Plenty of enemy encounters feel like the high enemy counts merely ended up prolonging them rather than presenting a greater challenge. "Quantifying crust-to-mantle connections along major strike-slip faults is critical for understanding linkages between deep fluid flow, seismicity and fault healing," Newell says.Very repetitive, very little variety in encounter design, poorly communicated instant death traps, and the secrets are laughably easy (they do get better later on, but barely). These types of faults host large, devastating earthquakes, such as February 2023's deadly earthquake on the East Anatolia Fault, which caused widespread destruction in Turkey and Syria. The fault's mantle fluid flow rates fall in the range observed for the world's other major and active strike-slip faults that form plate boundaries, he says, including California's San Andreas Fault and Turkey's North Anatolian Fault Zone. "This is important as it reveals mantle-to-surface volatile flux and how fluid pressure gradients may impact fault strength and seismicity along the fault." "That's the 'speed limit' part of our research," Newell says. The geoscientists also seek data on how fast helium can move from the mantle to the crust along active faults. "These bubbling springs are indicative of the possibility of a future large destructive earthquake along the Denali Fault segment near Denali National Park, which receives some 600,000 visitors each summer." "The last major earthquake on the Cantwell segment was 400 years ago, and the helium data suggest those mantel connections have been reestablished," Newell says. These observations, he says, have implications for how groundwater pathways along the fault are changed by earthquakes, and the timescales on which they heal. In contrast, springs along the ruptured fault segment only have atmospheric gases, suggesting a 'roadblock' preventing the flow of mantle helium to the surface." "Warm, bubbling springs west of the 2002 earthquake rupture, along the Cantwell segment of the Denali Fault, have a strong helium-3 signature, indicating intact connections to the mantle. "Helium-3, a rare isotope of helium gas, in springs is a good indicator of whether or not an area has a connection to the Earth's mantle," Newell says. To examine these possible deep connections, Newell and Regan sampled 12 springs along the Denali and Totschunda Faults, by way of helicopter and on foot, to the remote, mountainous regions of Alaska's interior. "But we don't know much about how and if these connections are maintained." "Active strike-slip faults like Denali have three-dimensional geometries with possible deep conduit connections below the Earth's surface," Newell says. The research was funded by a one-year National Science Foundation Early-Concept Grant for Exploratory Research (EAGER) awarded to Newell and Regan in 2020. He and colleagues Jeff Benowitz, an Alaska-based geochronologist, Sean Regan of the University of Alaska Fairbanks, and doctoral candidate Coleman Hiett of USU, collected and analyzed helium and carbon isotopic data from springs along a nearly 250-mile segment of the fault and published their findings, "Roadblocks and Speed Limits: Mantle-to-Surface Volatile Flux in the Lithospheric Scale Denali Fault, Alaska," in the Jprint issue of the journal Geology. Understanding the restless fault's mantle-to-crust connections provides critical information for understanding the lithospheric-scale fault's seismic cycle, says Newell, associate professor in USU's Department of Geosciences. "It's a big, sweeping fault and the source of a magnitude 7.9 earthquake in 2002, that ruptured more than 200 miles of the Denali Fault, along with the Totschunda Fault to the east, causing significant damage to remote villages and central Alaska's infrastructure," says Utah State University geochemist Dennis Newell.
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