Earthquakes come and go, often leaving destruction behind. What they luckily don’t usually do is turn around immediately and come back for another push. Except … it looks like they can do it on very rare occasions.

In a new study, scientists have uncovered evidence of an unusual and almost unprecedented boomerang earthquake that shook the deep seafloor under the Atlantic Ocean in 2016.

This earthquake, dubbed “reverse super-shear rupture”, occurred along the Romansh fracture. It is an area that lies near the equator, about halfway between the east coast of Brazil and the west coast of Africa.

The rift, which stretches about 900 kilometers between the South American and African tectonic plates, adjacent to the Mid-Atlantic Ridge, caused a 7.1 magnitude earthquake in August 2016, which was detected by underwater seismometers in the region, as well as by remote monitoring stations.

Analysis of the signals reveals that this was not an ordinary earthquake, but a strange earthquake that went one way before turning around and returning and with a significant increase in speed.

“While scientists have found that this reverse rupture mechanism is possible on the basis of theoretical models, our new study provides some of the clearest evidence that this mysterious mechanism actually occurs,” Stephen Hicks said, lead researcher and seismologist of Imperial College London.

According to the analysis of seismic data, the 2016 earthquake had two separate phases.

First, the rip extended upward and eastward towards the weak point where the rip zone meets the Mid-Atlantic Ridge. Then, in a sudden U-turn, an “unusual westward propagation” occurred, with the tremors returning to the center of the fault and at significantly accelerated “super-shear” velocities of up to 6 kilometers per second.

“Even though the structure of the fault appears to be simple, the quake grew differently, and it was completely the opposite of how we expected the quake to look before we started analyzing the data.”

While the team’s explanation for how this boomerang unfolded remains speculative so far, the researchers speculate that the first, deep phase of the quake released enough fracture energy to initiate a reversal of the rift in the shallower, western underwater terrain.

“Either both sections of the fault were preseismically loaded enough to promote seismogenic failure, or the deeper SE1 fracture instantly increased static stress, immediately causing the shallower portion of SE2 to collapse,” the authors explain in their paper.

Although earthquakes propagating in the opposite direction have been studied by seismologists before, so far there has been little evidence of their existence, and this phenomenon is mainly observed in theoretical modeling.

Finding this type in the real world – in the middle of the ocean – is the first of its kind, not to mention the boomerang that returned at super shear speed.

“To my knowledge, this is the first time this has been reported,” geophysicist Yoshihiro Kaneko of GNS Science in New Zealand, who was not part of the research team, told National Geographic.

The results are reported to Nature Geoscience.

What has caused all these giant explosions and apocalyptic fires in China, North Korea, Lebanon, India, USA, Iraq, Iran over the past few days?

China

It all began on August 3, 2020 in the Chinese province of Hubei, where an instant explosion at a chemical plant killed at least six people and injured four. The reason is under investigation.

North Korea

This first explosion was followed a few hours later by a giant explosion following a possible “gas leak” in Hyesan, Yangan Province, North Korea, killing 9 people and injuring at least 30 residents. The reason is being investigated.

Lebanon

The next day, the port area of ​​Beirut, Lebanon, was destroyed by a giant explosion, killing more than 140 people and injuring thousands.

India

Also on the afternoon of August 4, 2020, an explosion caused panic among residents living around the Vijayshree Pharma Company plant in the Rambilli Zone FEZ in Vishakhapatnam in Andhra Pradesh, India. The reason is being investigated.

Great Britain

On 4 August, an explosion occurred again in the middle of a residential street in Birmingham, UK, causing smoke and fireballs to rise into the air and residents fleeing to seek refuge. The explosion was so strong that fire alarms went off in the houses.

United States of America

Finally, on Tuesday, firefighters put out a massive fire in downtown St. Paul, Minnesota, that engulfed a building under construction. When the firefighters arrived at about 4:20 am, the flames were flying high into the air, and the glow was visible for miles.

Iran

A fire broke out on Tuesday inside three industrial warehouses east of Tehran. The fire destroyed production materials, including lumber and leather.

Then, on August 5, at least seven ships burst into flames at a shipyard in the southern Iranian port of Bushehr. According to reports, the reason remains unclear, no casualties.

United Arab Emirates

On 5 August 2020, on Wednesday evening at 18:30, a fire broke out in a market in the emirate of Ajman, 50 km from Dubai, in the United Arab Emirates. The reason is being investigated.

China

A gas pipeline exploded and several roads collapsed after torrential rains flooded parts of Yulin, a city in China’s northwestern Shaanxi province. Local authorities evacuated about 600 people from the area. The reason is being investigated.

United States of America

On the same day in Midland, Texas, an investigation is under way of an explosion and subsequent fire in an oil storage facility. The reason is also unknown.

Iraq

Again, on August 6, 2020, a major fire broke out in over 20 wholesale market warehouses in Najaf, Iraq. The reasons are being investigated.

It is the largest study of DNA from people living in the Americas. It shows where the slaves came from in the United States and reveals the details of their abuse.

The work includes information on 50 thousand people, of which 30 thousand are of African origin. The article, published in the American Journal of Human Genetics , serves as “evidence that genetics can shed light on history,” said Alondra Nelson, professor of social sciences at the Institute for Advanced Study in Princeton.

The study began with the work of Joanna Mountain, senior director of research at the company 23andMe. Together with the team, she created a genetic database, which included mainly information about the company’s clients, whose grandparents were born in regions where slavery flourished. Dr. Stephen Micheletti, the geneticist at 23andMe who led the study, compared it to data from the Slave Travels digital project, which contains information about the people brought in: information on ports of embarkation and disembarkation, the number of enslaved men, women and children. He also collaborated with historians to learn more about the plight of African regions, such as contemporary Angola and the Democratic Republic of the Congo, in the 17th and 19th centuries.

Scientists have found out: the DNA of the study participants from the United States showed their Nigerian origin. This means that there are far more ships that transported enslaved people directly to America from Nigeria than would be expected based on historical records. 

At first, historians “could not believe how many Nigerian ancestors were there in the United States,” Micheletti said. 

Later, after consulting with experts, the study authors learned that slaves were first sent to the British Caribbean Islands, and only then sold to the Americans.

Experts estimate that more than half of the people were brought into the United States and Latin America from West Africa. The study found that the modern black population is genetically related to six regions, among them Senegal, Gambia, Nigeria and Benin. Moreover, according to historical sources, there were more regions from which slaves were exported.

The work also showed that the brought women made a much greater contribution to the modern gene pool than men, although there were much fewer of them. Scientists have calculated that in the United States there are 1.5 times more descendants of slaves, and in Latin America and the Caribbean – 13-17 times. Moreover, in the United States, European men have influenced the modern gene pool of people of African descent three times more than European women, and 25 times more in the Caribbean.