Tag Archives: Mega

The Unpredictability of Mega Tsunamis: Understanding the Reasons Behind Their Threat

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On July 30th, at 12:25am BST (11:25am local time), a significant earthquake occurred off the coast of Russia’s Kamchatka Peninsula. With a magnitude of 8.8, it marked the sixth largest earthquake in recorded history, raising fears of a tsunami reminiscent of the 2004 Indian Ocean disaster.

Within hours, over 2 million individuals across the Pacific were ordered to evacuate as alerts reached coastlines from China and New Zealand to Peru and Mexico.

Fortunately, apart from some damage near the epicenter in Russia, the globe largely avoided catastrophe. As people heeded the warnings and moved to higher ground, many tsunami alerts were gradually downgraded and retracted.

The waves never materialized. But why?

How Tsunami Warning Systems Operate

The tsunami warning framework has significantly advanced since the devastating 2004 Indian Ocean tsunami, which claimed over 200,000 lives.

“Multiple tsunami warning centers exist globally,” said Professor Alison Raby, an environmental fluid mechanics expert at Plymouth University.

“These centers are alerted to earthquake incidents, determining their location, size, and depth—critical factors for predicting tsunamis. Consequently, they issue a broad alert based on this information.”

Given that seismic waves travel around 100 times faster than tsunamis, earthquake information reaches us well before the first wave. However, waiting to witness the tsunami is rarely feasible. By the time underwater pressure gauges or satellites detect unusual sea level changes, it may already be too late.

The detection speed varies based on the proximity of the source to the nearest detection system or coastal depth gauge, ranging from five minutes to two hours.

Utilizing data from past earthquakes and intricate computer models, scientists at warning centers often have limited time to decide whether to issue an alert, with the first warning typically released just five minutes after the ground stops shaking.

The final phase—communicating alerts effectively—has also improved since 2004. At that time, many coastal communities received little to no warnings. Now, emergency alerts can be sent directly to mobile phones, affording people crucial time to reach higher ground before the waves strike.

Data from surface water and oceanic topography (SWOT) satellites depict waves generated by the Kamchatka earthquake.

The Complexity of Tsunami Warnings

This year’s earthquake in Russia was categorized as a giant earthquake. Such occurrences transpire in subduction zones where one tectonic plate is thrust beneath another, leading to the most powerful earthquakes known.

As one plate descends, the other is elevated, causing the seabed to suddenly rise and displacing a substantial volume of water. This abrupt uplift triggers waves capable of traveling across the ocean basin, which grow larger as they approach the shallow coastline.

The Megathrust earthquake also caused the 2004 Indian Ocean earthquake and the 2011 Japanese earthquake, both of which generated towering tsunamis with waves exceeding 30m (100 feet). Therefore, it was no surprise that warnings were propagated throughout the Pacific.

The challenge lies in the fact that despite similarities in earthquakes, multiple factors influence tsunami generation.

“It’s not simply about detecting an earthquake and simulating potential tsunami sizes,” explained Liby. “Underwater landslides or other mechanisms may also play a role.”

The availability of data from specific locations is crucial. The same region in Russia experienced a magnitude 9 earthquake in 1952, yet remains underpopulated, leading to less comprehensive modeling efforts compared to other seismic hotspots.

Globally, records are limited. Reliable earthquake measurements only date back about a century, with only a few incidents generating tsunamis, resulting in an insufficient sample size for accurate predictions.

“We are fairly confident in understanding these events, but they always prompt new insights and questions,” affirmed Raby. “I am certain seismologists and seismic engineers will glean further knowledge from this recent incident that wasn’t previously recognized.”

The tsunami warning system has made significant strides. It’s now prioritized to er on the side of caution during tsunami evacuations rather than risk overlooking a potential disaster. Still, the balance is precarious.

“The issue is that people may become complacent,” noted Raby. “During evacuations, they may face income loss, or even car accidents, leading them to become skeptical of future warnings. Hence, the threat of excessive false alerts is real.”

Nonetheless, she remains hopeful. “I’m cautiously optimistic that improvements are being made, though we’re far from perfect forecasting capabilities.”

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Meet Our Experts

Allison Raby is a professor of environmental fluid mechanics at the University of Plymouth, UK. Her tsunami research has been published in peer-reviewed journals, including the International Journal of Disaster Risk Reduction and Marine Geology.

Source: www.sciencefocus.com

The Permian mass extinction could have been influenced by the Mega El Niño event

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Diagram of the end-Permian extinction event, where extreme temperatures may have caused forests to die off.

Richard Jones/Science Photo Library

The end-Permian extinction, 250 million years ago, may have been amplified by an El Niño event that was much stronger and longer-lasting than anything we see today.

These giant El Niño events caused extreme changes in the climate, wiping out forests and many land animals. Alexander Farnsworth At the University of Bristol, UK.

The El Niño also set off a feedback process that helped make this mass extinction so bad, he said: “There's a knock-on effect that's making these kinds of El Niños stronger and lasting longer.”

