Thursday, March 10, 2016

Terrifying simulation shows how the Pacific Northwest could be decimated by a megaquake caused by the Cascadia fault

[Daily Mail] The threat of the ‘Big One’ has loomed over the Pacific Northwest for years.
A powerful earthquake thought to be as large as 9.2 magnitude ripped through the earth in 1700, along the 620 mile stretch of the Cascadia Subduction Zone, causing severe shaking and a massive tsunami.
Now, a terrifying new simulation from the Pacific Tsunami Warning Center has plotted the path of the tsunami as it traveled from the US to Japan.
Experts say an event of this kind occurs roughly every 400-600 years, and the area is now overdue for a similar quake that could leave thousands dead or displaced.
The historical tsunami struck the coasts of Japan just before midnight on January 27, 1700.
Scientists have finally traced the origins of this ‘orphan tsunami’ to a powerful seismic event in the Pacific Northwest of the United States, along the Cascadia Subduction Zone.
The researchers analysed sediment deposits and the ‘ghost forests’ of drowned trees, along with historical records from Japan and the oral histories of Native Americans, according to the PTWC.
Comparing the tree rings of dead trees with those still living allowed scientists to pinpoint the date of the last devastating earthquake.
The trees all died in the winter of 1699-1700, and the Pacific Northwest from Northern California to Washington suddenly sank up to 6 feet, flooding the area with seawater.
The animation from the Pacific Tsunami Warning Center, an effort by the National Oceanic and Atmospheric Administration and the National Weather Service, shows the real time path of the earthquake waves through the ocean, and what happens when the resulting tsunami waves hit land. 
Researchers call this a RIFT model, Real-Time Forecasting of Tsunamis.  
Using the earthquake information, the RIFT model shows movement, and predicts the speed, wavelength, and amplitude of the waves.
Wavelengths as well as height are indicated by colour.
The coastlines are all mapped with blue points at first, to represent normal sea level. 
As the tsunami waves reach them, the points will change colour to indicate the height of the incoming waves.
Blue to green points indicate no hazard, yellow to orange indicates low hazard, light red to bright red means significant hazard which requires evacuation, with waves of up to 10 feet, and dark red indicates severe hazard, with waves reaching heights over 10 feet.
In the severe hazard zone, a second-tier evacuation may even be necessary. Read More