April 7, 2012
by John Vidale
This Monday, April 9th, Art Frankel (USGS, Seattle) will present scientists' best guess about the earthquake hazard for Seattle and the Pacific Northwest at a Seattle City Council hearing. The meeting is 9:30am in City Hall. Here is one summary.
These results arise from a series of workshops in Corvallis, Portland, and Seattle in the last year, culminating in a meeting at the UW in mid-March attended by more than 100 scientists, state emergency managers, and engineers. Art previously supervised construction of the US National Hazard Map, and is credited with putting USGS hazard mapping on a comprehensive, open, and conservative basis.
Some changes are notable. The Tacoma fault is joining the official club of dangerous faults. Although Art does not mention it, the danger of deep earthquakes like the M6.8 Nisqually event across southern Washngton and Oregon is likely to be re-evaluated. The danger of M8 to M8.6 events in southern Cascadia is likely to rise based on turbidite studies of Chris Goldfinger at Oregon State University. These three developments are redistributions of previous hazard estimates, not an overall rise in rates.
One likely change that would be a rise in hazard is being considered - given the 500-year recurrence of M9 earthquakes on our coast, the previous estimate contained a 1 in 500 chance of such an earthquake per year. However, from the observed regularity (and irregularity) of earthquake recurrence, and knowing that we haven't had an M9 for the last 312 years, the odds in a best estimate have risen 50%, so the next hazard map is likely to contain a 1 in 300 change per year of an M9.
Here is the entire set of slides. Art says he has been warned he won't have time to do it justice (which didn't stop him from overrunning by a factor of two his allotted time at a meeting in Portland yesterday).
The new maps are still undergoing review, and will not take effect for several years, so this is really a glimpse of likely future hazard estimates.
- Three Cascadia ETS events in past month??
- Is Mount St. Helens seismicity increasing?
- Warm weather triggers snow avalanches at St. Helens
- Seismic recordings of a gas explosion in North Bend, WA
- Seismic signals generated by the March 22nd Oso Landslide
- Legacy web site content returns
- Ice avalanches on Cascade volcanoes
- A New View On What's Shaking on the Cascade Volcanoes
- Seismic Spectrograms - A new way to look at wiggles
- The final football game analysis
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- 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)
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