"Other active crustal faults exist in the Portland Metropolitan Region, but a rupture on the Portland Hills fault would be the most impactful, given its position directly underneath downtown Portland and the population centers of Clackamas County," the report reads.If a magnitude 6.8 quake were to strike this fault, 23 to 32 percent of the 615,000 buildings in the study area could be lost with damage estimates ranging from $60 billion to $83 billion.
The Portland Hills Fault, which runs from Oregon City to Scappoose, sits directly under some of the city's most important infrastructure and densest population centers. The 3,076-square-mile study area, which includes Multnomah, Clackamas and Washington counties, is also home to all of Oregon's major liquid fuel port terminals and the state's largest airport. If that quake were to strike at 2 a.m., the area would see between 16,000 and 29,000 casualties, again ranging from minor injuries to fatalities. Some other subduction zones have such earthquakes every 100 to 200 years; the longer interval results from slower plate motions. A shaker in winter, when topsoil is likely to be wet and prone to landslides, could be worse than one during dry months.The last major rupture of the Cascadia Subduction Zone was in January of 1700.The last time the whole Cascadia Subduction Zone ruptured was January 26, 1700, more than 300 years ago, and at least 40 large-magnitude earthquakes have occurred along the fault in the past 10,000 years. Author: Glenn Farley Published: 9:38 … A major earthquake in the Portland area could cause more damage and a higher number of casualties than previously thought, according to a new study.For the first time in 20 years, Portlanders are getting a detailed look at the damage that will be caused by a catastrophe we all know is coming — a major earthquake striking the metro area — and the prospects are grim. A southern Big One would likely strike a little further away from the heart of Los Angeles, so the impact might be smaller.
"Seismic upgrades to buildings, or replacement of older buildings, can significantly reduce loss and casualties," the report said. An earthquake during the day, when most people are out and about, could be worse than one in the middle of the night.
Medical facilities are likely to overburdened with serious injuries after a major quake and otherwise hobbled by power loss and emergency transportation routes that could be impassable.Douthit also pointed to the development of an early warning system for earthquakes, which is still in the testing phase. Earthquake damage at Molalla High School following the Spring Break Quake in 1993. All of those critical pieces of infrastructure, as well as the 1.6 million people who live in the region, would be affected by a major earthquake.Not every earthquake is the same, however, and the report laid out a few different scenarios for what could be waiting for Portland and the surrounding area.The earthquake that Pacific Northwesterners have long known about and feared is one caused by a rupture of the Cascadia Subduction Zone, the 600-mile-long fault that sits ominously off the west coast, running from Northern California up to Vancouver, B.C.The subduction zone, and the danger it poses, was cast into stark relief by The fault is divided into sections, each of which could produce a moderate quake, but the report is modeled for the so-called "big one," in which the whole fault slips and a massive magnitude 9.0 temblor shakes the entire region.But the fault buried under the ocean is not the only one that threatens the metro area. "Although damage estimates vary widely throughout the study area, no community will be unharmed," the report said.While the Cascadia Subduction Zone has garnered more public attention in recent years, the lesser-known Portland Hills Fault has the potential to cause more damage, according to the report, though it is far less likely to occur.While the subduction zone has seen some 40 major quakes over the last 10,000 years, the Portland Hills Fault is thought to have only produced two sizable seismic events over the last 15,000 years. "The damage estimates are significantly higher than those given in previously published studies for the area," the report states, as it uses better data about the buildings in the metro area, many of which were built using unreinforced masonry.
The most important clue linking the tsunami in Japan and the earthquake in the Pacific Northwest comes from studies of tree rings (Sediment layers in these locations demonstrate a pattern consistent with seismic and tsunami events around this time.Some of the stories contain temporal clues — such as an estimate of how many The geological record reveals that "great earthquakes" (those with Kenneth Murphy, who directs FEMA's Region X, the division responsible for Oregon, Washington, Idaho, and Alaska, put it quite dramatically: "Our operating assumption is that everything west of Recent findings conclude that the Cascadia subduction zone is more complex and volatile than previously believed. When the 'Big One' hits, Portland faces mass casualties, widespread destruction: Study Updated Jan 30, 2019; Posted Mar 15, 2018 Earthquake damage at … Some 26 to 34 million tons of debris would be created and between 96,000 and 257,000 people would face long-term displacement. Having a well-stocked earthquake kit is a good place to start.The Portland Bureau of Emergency Management has been working to train a cadre of volunteers under the moniker That last point will take on special significance in a mass casualty event, Douthit said, as it will keep those with minor injuries from flooding to emergency rooms.
Vast swaths of Portland's west side, a large stretch of the south bank of the Columbia River and portions of the city's inner east side are all at high risk of liquefaction or landslides, especially if the quake strikes during the wet winter months, the report said.A map of the metro area shows which areas are susceptible to liquefaction and landslides during a major earthquake. Between 9 and 14 percent of the buildings in the area, which number more than 600,000, would be lost. No one can say when exactly the next Cascadia megaquake will strike other than there's a fair chance it'll happen in our lifetimes. Another 1,600 structures are built of unreinforced masonry, Douthit said, and are particularly vulnerable to shaking.