Fault lines mapped from space

Satellite map

Satellite map

It almost seems insensitive to start taking a deep dive into the science behind the events of Monday’s earthquake in Turkey.

More than 22,000 people have already been confirmed dead and an unknown number still lie trapped, with the window to their rescue rapidly closing.

Yet science will go on. The insights gleaned from this event will save lives in the future.

Check out the map on this page. It is the most accurate picture ever produced of how the ground rocked in response to the enormous energies that were unleashed.

The data was acquired in the early hours of Friday by the European Union’s Sentinel-1A satellite as it passed north-south over Turkey at an altitude of 700 km (435 miles).

The Sentinel is equipped with a radar instrument capable of detecting terrain in any weather, day or night.

It regularly scans this earthquake-prone region of the world, plotting the often very subtle changes in elevation on the earth’s surface.

Except, of course, Monday’s changes weren’t all that subtle; they were dramatic. The ground buckled and folded and in some places ripped apart.

Researchers use the technique of interferometry to compare “before” and “after” views. But you don’t need to be an expert to see the consequences for Turkey in Sentinel’s latest map.

The red colors here describe movement towards the satellite since it last flew over the country; blue colors record movement away from the spacecraft.

It is abundantly clear how the terrain has been deformed along and near the East Anatolian fault line.

For both the magnitude 7.8 earthquake that struck first on Monday at 01:17 GMT and the magnitude 7.5 event at 10:24, the movement is “lateral-left”. Namely: whichever side of the fault you are on, the other side has shifted to the left. And several meters in places.

The shocking thing is that the rupture lines have crossed the settlements; in many places they will have passed through buildings.


Artist’s impression: The Sentinel regularly maps earthquake-prone Turkey

Sentinel’s map will help scientists understand exactly what happened on Monday, and this knowledge will feed into their models of how earthquakes work in the region, and eventually into risk assessments that Turkish authorities will use to plan recovery.

There is sure to be a lot of discussion about how the two main tremors were related and what that might mean for further instability.

The map was produced by the UK’s Center for Earthquake, Volcano and Tectonic Observation and Modeling (COMET). Its director, Prof. Tim Wright said Sentinel’s observations clearly drove home the extent of the forces involved.

“News reports always show earthquakes as ‘the epicenter’, as if it were a single point source (like a bomb). In reality, all earthquakes are caused by slipping on extended faults, and the bigger the earthquake , the bigger the fault that ruptured,” he told BBC News.

“We can map those ruptures with satellites because the ground around them is displaced, in this case up to 5m or 6m. The first event’s rupture was about 300km long and the second major event ruptured another 140km or so by a different To put these distances into context, London-Paris is approximately 345km.

“The damage will be highest near the fault, but obviously it also extends over a large region on both sides of the fault. It’s absolutely horrific.”

Collapsed house

The insights will help the Turkish authorities plan the recovery

In the pre-satellite era, geologists mapped earthquake faults by tracing fault lines. It was a laborious process that of course also lost many details. Radar interferometry from space was developed in the 1990s and has become a particularly interesting tool in recent years.

Part of this is due to the quality of the sensors now in orbit, but it’s also the result of more powerful computers and smarter algorithms.

Today, a data product can be obtained on expert computers, ready for analysis, within hours of a satellite making an airpass. Unfortunately, the comet had to wait several days for Sentinel-1A to be in the right part of the sky to get an optimal view of Turkey. But this will improve as more and more radar satellites are launched.

“By the end of the decade, we should be able to do these kinds of analyzes within a day of the most damaging earthquakes, and therefore we would be more useful for relief efforts. As things stand, we are obviously outside the 72-year window. one hour for search and rescue,” said Prof. Wright.

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