible that geoengineering the climate could trigger blooms and ultimately anoxia in some lakes’ says researcher Matthew Hurtgen of Northwestern University. ‘We hack the climate at our peril’, warns New Scientist. ‘Volcanoes spewed so much sulphate into the atmosphere 94 million years ago that the oceans were starved of oxygen and 27 per cent of marine genera went extinct. Geoengineering our climate could inflict a similar fate on some lakes’. Such is the climate change dilemma: in trying to avoid (for example) climate-induced tectonic-volcanic geo-apocalyptic mega-mayhem we may cause geoengineering-induced volcanic-toxic extinction-anoxic mega-mayhem instead. Agh.

  • Derek D. Adams, Matthew T. Hurtgen & Bradley B. Sageman, ‘Volcanic triggering of a biogeochemical cascade during Oceanic Anoxic Event 2’, Nature Geoscience, 31 January 2010 [doi:10.1038/ngeo743]. Abstract.

(There’s more on volcanism triggering the Cretaceous anoxic events in Nature, 17 July 2008, and Ole Nielsen has a great blog post: Late Cretaceous Anoxic Event.)

The Volcanism Blog

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New website for the International Volcanic Health Hazard Network 18 January 2010

Posted by admin in natural hazards.
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The International Volcanic Health Hazard Network (IVHHN) does excellent work with the collection of data and the communication of information in the relatively new field of volcanic health hazard research. The IVHHN describes its aims as follows:

  • To promote the expansion of the newly emerging field of volcanic health hazard research.
  • To continue existing collaborations and develop new collaborative links between the multidisciplinary international partner organizations.
  • To produce and widely disseminate protocols and volcanic health hazard information to volcano observatories, scientists, governments, emergency managers, health practitioners and the general public.
  • To encourage collection of geologic and medical data to evaluate health hazards.
  • The formation of databases of well-characterized ash and gas samples and literature from volcanoes world-wide, for use by the Network and other workers.

The IVHHN website has just been re-launched, and offers easy access to information and resources about the Network, including two invaluable new pamphlets available in a range of languages: The Health Hazards of Volcanic Ash: A Guide for the Public, and Guidelines on Preparedness Before, During and After an Ashfall.

For more information visit the new IVHHN website: International Volcanic Health Hazard Network.

The Volcanism Blog

‘Compelling evidence’ discovered of previously unknown volcanic eruption, 1809 AD 31 October 2009

Posted by admin in climate.
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News that a U.S./French team of chemists claim to have found ‘compelling evidence’ of a previously unknown volcanic eruption that occurred 1809 and that may have been responsible for the global cooling noted during the period 1810-19. The evidence comes from ice samples from Greenland and the Antarctic:

‘We’ve never seen any evidence of this eruption in Greenland that corresponds to a simultaneous explosion recorded in Antarctica before in the glacial record’, said Mark Thiemens, Dean of the Division of Physical Sciences at UC San Diego and one of the co-authors of the study. ‘But if you look at the size of the signal we found in the ice cores, it had to be huge. It was bigger than the 1991 eruption of Mount Pinatubo in the Philippines, which killed hundreds of people and affected climate around the world’.

Read on: ‘Previously unknown volcanic eruption helped trigger cold decade’ (UC San Diego news release, 27 October 2009).

[H/T: commenter Perry.]

UPDATE. The 1809 eruption may be unidentified but it’s certainly not ‘unknown’: see comments below.

The Volcanism Blog

Another volcanologist Q&A at Eruptions: Boris Behncke 30 October 2009

Posted by admin in Etna, Italy.
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Following on from the fascinating Chaitén question and answer session he set up at Eruptions with Dr Jonathan Castro, Erik Klemetti has organized a second volcanologist Q&A session, this time with Boris Behncke of the Italian National Institute of Geophysics and Volcanology in Catania.

Boris is a long-established and very good friend of this blog and of Eruptions, and volcano-followers here and elsewhere know him well as someone who is always ready to answer questions and share his expertise both on Etna and Italian volcanoes and on volcanological issues, both scientific and cultural, more widely. So, get your questions together for Boris Behncke and head over to Eruptions!

The Volcanism Blog

Dr Jonathan Castro talks Chaitén at Eruptions 26 October 2009

Posted by admin in Chaitén, Chile, eruptions.
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In a great example of geoblogging outreach, Dr Erik Klemetti of Eruptions recently invited his readers to put questions on the Chaitén eruption to Dr Jonathan Castro. The questions and the answers are now posted at Eruptions, and offer illuminating and fascinating insights into the Chaitén eruption that you won’t find anywhere else. Take a look: Answers to your Chaiten questions from Dr. Jonathan Castro.

