• To predict underwater volcano eruptions,

    From ScienceDaily@1:317/3 to All on Thu Jul 8 21:30:34 2021
    To predict underwater volcano eruptions, scientist looks at images from
    space

    Date:
    July 8, 2021
    Source:
    Hiroshima University
    Summary:
    A new study monitored satellite images to obtain sea discoloration
    data as a novel indicator in detecting if an underwater volcano's
    eruption is imminent.



    FULL STORY ==========================================================================
    A new study suggests sea discoloration data obtained from satellite
    images as a novel criterion in predicting if eruption looms for an
    underwater volcano.


    ========================================================================== There have been frequent eruptions of submarine volcanoes in recent
    years. The past two years alone recorded the explosions of Anak Krakatau
    in Indonesia, White Island in New Zealand, and Nishinoshima Island
    in Japan. Observing signs of volcanic unrest is crucial in providing life-saving information and ensuring that air and maritime travel are
    safe in the area.

    Although predicting when a volcano will erupt can be difficult as each
    behaves differently, scientists are on the lookout for these telltale
    signs: heightened seismic activity, expansion of magma pools, increases
    in volcanic gas release, and temperature rises.

    For submarine volcanoes, Yuji Sakuno, remote sensing specialist and
    associate professor at Hiroshima University's Graduate School of Advanced Science and Engineering, proposed a new indicator -- sea color.

    The relationship between the chemical composition of discolored seawater
    and volcanic activity has been known for a long time. Still, there
    have been very few quantitative studies that used remote sensing to
    explore it. And among these few studies, only the reflectance pattern
    of discolored seawater has been analyzed.

    "This is an extremely challenging research result for predicting volcanic disasters that have frequently occurred in various parts of the world
    in recent years using a new index called sea color," Sakuno said.



    ==========================================================================
    "I was the first in the world to propose the relationship between the sea
    color information obtained from satellites and the chemical composition
    around submarine volcanoes." The findings of the study are published
    in the April 2021 issue of the journal Water.

    Sakuno explained that volcanoes release chemicals depending on their
    activity, and these can change the color of the surrounding water. A
    higher proportion of iron can cause a yellow or brown discoloration, while increased aluminum or silicon can stain the water with white splotches.

    One problem, however, is that sunlight can also play tricks on sea
    color. The study looked at how past research that chromatically analyzed
    hot spring water overcame this hurdle and fixed brightness issues. A
    relational model between seawater color and chemical composition was
    developed using the XYZ colorimetric system.

    Sakuno examined images of Nishinoshima Island captured last year by
    Japan's GCOM-C SGLI and Himawari-8 satellites. Himawari-8 was used to
    observe volcanic activity and GCOM-C SGLI to get sea color data. GCOM-C
    SGLI's short observation cycle -- it takes pictures of the ocean every
    2-3 days -- and high spatial resolution of 250 m makes it an ideal choice
    for monitoring.

    Using the new indicator, Sakuno checked satellite data from January to
    December 2020 and was able to pick up signs of looming volcanic unrest
    in Nishinoshima Island approximately a month before it even started.

    "In the future, I would like to establish a system that can predict
    volcanic eruptions with higher accuracy in cooperation with the Japan
    Aerospace Exploration Agency (JAXA), the Maritime Security Agency,
    which is monitoring submarine volcanoes, and related research," he said.

    ========================================================================== Story Source: Materials provided by Hiroshima_University. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Yuji Sakuno. Trial of Chemical Composition Estimation Related to
    Submarine Volcano Activity Using Discolored Seawater Color Data
    Obtained from GCOM-C SGLI. A Case Study of Nishinoshima Island,
    Japan, in 2020.

    Water, 2021; 13 (8): 1100 DOI: 10.3390/w13081100 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/07/210708103617.htm

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