Archives par mot-clé : Volcanism

Volcanic hazard scenarios: Mount Taranaki, New Zealand

by Geological Society of America, May 3, 2018 in ScienceDaily


Over the last 5000 years, Mount Taranaki volcano, located in the westernmost part of New Zealand’s North Island, produced at least 16 Plinian-scale explosive eruptions, the latest at AD 1655. These eruptions had magnitudes of 4 to 5, eruptive styles, and contrasting basaltic to andesitic chemical compositions comparable to the eruptions of Etna, 122 BC; Vesuvius, AD79; Tarawera, 1886; Pelée, 1902; Colima, 1910; Mount Saint Helens, 1980; Merapi, 2010; and Calbuco, 2015.

Unusual climate during Roman times plunged Eurasia into hunger and disease

by S. Writers,  April 16, 2018 in TerraDaily


A recent study published in an esteemed academic journal indicates that volcanic eruptions in the mid 500s resulted in an unusually gloomy and cold period. A joint research project of the Chronology Laboratory of the Finnish Museum of Natural History and Natural Resources Institute Finland (Luke) suggests that the years 536 and 541-544 CE were very difficult for many people.

Also here in Nature, University of Helsinki

Experimental Constraints on Forecasting the Location of Volcanic Eruptions from Pre-eruptive Surface Deformation

by F. Guldstrand et al., 2018 in Front.Earth.Sci.


Key Points

• We quantitatively analyse pre-eruptive intrusion-induced surface deformation from 33 scaled laboratory experiments resulting in eruptions.

• A robust proxy extracted from surface deformation geometry enables systematic predictions of the locations of a subsurface intrusion and imminent eruption.

• Forecasting an eruption location is possible without geodetic modeling but requires volcano monitoring at high spatiotemporal resolution.

Modern humans flourished through ancient supervolcano eruption 74,000 years ago

by University of Cap Town, March 12, 2018 in ScienceDaily


Early modern humans living in South Africa around 74,000 years ago prospered through the cataclysmic eruption of the Toba supervolcano in Sumatra. The Toba eruption was one of the Earth’s most explosive volcanic events. The environmental effects of this event have been heavily debated, with some researchers having previously proposed that the eruption led to a worldwide volcanic winter that devastated contemporaneous human populations.

An eruption a hundred times smaller than Mount Toba — that of Mount Tambora, also in Indonesia, in 1815 — is thought to have been responsible for a year without summer in 1816. The impact on the human population was dire — crop failures in Eurasia and North America, famine and mass migrations. The effect of Mount Toba, a super-volcano that dwarfs even the massive Yellowstone eruptions of the deeper past, would have had a much larger, and longer-felt, impact on people around the globe (…)

New insight into how magma feeds volcanic eruptions

by University of Liverpool, February 2, 2018  in ScienceDaily


Researchers have provided new insights into how molten rock (magma) moves through the Earth’s crust to feed volcanic eruptions. Using laboratory experiments involving water, jelly and laser imaging, researchers were able to demonstrate how magma magma flows through the Earth’s crust to the surface through magma-filled cracks called dykes.

High geothermal heat flux in close proximity to the Northeast Greenland Ice Stream

by Rysgaard et al., January 22, 2018 in NatureSci.Reports


The Greenland ice sheet (GIS) is losing mass at an increasing rate due to surface melt and flow acceleration in outlet glaciers. Currently, there is a large disagreement between observed and simulated ice flow, which may arise from inaccurate parameterization of basal motion, subglacial hydrology or geothermal heat sources. Recently it was suggested that there may be a hidden heat source beneath GIS caused by a higher than expected geothermal heat flux (GHF) from the Earth’s interior.

Sensitivity to lunar cycles prior to the 2007 eruption of Ruapehu volcano

by T. Girona, C. Huber, C. Caudron,  January 24, 2018 in Nature


A long-standing question in Earth Science is the extent to which seismic and volcanic activity can be regulated by tidal stresses, a repeatable and predictable external excitation induced by the Moon-Sun gravitational force. Fortnightly tides, a ~14-day amplitude modulation of the daily tidal stresses that is associated to lunar cycles, have been suggested to affect volcano dynamics. However, previous studies found contradictory results and remain mostly inconclusive. Here we study how fortnightly tides have affected Ruapehu volcano (New Zealand) from 2004 to 2016 by analysing the rolling correlation between lunar cycles and seismic amplitude recorded close to the crater. (…)

Further proof El Ninos are fueled by deep-sea geological heat flow

by Janes E Kamis, January, 27 in CliateChangeDispatch


The 2014-2017 El Nino “warm blob” was likely created, maintained, and partially recharged on two separate occasions by massive pulses of super-heated and chemically charged seawater from deep-sea geological features in the western North Pacific Ocean. This strongly supports the theory all El Ninos are naturally occurring and geological in origin. Climate change / global warming had nothing to do with generating, rewarming, intensifying, or increasing the frequency of the 2014-2017 El Nino or any previous El Nino.