For all our Chaitén coverage: Chaitén « The Volcanism Blog.

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
SERNAGEOMIN – Servicio Nacional de Geología y Minería (Spanish)
Erupción del Volcán Chaitén – extensive coverage of the Chaitén eruption

The Volcanism Blog

Vast magma chamber lurking beneath Cascades? 25 October 2009

Posted by admin in volcanoes.
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It’s a racing certainty that before we can say ‘supervolcano obsession’ the Discovery Channel will be all over this:

A vast pool of molten rock in the continental crust that underlies southwestern Washington state could supply magma to three active volcanoes in the Cascade Mountains Mount St. Helens, Mount Rainier and Mount Adams according to a new study that’s causing a stir among scientists. The study, published Sunday in the magazine Nature Geoscience, concluded that the magma pool among the three mountains could be the ‘most widespread magma-bearing area of continental crust discovered so far’.

This theory is controversial, not least because it is based solely on magneto-telluric studies: seismic data on the area gives no support whatever to the suggestion that there is a ‘vast pool of molten rock’ down there. Anyway, Dr Erik Klemetti has everything you need to know about this over at Eruptions: ‘The return of the dreaded “giant magma chamber” of the Cascades’. He’s unconvinced, it’s fair to say.

News
Controversial study suggests vast magma pool under Washington state – 5NEWSonline.com, 25 October 2009

The Volcanism Blog

Volcano-related topics at GSA Portland (2) 20 October 2009

Posted by admin in current research, geoscience, volcanology.
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A couple more presentations on volcanic themes from the current Geological Society of America 2009 Fall Meeting in Portland, Oregon (18-21 October 2009).

Magmatic plumbing of a ‘supervolcano’ exposed to a depth of 25 km (James E. Quick, Southern Methodist University) – the exposure through uplift of a Permian caldera in the Sesia Valley (PDF) reveals the magmatic plumbing system to 25 km depth. (More about this here at The Volcanism Blog, at Eruptions, and at Outside The Interzone here and here.)

Giant impact near India – not Mexico – may have doomed dinosaurs (Sankar Chatterjee, Texas Tech University) – the Shiva basin off the west coast of India may be a meteorite impact crater: as well as killing off the dinosaurs, the crust-vaporizing bang could have enhanced the Deccan Traps eruptions.

UPDATE. I should mention that Callan Bentley of the always-excellent NOVA Geoblog is posting regular reports on the Portland geo-jamboree: GSA update 1, GSA update 2, GSA update 3, GSA update 4. PLUS Jessica at Magma Cum Laude has a list of geobloggers presenting papers, and ongoing updates from the conference. AND Erik at Eruptions has a GSA pre-update.

The Volcanism Blog

Volcano-related topics at GSA Portland (1) 19 October 2009

Posted by admin in current research, geoscience, volcanology.
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The Geological Society of America is currently holding its 2009 Fall Meeting in Portland, Oregon (18-21 October 2009) and with volcanoes featuring prominently in its title, ‘From volcanoes to vineyards – living with dynamic landscapes’, it’s no surprise that there are plenty of volcanic topics in the programme.

Information on particular presentations is regularly updated on the Portland meeting news release page, but as a service to those chiefly interested in things volcanic (and who don’t feel like working their way through the list opening PDF after PDF) I will be summarizing the volcano-related stuff here.

This first post lists contributions from United States Geological Service scientists: the source is this USGS PDF.

Experimental results of carbon sequestration in basaltic rocks (Robert Rosenbauer, USGS) – exploiting the carbon dioxide sequestration potential of basaltic volcanic rocks.

Entrances to tubular caves on Mars? (Glen Cushing, USGS) – imagery from Mars may show entrances to tunnels, possibly volcanic lava tubes.

Can static decompression of magma trigger volcanic eruptions? (Michael Poland, USGS) – the March 2008 explosion at Kilauea may have been triggered by static decompression caused by lava withdrawal from a reservoir beneath the summit caldera: a mechanism that has implications for volcanic hazards worldwide.

A major explosive eruption and aftermath in the Aleutians (Chris Waythomas, USGS) – the geomorphic and ecological impact of the 2008 Kasatochi eruption, particularly in relation to seabirds.

Communicating health hazards of volcanic ash fall (Kristi Wallace, USGS) – a method for significantly improving public hazard communication in relation to volcanic ash fall and air quality hazards.

Virtual volcano tours and geologic concepts (Dina Venezky, USGS) – the use of Google Map technology to provide real-time information about volcanoes around the world.

