While much of the country was celebrating Valentine’s Day, a strong earthquake struck approximately 160 miles off Oregon’s coast and was felt as far south as San Francisco. What makes the magnitude-6 temblor of possible concern was both its magnitude and location.
Although nowhere near the strength of some of the truly large earthquakes that have shaken the globe in recent years, the quake nevertheless was one of the strongest ever recorded in or even near the state of Oregon and may suggest the seismically volatile region known as the Cascadia Subduction Zone could be emerging from an extended period of somnolence. Whether the Valentine’s Day temblor was a ‘foreshock’ to a much larger earthquake is not known, but in recent weeks a number of moderate quakes have struck the region.
Home to a complex meeting place of divergent tectonic plates, coastal Oregon – along with California’s San Andreas and Hayward faults and the New Madrid Seismic Zone – is considered prime territory for the U.S.’s next mega-quake. At the point where the quake occurred, the Juan de Fuca plate (the smallest of Earth’s tectonic plates) is being driven west into – and under – the North American continent. The resulting tension from these competing forces has been building for decades and seismologists warn that a major earthquake could result when the fault at last ‘slips.’
Indeed, there is growing evidence that coastal Oregon has been home to massive earthquakes and tsunamis similar to the ones that ravaged northeastern Japan last March. “The Pacific Northwest has the same kind of characteristics as the fault beneath Japan,” says James Gaherty, a seismologist at Columbia University’s Lamont Research Center.”We’re worried about a large subduction even similar to Japan.
Unfortunately, unlike Japan, which is one of the world’s most earthquake-prepared countries, coastal Oregon is nowhere near prepared for an earthquake of that magnitude. Despite all its preparations and early warning systems, Japan still suffered nearly 20,000 fatalities and the March 11 quake today ranks as the world’s most expensive disaster. A quake of a similar magnitude off Oregon could, by some estimates, kill 300,000 and devastate the region for years to come.