Latest news with #NorthAmericanPlate
Yahoo
15-04-2025
- Science
- Yahoo
Which active fault zones are in San Diego County?
(Above: Geologist Patrick Abbott, professor emeritus at San Diego State University, appears on FOX 5 to speak about the earthquake on April 14, 2025) SAN DIEGO (FOX 5/KUSI) — California is no stranger to earthquakes, but the risk of earthquakes hitting San Diego County specifically lies on the fact that it rests on multiple active faults. There are 15,000 known faults in the Golden State, according to the California Geologic Survey. San Diego County rests on four active faults — one of which is the San Andreas, one of the world's largest and most active fault zones. The San Andreas runs more than 800 miles long and divides the state into two tectonic plates, the Pacific Plate and the North American Plate. San Diego, Los Angeles and Big Sur are located on the Pacific Plate while San Francisco, Sacramento and the Sierra Nevada are on the North American Plate. Parts of San Diego County also lie in the Elsinore Fault Zone, which runs about 110 miles. According to the Southern California Earthquake Data Center, this fault zone is one of the largest in Southern California but historically has been one of the 'quietest.' The community of Julian rests on this fault, which is where two back-to-back earthquakes and several aftershocks occurred on April 13 and 14. According to the California Geological Survey, the Rose Canyon Fault Zone is part of the greater San Andreas Fault System. In San Diego County, it is partially responsible for the uplifted landscape of La Jolla and other coastal areas. It encompasses Mount Soledad and Point Loma in addition to the sea cliffs seen around La Jolla Bay and Torrey Pines. The San Jacinto Fault Zone is 130 miles long and includes Anza-Borrego Springs and the unincorporated community of Ocotillo Wells in east San Diego County. Other communities in this zone include San Bernardino, Loma Linda and Lytle Creek. The California Earthquake Authority — the publicly-managed insurance company created by state lawmakers after the 1996 Northridge earthquake — estimates there is a 99% chance of a magnitude 6.7 or greater earthquake striking the Golden State before 2044, based on 30-year models created by the U.S. Geological Survey in 2014. Landslides near Mount Soledad, Point Loma, Mission Valley and Sorrento Valley are expected to occur as a result of a major quake in these zones, the authority says. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
Yahoo
07-04-2025
- Science
- Yahoo
Uh, Looks Like North America is ‘Dripping' Into Earth's Mantle
Cratons are the most ancient, stable pieces of tectonic plates, but even these geological formations can change over time. A new study details how the North American plate is 'dripping' into the mantle due to the continued influence of the Farallon Plate, which has been subducting under the continent for 200 million years. While this 'dripping' is located beneath the U.S., it doesn't hold any consequences for us surface-dwellers. But it does provide a unique opportunity for scientists to study the formation—and disintegration—of continents. While there's often much to-do about tectonic plates, especially when their various subductions and transform sliding creates widespread devastation, cratons rarely nab the limelight. That's not because they're not unimportant—after all, they form the geologic core of all tectonic plates around the world. But as a result of being the most ancient pieces of Earth's lithosphere (containing the crust and uppermost mantle), they aren't subjected to nearly as much geologic dynamism as is found throughout the rest any particular plate. They're just kind of… there. However, recent research has shown that even these geologic stalwarts face incredible change over time. A study by Chinese scientists in October of last year detailed how one of the oldest pieces of continental crust—the North China Craton (NCC)—had slowly been disintegrating in a process known as 'decratonization' over the course of 200 million years. At the time, the author noted that the North American craton could experience similar deformations. Now, a new study published in the journal Nature Geoscience shows the deformation currently impacting the North American craton. Primarily located under the Midwest in the U.S., this craton appears to be 'dripping' into the mantle due to a subducting oceanic slab known as the Farallon Plate, according to researchers at the University of Texas at Austin (UT). What's fascinating about the North American craton's 'dripping' process—as opposed to the decratonization of the NCC, for example—is that this process is happening as we speak, which gives scientists an unprecedented opportunity to learn more about the geology of these lithospheric cores. 'We made the observation that there could be something beneath the craton,' Junlin Hua, the lead author of the study who is now a professor at University of Science and Technology of China, said in a press statement. 'Luckily, we also got the new idea about what drives this thinning.' By creating a full-waveform tomographic model of the North American plate using seismic data gathered from the EarthScope project, Hua and his team were able to spot this 'dripping' behavior far beneath the Earth's surface. The main engine behind the dripping (shown in the image above) is the Farallon Plate—an oceanic plates that's been subducting under the North American Plate for 200 million years, and has played a starring role in shaping the continent. The researchers theorize that this plate is impacting the craton by redirecting mantle flow, while also releasing volatile compounds that wear away the base of the plate. Of course, this doesn't mean that the Midwest will suddenly sink into an abyss. In fact, the researchers estimate that this 'dripping' will eventually end as the Farallon Plate continues to sink into the mantle and its influence on the craton wanes. 'This sort of thing is important if we want to understand how a planet has evolved over a long time,' Thorsten Becker, a co-author of the study from UT, said in a press statement. 'It helps us understand how do you make continents, how do you break them, and how do you recycle them [into the Earth.]' Who says cratons can't be exciting? You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
