Bathers enjoying the Dead Sea.
Bathers enjoying the Dead Sea. Photo by Gil Cohen-Magen
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A team of scientists has developed a method of more precisely predicting the development sinkholes by the Dead Sea, which should make the area safer for visitors and people working there.

Researchers say use of an Italian earth-observation satellite system known as Cosmo-Skymed has significantly improved their ability to predict when and where sinkholes will form. The technology should give them a few month's notice before a sinkhole actually appears.

Currently, geologists can only map out the general area where sinkholes might form.

These destructive pits are caused by the continuing decline in the level of the Dead Sea.

Sinkholes are created as the Dead Sea's water recedes, allowing fresh water to flow into the underground layer of salt once covered by the Dead Sea. The fresh water dissolves the salt, creating large underground cavities, into which the surface collapses.

According to Geological Survey of Israel, several hundred sinkholes appear every year, some as large as 12 meters in diameter and 20 meters deep. They have ruined some of Kibbutz Ein Gedi's tourism facilities and threaten Route 90, the main road along the Dead Sea. In addition, they can be dangerous, if someone falls into one (which has happened at the Dead Sea ).

Researchers have been trying to improve the ability to predict when sinkholes will appear, in order to reduce the danger they can pose. The research team includes Dr. Gideon Baer of the Geological Survey of Israel; doctoral student Ran Nof; Prof. Yehuda Eyal of Ben-Gurion University; and Dr. Alon Ziv of Tel Aviv University. They were assisted by Dr. Eli Raz of Kibbutz Ein Gedi in the Dead Sea area, who is conducting an ongoing survey of the development of the sinkholes.

"The radar waves broadcast by the satellite allow us to decode changes in the earth's surface within millimeters. In this way we can analyze processes occuring on the surface before a sinkhole appears," Baer explained. Baer said these methods have been used in the past to detect changes in the surface of areas where earthquakes occur or volcanoes erupt.

Scientists once thought that sinkholes occured immediately after the dissolution of the salt layer resulted in a space that reached the surface. However, observing a sinkhole that was developing along a pipeline near the Dead Sea Works led them to realize that, in fact, the land sinks gradually into the space that develops below. "Our observation of this site showed us that the ground had begun to sink three months before the sinkhole appeared."

"The Italian satellite data, which is received every 16 days, allows us to measure changes in the rate of the sinking of the surface, and estimate when the sinkhole will appear," Baer said, adding that the team also used aircraft to take laser measurements of the site.

When the team sees the ground start to sink in a particular way, they know there is a chance that a sinkhole is about to open up. If the ground stops sinking, they know the space below is small and the ground will not actually collapse above it.

Baer noted that the research is still in its early stages and scientists have only mapped a small part of the areas using the new information.

Since October 2011, the Dead Sea has receded a total of 1.23 meters, which means sinkholes could begin appearing more rapidly.