New data shows that a section of Grindavík, Iceland, sunk up to 1 meter, or more than 3 feet, in only a matter of hours as earthquakes rattled the region in advance of a possible volcanic eruption.
The ground deformation, which some Iceland media organizations are calling a "sinkhole," is a sign that an eruption at the Fagradalsfjall volcano could occur soon. The impending eruption has led to fears, and officials ordered an evacuation of Grindavík days ago.
A new map based on interferometric synthetic aperture radar shows the extent of the ground deformation in Grindavík. InSAR data maps out this deformation by using radar images collected by satellites, according to the U.S. Geological Survey (USGS).
"Newly released InSAR data shows that some parts of Grindavík, Iceland have sunk by up to one meter in a matter of hours. Astonishing ground deformation," social media user Nahel Belgherze posted on X (formerly Twitter) on Monday along with an image of the data.
Newly released InSAR data shows
— Nahel Belgherze (@WxNB_) November 13, 2023
that some parts of Grindavík, Iceland have sunk by up to one meter in a matter of hours.
Astonishing ground deformation. pic.twitter.com/ZZKbb1hahi
The image is of a map with colored markings showing the extent of the ground deformation. A patch of purple coloring shows the area of Grindavík where the deformation reaches 1 meter.
As magma accumulates underground, the ground surface swells. When magma leaves the reservoir, possibly in advance of an eruption, the ground sinks, according to the USGS.
The ground deformation discovery comes after thousands of earthquakes have hit Iceland over the past few days. A magma tunnel extending across Grindavík also was discovered, heightening fears that an eruption was imminent.
Iceland has since declared a state of emergency because of the threat, and police have ordered residents to evacuate Grindavík, a coastal town of nearly 4,000 people. Some residents were permitted back into the town briefly over the weekend to gather pets and belongings. If the volcano remains active, residents may not be able to return to their homes for weeks.
Earthquakes often occur in the days leading up to a volcanic eruption because magma is moving and applies increased pressure to the surrounding rocks.
The Icelandic Met Office has released daily reports on the volcano's status. The most recent update, on Tuesday, said the office is conducting "continuous monitoring of seismicity and ground deformation in the Grindavík – Svartsengi region."
"In summary, the likelihood of an eruption remains high. If an eruption occurs, the most likely location will be on the magma intrusion," the report said. "Our latest hazard assessment does not indicate any other potential eruption sites."
Newsweek reached out to the Icelandic Met Office by email for comment.
Fagradalsfjall last erupted in July. The volcano was dormant for over 800 years until it erupted in 2021. Eruptions have occurred roughly every year since the 2021 eruption.
Iceland is one of the most volcanically volatile areas in the world, with about 30 active sites.
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