Sentinel-1 reveals shifts from the Morocco earthquake

A powerful 6.8-magnitude earthquake struck the Atlas Mountains, about 75 kilometers from Marrakesh, late in the evening of Friday, September 8. This happened in an area located along the fault lines of the European and African tectonic plates, but it was nonetheless a rare event for western Morocco.

Unfortunately, the earthquake claimed thousands of lives, caused buildings and homes to collapse and closed roads. It even caused buildings to shake as far as the country’s northern coast.

On behalf of the International Federation of Red Cross and Red Crescent Societies, the United Nations Institute for Training and Research issued the International Charter “Space and Major Disasters”.

Through the charter, Earth observation assets from different space agencies are integrated so that satellite images of areas hit by extreme events can be provided as quickly as possible to identify and map the extent of the disaster and thus assist teams in their rescue efforts.

Satellites that routinely monitor the Earth from space and provide data to support rapid damage mapping provide a unique tool to aid disaster management.

Since a single space agency or satellite operator alone cannot meet disaster management requirements, ESA and the French space agency CNES launched the International Charter for Space and Major Disasters in 1999.

The Copernicus Emergency Mapping Service was also activated to assist in the exchange of satellite data in response to the Moroccan earthquake, in line with the existing practical cooperation with the International Charter.

So far, high-resolution images from the French Pléiades satellite have been used to create detailed maps of damage in the affected areas. Pléiades is also part of the European Space Agency’s third-party mission programme.

The first damage mapping products were released on September 11, and more have followed.

Rescuers can use these maps, like the one shown above, to determine the best course of action, by identifying which routes to take and which bridges to avoid in the event of a collapse, for example.

“It is clear that time is of the essence when disasters strike,” said Philippe Paley, ESA Representative for the International Compact. Through the Charter and the Copernicus Emergency Mapping Service, helping ensure the right satellite data is delivered to aid relief efforts is part of our mission.

As the response to the Morocco disaster continues, scientists are using measurements from the Copernicus Sentinel-1 mission in a technique known as “interferometry” to compare before and after views of the region.

The Copernicus Sentinel-1 mission carries a radar instrument that can sense the Earth and “see” through clouds, both day and night.

Among the mission’s many uses, it routinely tracks subtle changes in Earth’s surface elevation. When an earthquake occurs, changes in the surface are obviously more noticeable than gradual subsidence or uplift.

These radar images allow scientists to observe and analyze the subtle effects that earthquakes have on the Earth’s surface.

In the case of the Morocco earthquake, Sentinel-1 data were combined to measure the surface displacement that occurred between the acquisition on August 30 and the one after the earthquake on September 11.

This has led to an interferogram that shows a colorful ‘fringe’ pattern and allows scientists to understand more about the nature of the earthquake and the risk of more hazards in the future.

“Immediately after Sentinel-1 obtained data about the earthquake zone, Earth observation processing chains available in the user community allowed retrieval of information about terrain deformation,” Dr. Bali explained.

“This is the case with the interferogram generated in an automated and rapid way by the UK-based COMET LiCSAR, and with the Geohazard Exploitation Platform using the DIAPASON InSAR service of the French space agency CNES.

“Accurate deformation maps are created for scientific purposes related to geological hazards and can be used to advise disaster response teams regarding the hazard event.”

“The Charter and the Copernicus Emergency Mapping Service are extremely valuable tools to support vital disaster relief efforts,” noted Simonetta Celli, ESA’s Director of Earth Observation Programs.

“Earth-orbiting satellites are unique in their ability to provide not only wide views of affected areas but also highly detailed information as seen here provided by the Pléiades mission.

“Because the Copernicus Sentinel-1 mission carries radar, it can see through clouds, so it is also often used to map dangerous floods. In the case of the Morocco earthquake, the value of the mission was to measure how the surface changed, which will be important once the immediate crisis is over and the Restoration process.