If proven correct, this would revolutionize climatology and key aspects of many interrelated sciences such as oceanography, marine biology, glaciology, biogeochemistry, and most importantly meteorology. Information supporting a geological origin of El Ninos is diverse, reliable, and can be placed into five general categories as follows: (…)

See also here

Extinction and global warming 250 million years ago

by U. of Bristol, January 10, 2018 in A Watts, WUWT


One of the key effects of the end-Permian mass extinction, 252 million years ago, was rapid heating of tropical waters and atmospheres.

How this affected life on land has been uncertain until now.

In a new study published today, Dr Massimo Bernardi and Professor Mike Benton from the School of Earth Sciences at the University of Bristol show how early reptiles were expelled from the tropics.

Impact of Volcanic Eruptions on Decadal to Centennial Fluctuations of Arctic Sea Ice Extent during the Last Millennium and on Initiation of the Little Ice Age

by J Slawinska and A Robock, November 29, 2017 in AmerMeteorSoc


We evaluate different hypotheses of the origin of the Little Ice Age, focusing on the long-term response of Arctic sea ice and oceanic circulation to solar and volcanic perturbations. We analyze the Last Millennium Ensemble of climate model simulations carried out with the Community Earth System Model at the National Center for Atmospheric Research. We examine the duration and strength of volcanic perturbations, as well as initial and boundary conditions such as the phase of the Atlantic Multidecadal Oscillation, and their impact on decadal to multi-centennial perturbations of the cryospheric, oceanic, and atmospheric components of the climate system.

Do 40,000 volcanoes matter?

by JoNova, December 5, 2017


The scope of our ignorance on the sea floor is really something. There are 1,500 active volcanoes on land, but on the sea floor we are still discovering them all the time. at least 39,000 of them rise one kilometer off the sea floor, but there are suspicions there might be up to 3 million, holey moley. The Hilliers paper estimates that 24,000 submarine volcanoes were not yet discovered in 2007.  Wikimedia is trying to list them. Good luck.

Are underwater volcanoes causing global warming? Oceanic eruptions may have a greater effect on climate than first thought

by Richard Gray, February 6, 2015 in MailOnline


 

  • Geophysicists at Columbia University have found underwater volcanoes erupt in regular cycles that range from a fortnight to 100,000 years
  • They claim that volcanoes on the sea floor are currently experiencing a lull
  • They warn an increase in eruptions will contribute more to climate change 
  • Some climate models have assumed they erupt at a steady rate over time
  • The new research shows they change with the seasons and Earth’s orbit 

 

See also here

Potential links between continental rifting, CO2 degassing and climate change through time

by Sascha Brune et al., March 13, 2017 in NatureGeoscience


Using a numerical carbon cycle model, we find that two prominent periods of enhanced rifting 160 to 100 million years ago and after 55 million years ago coincided with greenhouse climate episodes, during which atmospheric CO2 concentrations were more than three times higher than today. We therefore propose that continental fragmentation and long-term climate change could plausibly be linked via massive CO2 degassing in rift systems.

New map of Antarctic geothermal heat suggests Steig & Mann 2009 weren’t measuring ‘global warming’

by Anthony Watts, November 15, 2017 in WUWT


This is quite interesting. Remember the claim in on the front cover of Nature in 2009 by Steig and Mann that Antarctica was warming, thanks to that “special Mannian PCA math sauce” that was applied to air temperature data to smear surface temperature trends over the entire continent? It was dashed by climate skeptics who wrote a paper. It was accepted for publication and disproved (in my opinion) by a team of credible skeptics that wrote a counter-paper. But, there’s an interesting twist thanks to new and surprising data; Steig and Mann may have captured surface air temperature trends in the exact same areas that have been identified as geothermal hot spots.