Predicting volcanic eruptions is notoriously difficult. In large part, that’s because volcanoes are unique, each with its own features and personality: lessons learned from studying one volcano may not directly apply to another. Fortunately, researchers are getting better at finding widely applicable warning signs. Among the best known are increased seismic activity, rising temperatures, widening of magma pools, and the release of gases. New research using satellite imagery now offers a new warning sign for underwater volcanoes: the changing color of the ocean.
The idea is simple: It has long been known that when an underwater volcano prepares to erupt, the gases and compounds it releases affect the composition of the surrounding seawater. Iron-rich water looks yellowish or brown, for example, while aluminum and silicon turn the water white. The challenge has always been to apply this information systematically to make useful predictions. Measuring this color change accurately is not easy.
Yuji Sakuno, assistant professor at Hiroshima University, is working on this issue. As a remote sensing expert, his main tool in this effort is the Japan Space Agency (JAXA) Global Change-Climate Observation Mission (GCOM-C). GCOM-C monitors the oceans every 2-3 days with an accuracy of 250 meters, giving Sacono reliable data on changes in water color over time.
By combining GCOM-C images with eruption information from Himawari-8 (a geostationary satellite), Sakuno was able to observe changes in seawater color about a month before volcanic activity on Nishinoshima Island.
One of the achievements that made this possible was finding a way to accurately measure color, even though sunlight can distort and play with the true color of water. Sakono looked to other areas of research to find a solution: Previous work on hot springs provided the tools needed to counter solar distortion.
Sakuno has big plans for this technology: “In the future,” he said, “I would like to create a system that can predict volcanic eruptions with greater accuracy in collaboration with the Japan Aerospace Exploration Agency (JAXA), and the Maritime Security Agency, which monitors marine volcanoes and related research.”
The study also underscores the value of Earth observation satellites. Most of the spacecraft launched into orbit are not used to study the universe, but instead are diverted to view Earth. Space missions like GCOM-C are designed to improve life at home. Whether it’s enabling communications and GPS, helping us understand and tracking climate change, or keeping us safe from dramatic events like volcanic eruptions, the world’s space infrastructure has very real value to all of us Earthlings.
Learn more:
“To predict an underwater volcanic eruption, a scientist looks at images from space. Hiroshima University
Featured Image Credit: NOAA/National Science Foundation: Superheated molten lava from the underwater West Eye volcano.
