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Scientists see an earthquake boomerang back and forth in the Atlantic

Seismic data from 2016 reveals a rare bi-directional boomerang earthquake.

Credit: Hicks et al., published in Nature Geoscience / © Imperial College London
  • An earthquake ran quickly east before turning west beneath the Atlantic Ocean near the equator in 2016.
  • Such earthquakes are likely to pack significantly more destructive power.
  • Land-based boomerang earthquakes may have been witnessed, but have never been recorded seismographically.

It was definitely an odd story Rosario García González told in the summer of 2010.

González is an elder of the indigenous Cucapah community in Baja, California/Mexico. He and his wife were in their trailer in Paso Inferior, about 12 miles south-southwest of Mexicali when they heard and felt the distinct, powerful rumble of earthquake moving across their valley. Looking outside, they watched as a cloud of light-colored dust was thrown up into the air along a path going in the opposite direction, as if a truck was retracing the earthquake's path. Except there was no truck.

It's not that scientists didn't believe González's story — they just couldn't figure out what he saw. Could an earthquake possible boomerang? The answer appears to be yes. A new study of seismic data has found clear evidence of another boomerang earthquake — technically a "back-propagating supershear rupture" — that shot back and forth deep beneath the Atlantic Ocean in 2016.

Boom and back

Reconstruction of Romanche fracture zone

Reconstruction of Romanche fracture zone

Credit: Hicks et al., published in Nature Geoscience / © Imperial College London

The research was conducted by scientists from the University of Southampton and Imperial College, London in the U.K. First author Stephen Hicks of Imperial College says, "Whilst scientists have found that such a reversing rupture mechanism is possible from theoretical models, our new study provides some of the clearest evidence for this enigmatic mechanism occurring in a real fault."

The 2016 magnitude 7.1 quake occurred along the Romanche fracture zone — this is a 559 mile-long fault line near the Atlantic equator, about 650 miles west of the coast of Liberia.

Speaking to National Geographic, Hicks recalled the discovery of what at first seemed like a pair of pulses, which closer examination indicated might actually be two phases of the same quake. If so, the quake zipped eastward, and then west. "This was a weird sort of configuration to see," he says. Confirmation of the boomerang was provided by Ryo Okuwaki of Japan's University of Tsukuba via the identification of seismic echoes from the distant event.

"Even though the fault structure seems simple, the way the earthquake grew was not, and this was completely opposite to how we expected the earthquake to look before we started to analyse the data," admits Hicks.

When modeled, the data collected by 39 seismometers arrayed along the bottom of the ocean-floor gash depicted a temblor that moved rapidly in one direction before suddenly turning around and going back in the other at a blistering 11,000 miles per hour. This likely caused seismic waves to pile up similarly to what happens with air-pressure waves trigger a sonic boom, significantly magnifying the quake's power.

Land boomerangs

Rosario Garc\u00eda Gonz\u00e1lez (left) points to where earthquake happened

Rosario García González points to where the earthquake doubled back.

Image source: CISESE/USGS

While it's logistically simpler to record and study earthquakes on land thanks to the availability of seismometer networks, land-based temblors tend to track complex fault systems, with geological slips occurring in a series like falling dominoes. Sea-bottom quakes appear to be simpler, making it easier to discern their underlying mechanisms and travels.

Only a few boomerang quakes have ever been recorded, and examples of them on land are virtually nonexistent, making accounts such as González's that much more valuable. Clearly, quakes that double back on themselves stand to do considerably more damage than one-way shakers, allowing more outward propagation of destructive seismic waves in the direction of travel, an amount that would be doubled in a boomerang. Seismologist Kasey Aderhold tells National Geographic that "studies like this help us understand how past earthquakes ruptured, how future earthquakes may rupture, and how that relates to the potential impact for faults near populated areas."

Scientists developing computer models aimed at predicting seismic events haven't thus far been able to create worthy simulations of boomerang quakes, so the details provided the U.K. researchers provide some of the best information yet collected on these geologic oddities.

Scientists have revived 100-million-year-old marine microbes

In one of the ocean's most lifeless places, scientists discover and resuscitate ancient organisms.

Image source: Morono, et al
  • Seemingly dead microbes from 100 million years ago spring back to life.
  • The microbes were buried deep beneath the Pacific's "Point Nemo."
  • There's crushing pressure beneath the seabed, but these microbes apparently survived anyway.

There is a place in the South Pacific that's as far as you can get from land. This "oceanic pole of inaccessibility" lies beneath the South Pacific Gyre that covers 10 percent of Earth's ocean surface. It's so remote that spacecraft are regularly guided down into its waters at the end of their missions. Says NASA, "It's in the Pacific Ocean and is pretty much the farthest place from any human civilization you can find."

There's another reason, though, that this so-called "Point Nemo" isn't like anywhere else. It's an oceanic desert, about as devoid of standard marine life as any stretch of water can be. Nutrients from land can't reach it, and currents keep its waters isolated from the rest of the ocean. There's also an excess of ultraviolet light out there.

