{"id":547437,"date":"2026-01-27T19:11:12","date_gmt":"2026-01-27T19:11:12","guid":{"rendered":"https:\/\/www.europesays.com\/us\/547437\/"},"modified":"2026-01-27T19:11:12","modified_gmt":"2026-01-27T19:11:12","slug":"hidden-faults-discovered-at-a-major-us-earthquake-hotspot-sciencealert","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/us\/547437\/","title":{"rendered":"Hidden Faults Discovered at a Major US Earthquake Hotspot : ScienceAlert"},"content":{"rendered":"

Three huge tectonic plates meet at the Mendocino triple junction<\/a> off the coast of northern California, and a new study reveals that the underlying geology is significantly more complex than current models show.<\/p>\n

US researchers have run a new analysis of small, low-frequency earthquakes<\/a> recorded by seismometers across the Pacific Northwest, uncovering previously hidden faults.<\/p>\n

Their findings show that the triple junction is not composed solely of three plates, but effectively consists of five moving pieces.<\/p>\n

Related: Earthquake Sensors Detect Sonic Booms From Incoming Space Junk<\/a><\/strong><\/p>\n

That means earthquake prediction models<\/a> may need to be updated to give experts a better chance of estimating when the next big quake will hit. The discovery is analogous to analyzing the submerged portion of an iceberg, the researchers say.<\/p>\n

“You can see a bit at the surface, but you have to figure out what is the configuration underneath,” says<\/a> seismologist David Shelly, from the Geologic Hazards Center run by the United States Geological Survey.<\/p>\n

\"MendocinoThe updated model of the Mendocino triple junction. (Shelly et al., Science, 2026)<\/p>\n

As well as studying data from seismometers \u2013 which pick up subtle ground vibrations<\/a> from very small earthquakes that aren’t felt at the surface \u2013 the team also verified their field recordings using tidal-sensitivity models.<\/p>\n

The push and pull of the tides each day<\/a> cause small stresses on the underlying rock. By modeling these stresses to test how rocks respond, scientists can check that their interpretation of small, low-frequency earthquakes is correct, which in this case it was.<\/p>\n

A chunk of the North American plate<\/a> has broken off and is being pulled down with the Gorda (Juan de Fuca) plate<\/a>, the researchers determined. The team also confirmed the previously theorized existence<\/a> of the Pioneer fragment \u2013 a section of older rock being dragged underneath the North American plate.<\/p>\n

The North American plate, the Gorda plate, and the Pacific plate make up the Mendocino triple junction, with the Gorda plate being subducted<\/a> (pushed under) the North American plate, and absorbed into Earth’s mantle<\/a>. Crucially, the subducting surface is not as deep as previously thought.<\/p>\n

\"Audition<\/a><\/p>\n

This research shifts the most likely location of the plate boundary. The model is supported by a 7.2-magnitude earthquake that occurred in California in 1992<\/a>, which had an origin point at a much shallower depth than contemporary models would have predicted.<\/p>\n

“It had been assumed that faults follow the leading edge of the subducting slab, but this example deviates from that,” says<\/a> tectonic geodesist Kathryn Materna, from the University of Colorado Boulder.<\/p>\n

“The plate boundary seems not to be where we thought it was.”<\/p>\n

Related: ‘Megathrust’ Earthquake Could Trigger San Andreas Fault, Scientists Warn<\/a><\/strong><\/p>\n

Accuracy is crucial for predicting earthquakes, and that’s where this study will be most useful. Both the San Andreas fault<\/a> (where the North American and Pacific plates meet) and the Cascadia subduction zone<\/a> (where the Gorda and North American plates meet) can produce devastating earthquakes.<\/p>\n

\"YouTube frameborder=”0\u2033 allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share” referrerpolicy=”strict-origin-when-cross-origin” allowfullscreen><\/p>\n

There are a lot of moving parts to consider with the tectonic faults and earthquake zones of California and the western US seaboard, and scientists are working<\/a> to get the most comprehensive picture of them \u2013 so we can be as prepared as possible for what the ground is likely to do next.<\/p>\n

“If we don’t understand the underlying tectonic processes, it’s hard to predict the seismic hazard,” says<\/a> geophysicist Amanda Thomas, from the University of California, Davis.<\/p>\n

The research has been published in Science<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"Three huge tectonic plates meet at the Mendocino triple junction off the coast of northern California, and a…\n","protected":false},"author":3,"featured_media":547438,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[352,159,67,132,68],"class_list":{"0":"post-547437","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-msft-content","9":"tag-science","10":"tag-united-states","11":"tag-unitedstates","12":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115968651243047781","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/547437","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=547437"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/547437\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/547438"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=547437"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=547437"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=547437"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}