Latest news with #CentreNationald'ÉtudesSpatiales
Hindustan Times
3 days ago
- Science
- Hindustan Times
‘Mega' tsunami of Greenland in 2023 echoed for 9 days, shook sensors worldwide: NASA
A massive rockslide in Greenland in 2023 triggered a rare and persistent 'mega' tsunami that ricocheted within the steep walls of a remote fjord for nine days, according to new satellite data released by NASA and international researchers. The international Surface Water and Ocean Topography (SWOT) satellite mission, a collaboration between NASA and France's CNES (Centre National d'Études Spatiales), detected the tsunami's contours. The event, which unfolded in the Dickson Fjord in eastern Greenland, was captured by the Surface Water and Ocean Topography (SWOT) satellite — a joint mission between NASA and France's CNES — revealing never-before-seen details of how water surged and tilted inside the fjord after the impact. The landslide, which occurred in mid-September 2023, sent over 880 million cubic feet (25 million cubic meters) of rock and ice plunging into the Dickson Fjord, generating a tsunami that lacked space to dissipate. Instead, it bounced back and forth within the confined waterway — rising and falling every 90 seconds. The impact was so powerful that seismic sensors around the world detected the tremors. 'Far from the open ocean, in a confined space, the energy of the tsunami's motion had limited opportunity to dissipate, so the wave moved back and forth about every 90 seconds for nine days. It caused tremors recorded on seismic instruments thousands of miles away,' the article read. Using its high-resolution Ka-band Radar Interferometer (KaRIn), the SWOT satellite measured changes in water elevation from its orbit 560 miles (900 kilometers) above Earth. A flyover on September 17 — just a day after the landslide — showed dramatic tilting in water levels, with the north side of the fjord standing up to 4 feet (1.2 meters) higher than the south. These results were compared with baseline measurements taken weeks earlier, on August 6. 'SWOT happened to fly over at a time when the water had piled up pretty high against the north wall of the fjord,' the article quoted Josh Willis, a sea level researcher at NASA's Jet Propulsion Laboratory in Southern California. The Dickson Fjord, about 1.7 miles (2.7 kilometers) wide and 1,772 feet (540 meters) deep, lies along a remote network of channels on Greenland's rugged east coast. Its towering walls — more than 6,000 feet (1,830 meters) high — helped trap the 'mega' tsunami's energy and keep it churning for more than a week.
Yahoo
09-05-2025
- Science
- Yahoo
Could A New Big Wave Come from Underwater Mountains?
Cortes Bank, the famed and elusive wave 100 miles off the coast of California, is an anomaly. The massive peaks that have seen XXL records and near-death experiences result from a seamount — an underwater mountain with a summit below the surface. Now, scientists in a NASA-backed project say they've found up to nearly 56,000 previously unmapped underwater mountains in the planet's oceans. Mapping the ocean floor for numerous economic and environmental repercussions. Ships need to know if there are any hazards in their way. Cable-laying and mining operations have to know what's going on down there, too. Scientists are also interested in what kind of geological formations and marine ecosystems exist in the depths. The Surface Water and Ocean Topography project, a collaboration between NASA and the French space agency Centre National d'Études Spatiales, used radar altimetry during a full year of satellite observations. The SWOT satellite covered about 90% of the planet every 21 days, and the seafloor map it created was published in Science in December 2024. 'The SWOT satellite was a huge jump in our ability to map the seafloor,' David Sandwell, a geophysicist at Scripps Institution of Oceanography in La Jolla, California, told NASA. How big of a jump was this research? The satellite measured small 'bumps' on the ocean's surface caused by the subtle gravitational pull of the large seamounts below, and researchers used that data to predict the location of the underwater masses. According to their pencils, the number of mapped seamounts skyrocketed from 44,000 to nearly 100,000. That's an estimated 56,000 previously hidden peaks, uncovered just like is the next Cortes Bank still out there? Could another mountain range intercept swells and cause a titanic wave to break on the ocean's surface? Unfortunately, it's too soon to tell. This data is preliminary, and the SWOT team is still calculating the depths of each feature the satellite pinpointed. This is part of an international effort to map the entire ocean bottom by 2030. Previous research could only detect seamounts over 3,300 feet (1 kilometer) in height. The SWOT team can find features half that height. For reference, the Cortes range rises an estimated 4,000 feet from the ocean floor, and its tallest point (Bishop Rock) comes alarmingly close to the surface. It's also in a prime position to cop the brunt of massive long-period Pacific Ocean power. It's entirely possible the newly mapped seamounts don't come close enough to the surface to cause swells to break. While the scientists crunch the numbers, best keep your eyes peeled.
Forbes
31-03-2025
- Science
- Forbes
Researchers Just Found Thousands Of New Seamounts
Global map showing gravitational variations caused by topographic changes. In purple higher features ... More like seamounts and in green lower features like rift zones. There are better maps of the Moon's surface than of the bottom of Earth's ocean. Researchers have been working for decades to change that. As part of the ongoing effort, a NASA-supported team in collaboration with researchers from the French space agency CNES (Centre National d'Études Spatiales) recently published one of the most detailed maps yet of the ocean floor, using data from the SWOT (Surface Water and Ocean Topography) mission. Launched in December 2022, the SWOT satellite measures the height of water in lakes, reservoirs and rivers. Researchers can use these differences in height to create a kind of topographic map of the surface of fresh- and seawater. This data can then be used for tasks such as assessing changes in sea ice or tracking how floods progress down a river. SWOT covers about 90 percent of the globe every 21 days, so the researchers used the additional data to map the world's oceans. Elevations like underwater mountains, having a larger mass and a stronger gravitational pull, slightly deform the sea surface above them. Previous ocean-observing satellites have detected massive versions of these bottom features, such as seamounts over roughly 3,300 feet (1 kilometer) tall. The SWOT satellite can pick up seamounts less than half that height, potentially increasing the number of known seamounts from 44,000 to 100,000. 'Abyssal hills are the most abundant landform on Earth, covering about 70 percent of the ocean floor,' explains Yao Yu, an oceanographer at Scripps Institution of Oceanography and lead author on the paper. 'These hills are only a few kilometers wide, which makes them hard to observe from space. We were surprised that SWOT could see them so well.' The improved view from SWOT also gives researchers more insight into underwater plate boundaries, a key element in Earth's plate tectonics. The seafloor widens along rift zones, pushing the tectonic plates apart, and gets recycled into Earth's mantle along subduction zones. The orientation and extent of geological features mapped by SWOT can reveal how tectonic plates have moved over time. Rift zone in the Indian Ocean showing a parallel set of fracture zones and faults. Detailed seafloor maps have also practical applications. Accurate maps of the ocean floor are crucial for a range of seafaring activities, including navigation and laying underwater communications cables. The researchers have extracted nearly all the information on seafloor features they expected to find in the SWOT measurements. Now they're focusing on refining their picture of the ocean floor by calculating the depth of the features they see. The work complements an effort by the international scientific community to map the entire seafloor using ship-based sonar (hopefully) by 2030. The study, "Abyssal marine tectonics from the SWOT mission," was published in the journal Science. Additional material and interviews provided by Jet Propulsion Laboratory and NASA Earth Observatory
