Data from the EU’s Sentinel 1-A satellite has revealed both upward and downward rock movements in the region where North Korea has been conducting its nuclear tests.
Using images taken from a European radar satellite, researchers have learned more about how the ground shifted following North Korea’s mysterious nuclear test in January. According to reports from North Korea’s media, the secretive state conducted an underground detonation of a hydrogen bomb on January 6, 2016 (although it has not been independently verified if the explosion was indeed the result of a hydrogen bomb). The data collected by the satellite could prove invaluable in finally verifying the claims.
Using the data to crack North Korea’s test
The EU spacecraft uses a technique called interferometry to sense surface movements and can find the difference between ‘before’ and ‘after’ radar images of the Earth’s surface. This allows for even very subtle changes in ground composition to be detected. Its data shows rock above the blast zone going down by up to 7cm in one area and rising 2-3cm in another. The imagery was released by Germany’s Institute for Geosciences and Natural Resources (BGR) which advises the German federal government on matters related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT).
“This is a very important result because in the past the location of nuclear tests was based only on seismological data, and now we have an indication from other technologies,” Dr. Nicolai Gestermann, a geophysicist at BGR told the BBC. He presented the research at the European Geosciences Union General Assembly, held this week in Vienna, Austria.
All of North Korea’s tests (2006, 2009, 2013 and 2016) appear to have occurred at a site called Punggye-ri, also known as P’unggye-yok, in a remote region in the east of the country, near the town of Kilju.
The bomb test in January, which seismologists say had a magnitude of 5.1, also may not be a thermonuclear blast, as North Korea claimed. The researchers suggest that it shares many characteristics with the 2013 test, which scientists have said could also be a conventional bomb blast designed to mimic a nuclear test. The estimated yield of the January test was 10 kilotons of TNT-equivalent, Dr. Gestermann said.
Previously, a team of researchers used similar analysis to examine more about how a series of underground nuclear tests conducted by the US government impacted the surface of a test site in Nevada.
Sentinel-1A got its first view of the test site following the explosion on 13 January, and this was compared with an observation acquired on 1 January. However, due to the gap in time between the blast and the subsequent image retrieval, scientists cannot say whether the ground deformation occurred at the same time as the detonation or a few days later.
Launch of Sentinel 1-B
On April 25, 2016, the European Space Agency launched Sentinel 1-B, Sentinel 1-A’s sister satellite, into orbit to deliver information for numerous services, from monitoring ice in polar seas, to tracking land subsidence and for responding to natural and manmade disasters.
“The launch of Sentinel-1B marks another important milestone,” said ESA’s Director General Jan Woerner. “Orbiting 180° apart, the two satellites optimize coverage and data delivery for services that are making a step change in the way our environment is managed.”
Moreover, the data collected from Sentinel 1-A on the North Korean nuclear test also highlights the important role that the two EU satellites could play in ensuring continued peace and security in an ever-troubled global political environment.
Cordis: Based on media reports