Volcano flag

from Wikipedia, the free encyclopedia
QA geosciences

This article was due to content flaws on the quality assurance side of Geosciences portal entered. This is done to increase the quality of the articles in the geosciences topic. Please help to correct the deficiencies or take part in the discussion .  ( + )
Reason: The definition of the lemma is empty and probably at least incomplete. In the discussion , doubts arose as to whether the term is capable of lemma at all. In the article serving as a source, it appears on the sidelines. The content of the article fits under volcanic gas . Another reading is that a forwarding to the eruption column would be sufficient, which is not certain due to the lack of expert knowledge involved. - Sitacuisses ( discussion ) 23:13, 26 Dec. 2012 (CET)

Not just ash: Condensing water vapor, which previously escaped from the crater in gaseous form, shows how the wind blows the hot rising gases into the typical volcanic plume. Here the Soufrière Hills volcano on Montserrat .
Condensing water vapor shows the volcanic plume of Mount Erebus , Ross Island , Antarctica
Eruption column of Mount Redoubt on April 21, 1990, Alaska
Volcanic flag of the Halemaʻumaʻu crater in the caldera of the Kīlauea volcano in the Hawaii Volcanoes National Park

In current volcanology, the emissions that a volcano emits into the atmosphere are referred to as volcanic plumes. These sometimes consist of solid particles ( volcanic ash ) and always also of volcanic gas . While the term colloquially often only means the visible cloud that emanates from a volcano, volcanologists also use it to refer to the gas emissions that are invisible to the eye, can only be seen and measured with their instruments. Sometimes given off continuously outside of outbreaks and visible activities.

During a volcanic eruption , usually at a time of very strong emissions, when lava and lava fragments are exposed to high pressure e.g. Sometimes they are thrown hundreds of meters high into the atmosphere, the volcanic plume is called an eruption column .

In the literature, the phenomenon of volcanic emissions into the atmosphere is also referred to by the terms smoke plume or volcanic emissions .

Today, volcanic ash emissions are preferably measured with Lidar (Light Detection And Ranging), a remote sensing instrument that uses laser beams to measure the concentration of dust particles in the ash cloud. This method became known to the general public when, in 2010, the German Aerospace Center (DLR) measured the volcanic plume of the Eyjafjallajökull volcano with the help of a lidar mounted on a Falcon 20E , which was a DLR research aircraft to determine whether the airspace was safe for aircraft again.

The gas emissions from volcanoes have been studied for about 150 years. It has been shown that almost all volcanoes give off water vapor (H 2 O), carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ) and hydrogen chloride (HCl). The measurements of the gas emissions are nowadays preferably carried out using the technique of differential optical absorption spectroscopy . According to current knowledge, it is assumed that halogens are much more soluble than sulfur in hot magma , while sulfur is much more soluble than carbon dioxide. When the magma rises, the carbon dioxide is first outgassed, then gaseous sulfur and finally halogens such as chlorine , bromine and fluorine . Bromine monoxide was first detected in a volcanic plume in 2002, namely that of the Soufrière Hills volcano on the Caribbean island of Montserrat .

Effects and dimensions

With their gas emissions, volcanoes exert a great influence on life on earth over long and in individual cases also over short periods of time.

  • Viewed over geological time periods, volcanic CO 2 emissions represent a potential climate feedback mechanism that has likely saved the earth from permanent global icing.
  • Over a period of years, however, the emission of trace substances and ash can lead to greatly reduced solar radiation and thus cooling on the ground. In 1991, in the years following the eruption of the Philippine volcano Pinatubo, a decrease in atmospheric temperatures of around 0.5 degrees was measured.
  • A particularly impressive example of the devastating effect of volcanic eruptions on the climate is the so-called year without a summer (1816), in which North America and Europe suffered catastrophic crop failures and famines. Ash layers from large volcanic eruptions that were associated with reduced temperatures can also be detected in ice cores.

An example of the dimension of gas emissions in volcanic plumes is the Popocatépetl volcano , which is about 60 km away from the 20 million population agglomeration of Mexico City . During periods of increased activity between March 1996 and January 1998, the Popocatépetl had repeated eruptions in which at times over 10,000 tons of sulfur dioxide per day were released into the atmosphere. This corresponded to around a quarter of the total anthropogenic - man-made - sulfur emissions in Europe and around half of the emissions in Central and South America combined.

Volcanoes emit large amounts of halogens such as bromine or chlorine, which have a significant impact on the ozone balance .

