December 19, 2011
by Kate Allstadt
Landslides and seismology are two words not often associated with each other. However, in the case of the Nile Valley Landslide of October 11, 2009, the two went hand in hand. The landslide, one of the largest in recent Washington State History, involved more than 10 million cubic meters of material. It destroyed several houses, a portion of Highway 410 and partially dammed a river, causing flooding in the valley. The photo below shows where the landslide crossed Highway 410.
A portion of the riverbed was uplifted near the toe of the slide and was later found on top of the toe along with some unsuspecting dead fish. Fortunately, the fish were the only casualties because the landslide gave warning in the days and hours beforehand: rumbling sounds, raveling rocks and a smaller precursory landslide. These "foreshocks" allowed people to evacuate in time. As the main landslide failed in a complex series of events, some of the more energetic failures generated signals that were detected on two seismic stations operated by the PNSN nearby. In collaboration with the WA Department of Transportation and Department of Natural Resources, PNSN seismologists pieced together the timeline of sliding events using the seismic record in combination with eyewitness accounts and site investigations. Click the image below to enlarge the timeline:
They also deployed seismometers around the landslide to monitor post-slide seismicity. They recorded more than 60 "aftershocks," smaller landslides that were primarily small landslides off of the newly created and very unstable headscarp. The dashed line on the LIDAR image below outlines the extent of the landslide, the triangles are the seismic stations the PNSN installed after the landslide, and circles are the approximate location of the "aftershock" landslides the PNSN was able to locate.
- Why earthquakes disappear
- PNW Earthquake Early Warning prototype goes live
- Packers versus Seahawks game analysis -- too exciting
- Panther versus Seahawk Game Analysis
- Seismology will again watch/help the Seahawk's playoff run
- Canadian ETS morphing to Washington one?
- Great ShakeOut, Great success!
- The Great ShakeOut 2014 is Tomorrow!
- Three Cascadia ETS events in past month??
- Is Mount St. Helens seismicity increasing?
- 2015 (5)
- November (1)
- October (2)
- September (1)
- July (1)
- May (1)
- April (1)
- March (2)
- February (3)
- January (4)
- October (1)
- September (1)
- August (1)
- June (1)
- April (3)
- March (4)
- February (1)
- January (2)
- December (1)
- November (2)
- October (3)
- September (1)
- August (3)
- July (2)
- June (4)
- May (4)
- April (2)
- The wech-o-meter takes over all of Cascadia
- Keystone Cops: Italy prosecutes seismologists for failure to predict deadly quake
- UFOs in eastern Washington? No, rather UTEs (Unidentified Terrestrial Events)
- New Sodo Seattle Liquefaction Array Installed
- Why we should constantly watch the deformation of the seafloor
- Mystery chirp near Newberry Volcano
- Planting seismographs causes earthquakes? or maybe ice-quakes?
- Tunneling rumbles south under Capitol Hill
- 15 years of mostly silent magma inflation near Three Sisters, Oregon
- Mount Hood earthquake swarm of Feb 23, 2012
- Web glitches: duplicate (and even triplicate!) earthquakes
- How earthquake magnitude scales work
- Mine blast masquerades as volcanic tremor
- The Spokane Swarm about 10 years ago
- Another hum around Mount St. Helens
- Slow slip: A new kind of earthquake under our feet
- PNSN and social media
- 3am M3.4 earthquake in St. Helens Seismic Zone
- The wrong kind of volcano noise
- Fast chatter on Rainier an hour ago
- Can slush-mageddon trigger earthquakes?
- Rainier Repeating Earthquakes Update and Comparison with Weather Patterns
- 22-minutes drumbeat icequakes(?)
- Mount Rainier popping away
- Repeating Earthquakes on Mount Rainier - are glaciers the culprit?
- Debunking another SEC football myth by the PAC-12
- One year ago, Seattle Seahawks 12th Man Earthquake
- The odds this year of a megaquake on the Pacific Northwest coast
- Is the plague of great earthquakes this decade a sign of increased danger?
- Nile Valley landslide talks to PNSN seismologists
- Good vs evil in central US earthquake hazard analysis
- Why does a volcano scream?
- Predicting big quakes from patterns of little ones
- 1-hour warning for Japanese M9 earthquake?
- Sound Transit train under Interlaken keeps a rollin'
- Invisible changes under the hood at the PNSN
- Sound Transit Tunneling Noise
- "Visionary" toads
- Earthquake early warning in the PNW
- November (1)
- December (13)