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Debris Flow — Snohomish, Washington
March 22, 2014 · NOAA Storm Events record
Event narrative (NOAA)
On a warm and dry 22nd of March, 2014, a large landslide occurred four miles east of the town of Oso, Washington. The slide debris, traveling at over 60 miles per hour, crossed the entire river valley, covering an area of over a square mile with an approximate deposit thickness of 15 to 75 feet in some areas. The force of the slide flow caused 43 fatalities, 12 injuries, destroyed 37 homes, and wiped out SR 530 for over a mile. In addition, the slide debris completely blocked the North Fork Stillaguamish River for over 24 hours, backing up a pool of water that flooded the valley about 2 miles upstream and reached approximately 20 feet deep, inundating an additional 6 homes. The cause of the slide is not fully known, though precipitation in the previous months to years contributed to the gr
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Source: NOAA/NCEI Storm Events Database. Deaths and injuries are those NOAA classifies as direct. Damage is the reporting office's estimate at the time and is not inflation-adjusted. This is a catalogue record, not a forecast.