While there is some microbial life floating in the area, a team of scientists from Japan and the U.S. wanted to know if anything could possibly be living in the area's desolate seabed. What they found and retrieved were seemingly lifeless microbes trapped down there for 100 million years. It turns out that the tiny organisms are still alive after all this time —all they needed was food and oxygen.

"Our main question was whether life could exist in such a nutrient-limited environment, or if this was a lifeless zone," says study leader microbiologist Yuki Morono of the Japan Agency for Marine-Earth Science and Technology. "And we wanted to know how long the microbes could sustain their life in a near-absence of food." Apparently hundred of millions of years. Take that, tardigrades.

The research in published in the journal Nature Communications.

Deep surprise

Map showing Point Nemo in Pacific Ocean

Image source: martinova4/vector illustration/Shutterstock/Big Think

It's hardly a hospitable environment down there, and the weight of all that water above presses down hard on anything beneath it. Organisms trapped under this kind of pressure typically die and fossilize, given a million years or so. Still, for some reason, these microbes evaded that fate.

Co-author Steven D'Hondt, a geomicrobiologist from University of Rhode Island, says, "We knew that there was life in deep sediment near the continents where there's a lot of buried organic matter. But what we found was that life extends in the deep ocean from the seafloor all the way to the underlying rocky basement."

Onboard study

Morono (left) and D'Hondt (right) examining cores aboard JODIES Resolution.

Image source: IODP JRSO/University of Rhode Island

The microbes were brought up through 3.7 miles of water from the ocean bottom during the JOIDES Resolution drill ship's 2010 expedition to the Gyre. The researchers extracted samples from an array of sites and depths, including pelagic clay sediments as deep as 75 meters (246 feet) beneath the sea floor.

Examining the sediment cores on the ship, the researchers found small numbers of oxygen-consuming microbes in every sample from every depth. The samples were removed from the cores to see if their occupants could be resuscitated. They were given oxygen and their presumed food of choice, substrates of carbon and nitrogen, by syringe. The samples were then sealed in glass vials and incubated.

microbe growth charts

Growth of microbes after being fed carbon (top) and nitrogen (bottom)

Image source: Morono, et al

Vials were opened after 21 days, 6 weeks, and 18 months. Stunningly, up to 99 percent of the microbes were revived, even those from the deepest — and thus oldest — cores. Some had increased 10,000 times their number, consuming all of the carbon and nitrogen they'd been given.

The scientists could hardly believe what they were seeing. "At first I was skeptical, but we found that up to 99.1 % of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat," recalls Morono.

A bottomless research opportunity

"It shows that there are no limits to life in the old sediment of the world's ocean," says D-Hondt. "In the oldest sediment we've drilled, with the least amount of food, there are still living organisms, and they can wake up, grow and multiply."

Some have suggested that the microbe may be more recent descendants of their 100-million-year-old ancestors, but D'Hondt says there isn't enough in the way of nutrients or energy down there to support cell division. That is, unless there's some other form of energy that has been overlooked, say, some form of radiation. "If they are not dividing at all, they are living for 100 million years, but that seems insane," he says.

'A world with no ice': Confronting the horrors of climate change

The complacent majority needs to step up and call for action on climate change.

  • Climate change is often framed as a debate that has split society down the middle and that requires more evidence before we can act. In reality, 97 percent of scientists agree that it is real and only 3 percent are skeptical. A sticking point for some is the estimated timeline, but as Columbia University professor Philip Kitcher points out, a 4-5 Celsius temperature increase that makes the planet uninhabitable is a disaster no matter when it happens.
  • In this video, 9 experts (including professors, astronomers, authors, and historians) explain what climate change looks like, how humans have already and are continuing to contribute to it, how and why it has become politicized, and what needs to happen moving forward for real progress to be made.
  • David Wallace-Wells, journalist and New America Foundation National Fellow, says that the main goal of climate action is not to win over the skeptical minority, but to "make those people who are concerned but still fundamentally complacent about the issue to be really engaged in a way that they prioritize climate change in their politics and their voting and make sure that our leaders think of climate change as a first-order political priority."
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Polar bears could be extinct by 2100, says heartbreaking new study

If Arctic ice continues to melt at its projected rate, the bears will go extinct due to starvation by the end of the century according to a first-ever projected timeline.

  • A new report on climate change by the University of Toronto is projecting that most of the polar bear population could reach extinction in under 100 years due to starvation.
  • Polar bears are dependent on sea ice for hunting seals, a primary component of their diet. As temperatures rise and sea ice continues to shrink it has become increasingly challenging for the carnivores to hunt for food.
  • The Arctic is likely to have warmed more than double the amount of the global average this year compared to pre-industrial temperatures.
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Scientists find 16 'ultra-black' fish species that absorb 99.9% of light

These alien-like creatures are virtually invisible in the deep sea.

Credit: Karen Osborn/Smithsonian
  • A team of marine biologists used nets to catch 16 species of deep-sea fish that have evolved the ability to be virtually invisible to prey and predators.
  • "Ultra-black" skin seems to be an evolutionary adaptation that helps fish camouflage themselves in the deep sea, which is illuminated by bioluminescent organisms.
  • There are likely more, and potentially much darker, ultra-black fish lurking deep in the ocean.
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