Determination of the quantity of the escaping gases

The scientists determine the emission rate of a gas from a volcano by first measuring the total amount of the substance in a cross section of the plume perpendicular to the direction of propagation using the DOAS method and then multiplying this by the wind speed . The emission rate gives z. B. on how much SO 2 is emitted per second, day or year.

The wind speed was previously determined by measuring the wind on the ground or at the crater rim. However, these proved to be complex, imprecise and sometimes even dangerous. The data obtained were also only partially representative of the wind direction and speed actually prevailing in the volcanic plume. Today, the DOAS method is used for the so-called correlation method, whereby the DOAS device is quickly directed to two averted viewing directions. The process takes advantage of the fact that the volcanic plume is not mixed homogeneously and the gases are rather unevenly distributed. This results in a structured time series for each of the viewing directions. Every time a cloud with an increased sulfur dioxide concentration passes, only one measuring point reports a maximum, a short time later the other measuring point. The time offset corresponds to the time it takes for the volcanic plume to move from one direction of view to the other. Due to the knowledge of the angle between the viewing directions and the distance to the volcanic plume, one also knows the distance between the two viewing directions in the plume. The wind speed is calculated from the quotient of distance and time offset.

Development of research

In recent times, the instruments for monitoring volcanic emissions have been significantly improved. In 2001, researchers from the Working Group on Atmosphere and Remote Sensing at the Institute for Environmental Physics at Heidelberg University, together with scientists from Chalmers University of Technology, Gothenburg , Sweden, carried out DOAS measurements in volcanic plumes for the first time. Although spectroscopic measurements of sulfur dioxide in volcanic plumes had been carried out using other methods since the 1970s, the new method allowed the construction of much smaller and therefore more manageable instruments. In addition to sulfur dioxide, the researchers were also able to detect a large number of other trace gases such as halogen and nitrogen oxides for the first time.

The different solution behavior of the various gases in the magma has led to the question of whether changes in gas emissions could provide information about the behavior of the magma, e.g. B. Show ascending processes and thus also announce outbreaks. For this purpose, research was and is taking place using systematic measurements, e.g. B. on Popocatepetl ( Mexico ), Masaya ( Nicaragua ), Etna ( Italy ), Gorely , Mutnovsky (both Kamchatka ) and Nyiragongo ( Congo ). Continuous measuring stations have been set up at Popocatepetl, Masaya and Etna.

The possibilities of measuring volcanic emissions with the help of satellites have also been greatly improved. Since the start of the Global Ozone Monitoring Experiment (GOME) in 1995, the detection limits have been significantly reduced thanks to improved spectral scanning. Other instruments with similar properties ( SCIAMACHY , OMI , GOME-2) were added later. Thanks to this greatly improved detection limits and comprehensive spatial coverage, modern satellite instruments open up considerably expanded access to global monitoring of volcanic activity and quantification of its emissions. For example, the atmospheric transport of volcanic emissions can often be tracked over several days using satellite observations (in individual cases over periods of up to a month). This made it possible to study the effects of volcanoes on a regional to global scale. In addition, volcanoes in remote regions could be measured for the first time by satellite observation.

Alien volcanic flags: Jupiter's moon Io

Two volcanic flags on Jupiter's moon Io

Three volcanic flags were discovered on Jupiter's moon Io , two small ones that emanate from the Prometheus and Amirani volcanoes , and the Tvashtar volcanic flag, which reaches up to 290 kilometers. See also volcanism on Jupiter's moon Io .

