Hidden earthquake risk found lurking beneath Los Angeles
The ports of Los Angeles and Long Beach bustle with activity—their colorful array of shipping containers are stacked and unstacked in a never-ending, multibillion-dollar game of Tetris. But a previously overlooked danger lurks below this frenzy: A fault capable of generating earthquakes magnitude 6.3 or greater.
The Wilmington fault, as it’s called, is an elusive type of fracture. Unlike many faults, which crack Earth’s surface like an egg, the Wilmington fault is “blind,” which means it’s concealed beneath the surface, making it especially difficult to study. So while scientists have long known the fault is present—stretching 12.4 miles under southern Los Angeles into San Pedro Bay—it was presumed to have sat quiet for millions of years.
Now, a new analysis of the system, published in Bulletin of the Seismological Society of America, suggests that isn’t the case. Using a cluster of clues incorporated into a three-dimensional model, the study authors posit that the fault has been active much more recently than once thought—and likely still poses a risk to people on the surface.
“I hope bringing attention to it can potentially increase safety in the region,” says study author Franklin Wolfe, a doctoral candidate who is part of Harvard’s structural geology and Earth resources group.
While the fault is slow moving and likely ruptures only once every 3,200 to 4,700 years, it underlies two of the United States’ busiest ports. And researchers worry that the Wilmington could link with other nearby faults to produce a temblor as strong as a magnitude 7.4.
https://www.nationalgeographic.com/science/2019/08/hidden-earthquake-risk-discovered-under-los-angeles/?cmpid=org=ngp::mc=crm-email::src=ngp::cmp=editorial::add=Science_20190911&rid=FB26C926963C5C9490D08EC70E179424