Chile earthquake seen by satellite

Chile earthquake seen by satellite

September 25, 2015
Head of Communication

Just a day after the earthquake in Chile on September 16, geologists worldwide studied satellite images of the quake prepared in Tromsø. How is this possible?

The earthquake that rocked the coast of Chile on September 16 had a magnitude of 8.3 on the Richter scale. The death toll from the earthquake and subsequent tsunami now stands at 13, while more than 9,000 people have been left homeless.

Just a day after the earthquake, Norut Senior Research Scientist Yngvar Larsen was able to send the first satellite images showing the extent of the quake. Larsen heads an international research group linked to the European Space Agency (ESA) Copernicus programme. The Copernicus satellite Sentinel-1 passed over Chile just 10 hours after the quake.

Two metre movement

The scientists have developed a new technique called radar interferometry (InSAR), which involves placing two radar images on top of each other. The images, which are called interferograms, show changes on the earth surface. Each colour cycle on the image, known as a fringe, corresponds to a movement of approximately 2.8 cm. The interferogram from Chile is based on combining radar images taken on August 24 and September 17.

“The images show us that there have been movements in a north-south as well as east-west direction. Most of the movement is expected to have been in a horizontal direction, so at its peak there can have been movement of up to two metres in an east-west direction,” says Yngvar Larsen.

“In the flight direction of the satellite, roughly north-south, there is horizontal movement of around 50 cm. We can also measure displacement of around 1.4 meters along the viewing direction of the radar, which is a mixture of vertical and east-west. We cannot distinguish between vertical and east-west movement until the satellite passes again with other geometry,” says Larsen.

Enormous interest

Since the images were supplied so soon after the earthquake, they have naturally generated considerable interest among geologists and the remote sensing environment worldwide.

This article on the science blog Earth&Space gained in excess of 125,000 hits just one and a half days after publication on Friday:

This is how much the ground moved during Chile’s massive earthquake

Read more about the satellite images from the earthquak in Chile

Chile earthquake on the radar (ESA)

Chile earthquake: Sentinel-1 insar analyses (Insarap-prosjektet)