literature

  • AJ Krueger: Sighting of El Chichon sulfur dioxide clouds with the Nimbus 7 Total Ozone Mapping Spectrometer . Science 220: 1277-1379 (1983).
  • C. Seftor, N. Hsu, J. Herman, P. Bhartia, O. Torres, W. Rose, D. Schneider, N. Krotkov: Detection of volcanic ash clouds from Nimbus 7 / total ozone mapping spectrometer. Journal of Geophysical Research 102 (D14), 16749-16759 (1997).
  • N. Bobrowski, G. Hönninger, B. Galle, U. Platt: Detection of bromine monoxide in a volcanic plume . Nature 423, 273-276, doi: 10.1038 / nature01625 (2003).
  • S. Guo, GJS Bluth, WI Rose, IM Watson, AJ Prata: Re-evaluation of SO2 release of the June 15, 1991 Pinatubo eruption using ultraviolet and infrared satellite sensors . Geochemistry, Geophysics, Geosystems 5, Q04001, doi: 10.1029 / 2003GC000654 (2004).
  • MF Khokhar, C. Frankenberg, M. Van Roozendael, S. Beirle, S. Kuhl, A. Richter, U. Platt, T. Wagner: Satellite observations of atmospheric SO2 from volcanic eruptions during the time-period of 1996-2002 . Advances in Space Research 36 (5), Atmospheric Remote Sensing: Earth's Surface, Troposphere, Stratosphere and Mesosphere - I, pp. 879-887, doi: 10.1016 / j.asr.2005.04.114 (2005).
  • N. Theys, M. Van Roozendael, B. Dils, F. Hendrick, N. Hao, M. De Mazière: First satellite detection of volcanic bromine monoxide emission after the Kasatochi eruption . Geophysical Research Letters 36, L03809, doi: 10.1029 / 2008GL036552 (2009).
  • S. Guo, GJS Bluth, WI Rose, IM Watson, AJ Prata: N. Theys, M. Van Roozendael, B. Dils, F. Hendrick, N. Hao, M. De Mazière: First satellite detection of volcanic bromine monoxide emission after the Kasatochi eruption. Geophysical Research Letters 36, L03809, doi: 10.1029 / 2008GL036552 (2009).
  • BW Levin, AV Rybin, NF Vasilenko, AS Prytkov, MV Chibisova, MG Kogan, GM Steblov, DI Frolov: Monitoring of the eruption of the Sarychev Peak Volcano in Matua Island in 2009 (central Kurile islands) . Doklady Earth Sciences 435 (1), 1507-1510 (2010).
  • Christoph Kern: Spectroscopic measurements of volcanic gas emissions in the ultra-violet wavelength region (spectroscopic measurements of volcanic gas emissions in the ultra-violet wavelength range). Dissertation, 2009.
  • Christoph Kern, Ulrich Platt: Telegram from the depths , Ruperto Carola, issue 1/2010
  • Leif Vogel: Volcanic plumes: Evaluation of spectroscopic measurements, early detection, and bromine chemistry (German translation of the title: Vulkanfahnen: Evaluation spectroscopic measurements, early detection and bromine chemistry) , dissertation 2011, permanent URL on the Heidelberg document server : ub.uni-heidelberg .de .
  • Thomas Wagner, Christoph Hörmann, Marloes Penning de Vries, Holger Sihler: Global monitoring of volcanic emissions with satellite instruments. Research Report 2011 - Max Planck Institute for Chemistry .
  • Nicole Bobrowski: Gas emissions, read like hieroglyphics. In: forschung - Das Magazin der Deutschen Forschungsgemeinschaft, 2/2012, pp. 4–9 ( online: PDF; 3.34 MB ).

See also

Web links

Individual evidence

  1. ↑ The volcano is calling - DLR measurement flights over Iceland.
  2. ^ Nicole Bobrowski: Gas emissions, read like hieroglyphs. In: forschung - The magazine of the German Research Foundation, 2/2012, p. 6.
  3. ^ A b Nicole Bobrowski: Gas emissions, read like hieroglyphs. In: forschung - The magazine of the German Research Foundation, 2/2012, p. 7.
  4. ^ Nicole Bobrowski: Gas emissions, read like hieroglyphs. In: research - The magazine of the German Research Foundation, 2/2012, p. 8.
  5. ↑ a b Thomas Wagner, Christoph Hörmann, Marloes Penning de Vries, Holger Sihler: Global Monitoring of Volcanic Emissions with Satellite Instruments , Research Report 2011 - Max Planck Institute for Chemistry
  6. ↑ Christoph Kern, Ulrich Platt: Feuerberg over the megacity. The thing about the volcanic and man-made sulfur dioxide. In: Scinexx as of October 1, 2010; Retrieved December 30, 2012.
  7. ↑ Christiane Voigt (Institute for Atmospheric Physics): Research flights: DLR examines the influence of contrails and volcanic emissions on the climate , press release from the German Aerospace Center (DLR) from October 7, 2011
  8. ↑ a b Christoph Kern, Ulrich Platt: In a safe distance ... Volcanic gas measurement far away from the dangerous crater In: Scinexx , as of October 1, 2010.
  9. ↑ Christoph Kern, Ulrich Platt: Waiting for an emergency. What if the Popocatépetl breaks out? , in Scinexx, as of October 1, 2010; Retrieved December 30, 2012
  10. ^ Nicole Bobrowski: Gas emissions, read like hieroglyphs. P. 9.
  11. ↑ Io the galilean moon section: Io the volcanic moon