SCEINCE

An asteroid destroyed a city 3,600 years ago. It could happen again.


While the inhabitants of an ancient city in the Middle East, now called Tal el-Hamam, took up their daily activities a day about 3,600 years ago, they had no idea that an invisible icy space rock was moving toward them at a speed of about 38,000. miles per hour (61,000 km / h).

Flashing through the atmosphere, the rock exploded into a massive ball of fire about 2.5 miles (4 kilometers) above the ground. The blast was about 1,000 times more powerful than the atomic bomb in Hiroshima. The shocked residents of the city, who stared at him, were instantly blinded. The air temperature rose rapidly above 3,600 degrees Fahrenheit (2,000 degrees Celsius). The clothes and the tree immediately burst into flames. Swords, spears, fenders, and pottery began to melt. Almost immediately the whole city was on fire.

A few seconds later, a huge shock wave invaded the city. Moving at about 740 mph (1200 km / h), it was more powerful than the worst tornado ever recorded. Deadly winds tore through the city, destroying every building. They cut off the top 40 feet (12 m) of the 4-story palace and blew the shuffled debris into the next valley. None of the city’s 8,000 people or animals survived – their bodies were torn and their bones broken into small pieces.

About a minute later, 22 kilometers west of Tal el-Hamam, the winds of the blast hit the biblical city of Jericho. The walls of Jericho collapsed and the city burned to the ground.

It all sounds like the culmination of a Hollywood disaster movie on the edge of your seat. How do we know that all this actually happened near the Dead Sea in Jordan thousands of years ago?

Now called Tall el-Hammam, the city is located about 7 miles northeast of the Dead Sea in present-day Jordan. Source: Journal Nature

Getting answers took nearly 15 years of diligent excavation by hundreds of people. It also included detailed analyzes of excavated material from more than two dozen scientists in 10 states in the United States, as well as in Canada and the Czech Republic. When our group finally publish the evidence recently in Scientific Reports, the 21 co-authors include archaeologists, geologists, geochemists, geomorphologists, mineralogists, paleobotanists, sedimentologists, space impact experts, and physicians.

here it is how we created this picture of devastation in the past.

A storm of fire throughout the city

Years ago, when archaeologists examined the excavations of the ruined city, they saw a dark, about 5 feet (1.5 m) thick layer of mixed coal, ash, molten fenders and molten pottery. It was obvious that a strong firestorm had destroyed this city long ago. This dark band is called the destructive layer.

No one was quite sure what had happened, but this layer was not caused by a volcano, an earthquake or a war. None of them is able to melt metal, fenders and ceramics.

To understand what it can, our group uses Online impact calculator to model scenarios that match the evidence. Created by impact experts, this calculator allows researchers to estimate the many details of a space event based on known impact events and nuclear detonations.

The culprit in Tal el-Hamam seems to be a small asteroid like this felled 80 million trees in Tunguska, Russia in 1908. This would be a much smaller version of a giant, wide-mile rock that pushed the dinosaurs to extinction 65 million years ago.

We had a probable culprit. Now we needed proof of what happened that day in Tal el-Hamam.

Finding “diamonds” in the dirt

Our study revealed an extremely large set of evidence.

An asteroid destroyed a city 3,600 years ago.  It could happen again.
Electron microscope images of numerous small cracks in shocked quartz grains. Source: Journal Nature

There are finely crushed grains of sand called shocked quartz in place, which form at just 725,000 pounds per square inch of pressure (5 gigapascals) – imagine six 68-ton Abrams military tanks arranged on your thumb.

The destructive layer also contains small ones diamonoids which, as the name suggests, are as hard as diamonds. Each of them is smaller than the flu virus. It seems that the wood and plants in the area were instantly turned into this diamond material due to the high pressures and temperatures of the fireball.

An asteroid destroyed a city 3,600 years ago.  It could happen again.
The diamonoids (in the center) in the crater are formed by the high temperatures and the pressure of the fireball on the wood and plants. Source: Journal Nature

Experiments with laboratory kilns have shown that ceramic bubbles and fenders in Tall el-Hammam liquefy at temperatures above 2700 F (1500 C). It’s hot enough to melt the car within minutes.

An asteroid destroyed a city 3,600 years ago.  It could happen again.
Spheres of molten sand (top left), palace plaster (top right) and molten metal (two bottom). Source: Journal Nature

The destructive layer also contains small balls of molten material, smaller than dust particles in the air. Called spheres, they are made of evaporated iron and sand, which melt at about 2900 F (1,590 C).

In addition, the surfaces of ceramics and molten glass are dotted with small molten metal grains, including iridium with melting point 4,435 F. (2,466 C), platinum that melts at 3 215 F (1.768 ° C) and zirconium silicate at 2800 F. (1.540 ° C).

Together, all this evidence shows that temperatures in the city have risen higher than those of volcanoes, war and normal city fires. The only natural process that remains is cosmic impact.

The same evidence is found at certain points of impact, such as Tunguska and Chicxulub Crater, created by the asteroid that caused the extinction of the dinosaur.

One remaining mystery is why the city and over 100 other settlements in the area were abandoned for several centuries after this devastation. It is possible that the high levels of salt deposited during the impact will make it impossible to grow crops. We are still not sure, but we believe that the explosion may have evaporated or spilled toxic levels of Dead Sea salt water into the valley. Without crops, no one could live in the valley for up to 600 years, while minimal rainfall in this desert climate washed the salt from the fields.

Was there an eyewitness to the explosion?

It is possible that an oral description of the destruction of the city was passed down for generations until it was recorded as the story of Biblical Sodom. The Bible describes the devastation of an urban center near the Dead Sea – stones and fire fell from the sky, more than one city was destroyed, thick smoke rose from the fires and the inhabitants of the city were killed.

Could this be an ancient eyewitness account? If so, the destruction of Tal el-Hamam may be the second oldest destruction of a human settlement by cosmic impact, after s. Abu Hurayra in Syria about 12,800 years ago. Importantly, this may be the first written record of such a catastrophic event.

The scary thing is that it will almost certainly not be the last time a human city meets this fate.

An asteroid destroyed a city 3,600 years ago.  It could happen again.
Animation depicting the positions of known near-Earth objects at times in the 20s ending in January 2018. Source: NASA / JPL-Caltech

Tunguska-sized air strikes, such as the one in Tal el-Hamam, could devastate entire cities and regions and pose a serious threat to the modern world. As of September 2021 more than 26,000 known near-Earth asteroids and one hundred short-period near-comets. Man will inevitably collide with the Earth. Millions of others go unnoticed, and some may be heading for Earth now.

Unless orbital or ground-based telescopes detect these deceptive objects, the world may not have a warning, just like the people of Tal el-Hamam.

This article was co-authored with archaeologist research associates Phil Sylvia, geophysicist Alan West, geologist Ted Bunch and space physicist Malcolm Lecompt.The conversation

Christopher R. Moore, Archaeologist and Director of Special Projects in the Savannah River Archaeological Research Program and the Institute of Archeology and Anthropology in South Carolina, University of South Carolina

This article has been republished by The conversation under a Creative Commons license. Read on original article.





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