The end-Permian extinction is thought to have wiped out about 90 percent of all species living at the time, making it the worst mass extinction in history, and is widely thought to have been caused by a massive volcanic eruption in what is now Siberia.

These eruptions heated rocks rich in fossil carbon, releasing huge amounts of carbon dioxide, causing extreme global warming. Oceans became stagnant and oxygen-depleted, killing marine life.

But this doesn't explain the whole story: in particular, terrestrial species began to go extinct tens of thousands of years earlier than marine species.

A variety of ideas have been proposed to explain this, from volcanic winters to a disappearing ozone layer, but the idea that an extreme El Niño might be involved arose from studies of past ocean temperatures based on oxygen isotopes in fossils. Yadong Sun At China University of Geosciences in Wuhan.

Now, Farnsworth and his colleagues have run computer models to explore what might have happened at the end of the Permian period that could explain Sun's findings.

Currently, El Niño occurs when warm water in the western Pacific Ocean spreads eastward across the ocean surface, creating an area of ​​anomalously warm water that heats the atmosphere and affects weather across the globe.

The researchers found that before the Permian extinction began, El Niño events were probably similar in strength and duration to today, meaning abnormally warm waters were about 0.5°C (0.9°F) hotter than average and the event lasted for several months.

But these events occurred in a huge ocean called the Panthalassa, which was 30 percent larger at the equator than the present-day Pacific Ocean. This means that the area of ​​unusually warm water during El Niño was much larger than it is today, and its impact on the planet was much greater.

According to the team's model, rising carbon dioxide levels at the end of the Permian period caused El Niño events to become stronger and last longer. These events caused extreme weather changes on land and killed forests, which stopped absorbing carbon dioxide and started releasing it, leading to further warming and more extreme El Niño events.

In the ocean, the temperature changes would have been less drastic, and marine life would have had an easier time migrating to avoid them. This is why the marine extinctions occurred after more intense global warming. “The deadly extreme global warming that caused the marine extinctions was made worse by these El Niños because they stripped away carbon sinks,” says Farnsworth.

At the peak of the extinctions, El Niño temperature anomalies reached up to 4°C (7.2°F), and each event lasted for more than a decade, he says.

It's unclear whether a similar event will occur in the future — computer models vary in their predictions about how El Niño will change as the planet warms, Farnsworth said — but because El Niño occurs in a warmer world, it's already having big effects.

“The recent El Niño event has caused record temperatures and sparked a lot of wildfires,” he says, “and what worries me most is the signs of tree death in the Amazon during this El Niño event.”

Research shows that under certain climate conditions, El Niño could cause extinctions, Pedro Dinezio According to a team of researchers from the University of Colorado Boulder, such giant El Niño events don't occur today because the Pacific Ocean is smaller than the Panthalassa.

“These results are really interesting for understanding the past, rather than the near future,” Dinezio says. “To understand what El Niño will bring, we need to look at past periods when the continents were positioned similarly to the present.”

“I think this is a compelling study.” Phil Jardine Researchers at the University of Münster in Germany have discovered the first direct evidence that the ozone layer disappeared during the Permian mass extinction.

“I don't think this event and other extinction drivers, including ozone depletion, are mutually exclusive,” he says. “The scary thing about the end-Permian extinction is that a lot of things were happening at the same time, and they seemed to feed off each other in cascading ways throughout the Earth system.”

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Source: www.newscientist.com

SpaceX launches its Starship mega rocket from its Texas base

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SpaceX’s next-generation mega-rocket launched Thursday morning, roaring into orbit on an important test flight to demonstrate new technologies and techniques that will be important for future missions to the moon and beyond.

SpaceX said the flight was the rocket’s third and most ambitious test. The event was closely watched because the 400-foot-tall booster, known as Starship, is expected to play a key role in NASA’s plans to return to the moon.

The rocket lifted off at 9:25 a.m. ET from SpaceX’s Starbase Test Range in Boca Chica, Texas.

Approximately three minutes into the flight, the first stage booster, known as the Super Heavy, successfully separated from the Starship spacecraft above.

SpaceX plans to eventually make Starship a fully reusable vehicle, but that’s not the case with this test flight. Super Heavy is expected to fall to Earth and splash down in the Gulf of Mexico.

With this flight, SpaceX hopes to demonstrate that Starship can make a controlled re-entry into Earth’s atmosphere before splashdown in the Indian Ocean. Before its finale, the test also includes several different objectives from the rocket’s previous two flights. SpaceX will attempt to ignite one of Starship’s Raptor engines while in space, open and close the vehicle’s payload door, and transfer propellant between Starship’s two tanks in orbit.

Many of these technologies could help SpaceX run future missions to deploy satellites or prepare for lunar missions as part of NASA’s Artemis program.

Starship was selected by NASA to carry astronauts to the moon’s surface on the Artemis III mission, scheduled to launch in 2026.

Starship’s debut flight last April was a destructive one, ending with the rocket exploding minutes after liftoff. The second Starship launch in November achieved several milestones, including the separation of the first stage booster and upper spacecraft, but the company ultimately lost contact with the spacecraft.

Source: www.nbcnews.com