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Thousands of previously undetected tiny earthquakes have revealed the edge of a miniature tectonic plate slamming into Alaska near the Denali Fault.The microplate could be focusing seismic energy in a straight line in a region under the Alaska Range of mountains, potentially contributing to large earthquakes and the development of small volcanoes in the area. The Yakutat microplate is an ocean plateau that is thicker than the Pacific oceanic crust surrounding it. Formed by volcanoes tens of millions of years ago, this block of crust is now being pushed under the North American Plate in Alaska in a process called subduction. But because it is thicker and more buoyant than the surrounding oceanic crust, the microplate pushes up the Alaska Range, which includes North America's highest mountain, Mount McKinley (also known as Denali). "Being able to identify where the Yakutat microplate is in the subsurface has helped us understand the tectonics," said Meghan Miller, the study's first author and a seismologist at the Australian National University. Study co-author Meghan Miller deploys a temporary seismic station. The data from these stations revealed a hidden microplate's location. (Image credit: Sarah Roeske.)Part of the plate is still off the coast of Alaska, sticking out like a slipper under a rug. But the precise location of the edge of the plate that has already subducted under the continent has been hard to pinpoint. Miller and her colleagues installed seven new seismometers south of the Denali Fault, which runs through the Alaska Range. This is a tectonically active region, most famous for a 2002 magnitude 7.9 earthquake that was felt as far away as Seattle. Related storiesThere's a massive fault hidden under America's highest mountain — and we finally know how it formed'New' island emerges from melting ice in AlaskaTectonic plates can spread subduction like a contagion — jumping from one oceanic plate to anotherBut it wasn't a giant temblor like 2002's that revealed the hidden edge of the Yakutat. Instead, it was unmasked by about 3,000 newly discovered minuscule earthquakes clustered in a clean line running from northwest to southeast for 155 miles (250 kilometers) under the Denali Fault. The "very sharp, linear pattern" also aligns with a series of small volcanic cones and rock-type changes in the deep subsurface, Miller and her colleagues reported in the new study, published June 4 in the journal The Seismic Record.The researchers suspect that the leading edge of the plate is focusing seismic energy toward the surface. The plate's location also aligns with the initiation point of the 2002 Denali quake, which started on a nearby fault, Miller told Live Science, but exploring that idea further will require computational modeling. "What we were postulating is that the edge of the Yakutat plate is influencing all these different types of processes," Miller said.

Researchers have found a new puzzle piece in Mars' geological history that hints that the Red Planet may have once harbored life. New data from NASA's Perseverance rover indicates that mudstones in Jezero crater contain a complex form of carbon, the chemical foundation of all known life. It's the highest concentration of organic molecules found on Mars to date. Although the mere presence of carbon isn't proof that life once evolved on Mars, the location of the discovery adds to the excitement. This "macromolecular carbon" was discovered near other potential signs of life, or biosignatures, touted by NASA with great fanfare in 2025. This geological context adds credence to the case that microbes may have once colonized the Martian surface. The results were published Wednesday (June 24) in the journal Science Advances.Perseverance landed in Jezero crater on Feb. 18, 2021. Since then, the site has emerged as one of the most geologically interesting places on Mars. "Jezero crater was once fed water and sediment from rivers, and, billions of years ago, it hosted a lake," Ashley Murphy, a researcher at the Planetary Science Institute and co-author of the new study, told Live Science in an email. It may have hosted more than that. A study published last year in the journal Nature found that some of the stones in an area of Jezero known as the Bright Angel outcropping contain clays and other minerals that are known to preserve fossils on Earth. One sample, in particular, raised eyebrows: a piece of a rock nicknamed Cheyava Falls, whose patterns resemble those left by terrestrial microbes. Although these patterns could have been created by nonliving sources, NASA officials proclaimed it one of the clearest signs yet of past microbial life on the Red Planet.The backbone of lifeThe new research builds on this work by confirming the widespread presence of complex carbon molecules in and around the Bright Angel outcrop. In the study, the researchers used the rover's Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to map the carbon distribution in these rocks and sediments. They compared them with carbon data from NASA's Curiosity rover taken at Gale crater some 2,300 miles (3,700 kilometers) away, a distribution that suggests water may have been widespread on Mars in the deep past. Murphy's team also determined that the carbon was not too weathered, indicating that it may have been exposed recently. However, it’s impossible to say whether the newly discovered carbon is related to life or not.The work is an important step in unraveling Mars' geological history, including the planet's potential habitability and how water shaped its surface. But Murphy cautioned that it is far from a definitive answer. "Macromolecular carbon on Mars does not prove the existence of life there," Murphy said. The molecules could indicate the presence of fossilized microbes, but they also could have formed through nonbiological means, like meteor strikes or running water. ‘Leopard spots’ on the rock formation Cheyava Falls could be linked to microbial life on Mars. (Image credit: NASA/JPL-Caltech/MSSS)Related storiesNASA rover discovers out-of-place 'Skull' on Mars, and scientists are baffledGiant string of organic molecules on Mars may be one of the best signs of life yetA giant 'shadow' has been creeping across Mars for 50 years — and scientists aren't sure whyUntil scientists get their hands on a sample directly, it will be hard to tell exactly how this complex carbon arose and whether it represents a true biosignature. But that research may now be decades away — if it happens at all. The Cheyava Falls sample was originally supposed to be brought to Earth in the 2030s as part of NASA and the European Space Agency's joint Mars Sample Return program. However, in its 2026 budget proposal, the Trump administration deemed the mission "financially unsustainable" and proposed slashing the project. Currently, the project is considered dead. It may be China that gets the first shot at bringing Martian samples back to Earth for analysis. The country's Tianwen-3 sample-return mission will aim to collect several samples — albeit in a more accessible but less-promising site than where Perseverance has looked for biosignatures — in a mission due to launch no sooner than 2028.What do you know about the Red Planet? Test your knowledge with our Mars quiz!