The Perfect debris flow (Richard Iverson, USGS) – large-scale experiments examining debris-flow dynamics.

Evaluating debris flow hazards by helicopter (Carol Finn, USGS) – dangling experiments over volcanoes from helicopters to evaluate hydrothermal alteration of rocks, which can contribute to destructive debris-flow hazards on volcanic flanks.

The Volcanism Blog

Chaitén magma’s surprising speed 8 October 2009

Posted by admin in Chaitén, Chile, current research, eruptions, geoscience, natural hazards.
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New research just published in Nature indicates that the magma feeding the eruption of Chaitén that began in May 2008 rose from the magma chamber to the surface much faster than anyone thought, and much faster than sticky, viscous rhyolite magma has any right to move. This makes the Chaitén eruption even more interesting than it was already, and suggests that rhyolitic volcanoes may spring nasty surprises on us in the future by building up to eruption very quickly.

Blognote: Dr Erik Klemetti has all you need to know about Chaitén’s racy rhyolite over at Eruptions, and offers the opportunity to put your questions to one of the authors of the Nature study, Dr Jonathan Castro.

For all our Chaitén coverage: Chaitén « The Volcanism Blog.

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
SERNAGEOMIN – Servicio Nacional de Geología y Minería (Spanish)
Erupción del Volcán Chaitén – extensive coverage of the Chaitén eruption

The Volcanism Blog

Tephra not good for the teeth 29 September 2009

Posted by admin in calderas, current research, Germany, Laacher See, natural hazards.
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Are supervolcanoes bad for your teeth? Those of us who grind our teeth whenever slapdash science journalists throw the word ‘supervolcano’ into any story connected with a large-ish volcanic eruption have certainly found this to be so (take a bow, Discovery Channel). However, take out the spurious supervolcano angle and there is a serious scientific story here* about the mechanisms through which volcanic activity directly affects the material basis of human existence.

The Laacher See eruption was a significant volcanic eruption that took place in the Eifel volcanic zone in what is now western Germany around 13,000 years ago. The eruption plume may have reached 20 km altitude and the volume of material ejected was around 6.3 cubic km (source), which on the Volcanic Explosivity Index makes it a VEI=5 or 6. The resulting caldera, filled with water to form a rather lovely lake, is now known as the Laacher See. This eruption, it has been argued, had wide-ranging effects on contemporary human societies, causing large-scale depopulation and migration, disrupting and bringing to an end some cultures and leading to the creation of others.

The eruption covered a vast area with pulverized volcanic debris – the Laacher See Tephra. The tephra reached as far as southern Scandinavia and northern Italy: it has been traced up to 1100 km north, 600 km south, and 100 km southwest of the Laacher See caldera. This very fine and highly abrasive material would have covered everything, making any food consumed by animals and people in affected areas into a form of unpleasant and unhealthy sandpaper. An article in the October 2009 Journal of Archaeological Science (link to abstract at ScienceDirect) by Felix Riede of Aarhus University and Jeffrey M. Wheeler of the University of Cambridge investigates the issue of tephra as a dental abrasive:

Our results show that the Laacher See tephra contained particles roughly twice as hard as even the hardest portions of any of the teeth investigated. We also suggest that fluoride-induced weakening of dental enamel may have further aggravated tooth wear. These mechanisms may have acted in concert to produce elevated levels of, in particular, animal mortality, which in turn may have led to an abandonment of the affected landscapes.

The article suggests that the tephra may have continued to affect the landscape for as much as 300 years after the eruption. Interestingly, recent research based on studies of the current Chaitén eruption suggests that the impact of ashfall from past eruptions has been significantly underestimated, so tephra deposited by eruptions such as Laacher See may have spread wider, and endured for longer, than has been previously thought.

Parts of the Eifel volcanic zone have been active in the very recent past (geologically speaking: less than 10,000 years ago). Current activity at Laacher See itself, says Hans-Ulrich Schmincke’s Volcanism, is marked by ‘a strongly CO2-bubbling area about 200 m long along the east shore … The composition of these gases is magmatic and closely resembles those of Lake Nyos’, and ‘The area around the Laacher See basin is characterized by elevated microseismic activity’ (p. 207). Schmincke regards the Laacher See volcano as dormant, not extinct.

P.S. Dr Klemetti has posted about Laacher See and its abrasive tephra at Eruptions, and has accumulated some very interesting comments on the topic.

* To be fair, the Discovery Channel has quite a decent news report on the Laacher See Tephra research. Just try to ignore the two instances, one being in the title, of that word ‘supervolcano’, and the accompanying picture of a volcano utterly unrelated to the story being reported.

The Volcanism Blog