Mauna Loa Awakens – Satellite view of the world’s largest active volcano
During Mauna Loa’s first eruption in nearly four decades, satellites detected the volcano’s nighttime glow and a flurry of sulfur dioxide.
Hawaii Mauna Loa– the world’s largest active volcano – has been quiet for the past four decades. But in November 2022, the volcano began to stir.
In early October 2022, the first signs of unrest appeared when US Geological Survey (USGS) data showed a tenfold increase in small earthquakes beneath the volcano’s summit caldera. This was the result of the underground movement of magma. Earthquake swarms continued sporadically until November 27, 2022, when new fissures began spewing lava onto the caldera floor at 11:30 p.m. local time. Most of the lava fountains were only a few yards high, although some of the tallest rose as high as 30 to 60 meters. Although other fissures had opened slightly to the northeast the next day, the caldera’s lava flows had subsided by then.
The bright glow of the eruption was visible[{” attribute=””>NASA and NOAA satellites orbiting hundreds of miles above the surface. The image above was acquired at 2:25 a.m. local time (12:25 UTC) on November 28 by the “day-night band” of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-NASA Suomi NPP satellite. For comparison, the image above shows the same area on October 29, 2022, before the eruption had begun.
Some clouds on November 28 scattered light from the eruption and urban areas, making it more diffuse. “It also appears that the lava emitted by the eruption was so bright that it saturated the probe, producing a ‘post-saturation recovery plume’ along the VIIRS scan to the southeast,” noted Simon Carn, a volcanologist at Michigan Tech. “These lines are only visible in very strong sources of visible radiation.”
Among the substances leaking from the volcano was sulfur dioxide (SO2), a pungent gas that reacts with oxygen and water to form a gray volcanic haze called vog. The map above shows where the European Space Agency’s Sentinel-5P satellite detected sulfur dioxide in the mid-troposphere with its Tropospheric Monitoring Instrument (TROPOMI) sensor. The Ozone monitoring device (OMI) – the predecessor of TROPOMI – on NASA’s Aura satellite makes similar measurements. The Finnish Nuclear Power Plant’s, NOAA-20 and NOAA-21’s Ozone Mapping and Profiling Suite (OMPS) also works.
Vog (volcanic smog) is a visible haze consisting of gas and aerosol of small particles and acidic droplets produced by sulfur dioxide (SO2) and other gases released from the volcano chemically interact with sunlight and atmospheric oxygen, moisture and dust. Volcanic gas emissions can harm the environment and the health of local residents. Vog is a hazard particularly associated with Hawaii’s volcanoes.
“The eruption is overflowing rather than explosive, although its initial phase on the night of Nov. 28 was quite energetic, spewing sulfur dioxide to high altitudes, possibly as far as the tropopause,” Carn said. “That’s unusual for this type of eruption.”
NASA scientists used both OMPS and TROPOMI measurements to measure emissions of about 0.2 teragrams of sulfur dioxide on November 28. “Both sensors measured within 5 minutes of each other in the early afternoon and are excellent, despite having different algorithms,” said researcher Nickolay Krotkov. atmospheric scientist at NASA’s Goddard Space Flight Center. For comparison: Mauna Loa’s previous eruption in March-April 1984 released approx. 1.2 teragrams of sulfur dioxide during the three-week eruption.
“Eruptions at Mauna Loa typically last a few weeks, but this is a developing eruption, and we’re just in the early days,” added Ashley Davies, a volcanologist at NASA’s Jet Propulsion Laboratory. “The US Geological Survey’s Hawaiian Volcano Observatory closely monitors and assesses all aspects of the eruption and is a great source of information for people wondering about the risks and dangers of this eruption.
Scientists who join NASA disaster program are actively monitoring the eruption and are currently providing information and images to other agencies – including the Hawaiian Volcano Observatory and FEMA – that are responding to the eruption.
NASA Earth Observatory images taken by Joshua Stevens using VIIRS day-night band data from the Suomi National Polar-orbiting Partnership and modified Copernicus Sentinel 5P data (2022) processed by the European Space Agency.