Earthquakes: Where could a big one hit next? – The Week

A large swath of the American Pacific Northwest is very likely to be hit by a major earthquake, though it may not happen for a while. A 2015 deep dive by The New Yorker examined the seldom-talked-about Cascadia Subduction Zone, which “runs for 700 miles off the coast of the Pacific Northwest, beginning near Cape Mendocino, California, continuing along Oregon and Washington, and terminating around Vancouver Island, Canada.” The zone is made up of two main tectonic plates, whose convergence forms the Pacific Northwest. These plates are “stuck, wedged tight against the surface” of one another, the magazine explained, and their movement could have the propensity to cause “the worst natural disaster in the history of North America.” However, for those in the area, it may be many years until a major rumble is felt. The Pacific Northwest Seismic Network (PNSM), which monitors fault line activity in the area, noted that “the last known megathrust earthquake in the Northwest was in January 1700, just over 300 years ago.” The PNSM said that geological surveys indicated earthquakes in the area had “a return interval of 400 to 600 years.” This means there may not be significant tectonic movement in the area for at least another 100 years. 

California is ripe for a major earthquake due to its location on the San Andreas Fault. This fault, which runs more than 700 miles and stretches across much of California, was reported by Forbes as being “likely to produce what could approach a magnitude 8 earthquake.” It’s “not a matter of if, but when a quake of roughly this size hits Southern California.” An earthquake of this scale would likely kill more than 1,800 people, injure 50,000 more, and cause up to $289 billion in damage, according to the California Earthquake Authority (CEA). However, there is obviously no set timeline for such an event. A report from the United States Geological Survey noted that the last major earthquake in the area was the 1906 San Fransisco shake. The report estimated that these types of earthquakes “occur at intervals of about 200 years,” adding that “there is only a small chance (about 2 percent) that such an earthquake could occur in the next 30 years.”  

Earthquakes often occur around the colloquial Ring of Fire, described by National Geographic as “a string of volcanoes and sites of seismic activity, or earthquakes, around the edges of the Pacific Ocean.” According to the outlet, more than 90 percent of all earthquakes on the planet happen along this ring. This puts two countries directly in their path: Australia and New Zealand. While serious earthquakes in Australia are rare, “their implications could be massive,” Australia’s The Saturday Paper wrote. The 1989 Newcastle earthquake devastated the city, killing 13 people and causing an estimated $18 billion worth of damage in today’s dollars. “At some point in the future, one of these magnitude five earthquakes will hit an urban center,” said Januka Attanayake, a researcher at the University of Melbourne. “We know that it’s going to happen, it’s just a matter of time.” New Zealand, meanwhile, has had many devastating earthquakes, including the 2011 Christchurch quake that killed 185 and caused widespread damage. Australia’s ABC News reported that research into the Alpine Fault, which traverses New Zealand’s South Island, “reveals a great earthquake, one of the biggest in New Zealand’s modern history, is due.” The last major Alpine earthquake was in 1717, and “it makes very big shifts, on average, about every 300 years.”