As well as sitting across several fault lines, Oregon would be seriously affected by a rupture of the Cascadia fault off the coast of California.
The Cascadia Fault is a subduction zone, an area where one of the tectonic plates is forced underneath the plate it collides into. In the case of Cascadia, the Juan de Fuca Plate is moving under the North American Plate. These plates have been locked together since 1700, 313 years. A particular feature of the Cascadia Fault is that it doesn’t produce small quakes, it remains still and silent until the pressure gets too much and one of the plates slips, giving rise to a mega-thrust earthquake of massive force. These quakes can be compared to the Indonesian quake of 2004 and the Japanese quake of 2011. (source)
A geologist with the Oregon Office of Emergency Management has likened the state to a full term pregnancy. Althea Rizzo, geology hazard coordinator for OEM said:
“We’re in the zone, and we’d darn well better get ourselves ready for it,”
Speaking at a meeting in Medford on Friday she continued:
“A lot of you may have moved here from California to escape them, but the fact is, Oregon is earthquake country.”
Rizzo said that there’s a 37% chance of the big one happening in the next 50 years, within the lifetime of many of those at the meeting.
A major earthquake would cripple transportation on Interstate 5 as bridges and overpasses collapse from two to four minutes of ground shaking, possible very severe, with stressful aftershocks for weeks. “It’s going to shake here,” she said. “Single-family homes will bounce off their foundations. Landslides will cause transportation between I-5 and (Highway) 101 on the coast to be cut off for three to five years.” A big quake will cause liquefaction, in which the ground, if saturated with water, will “turn to pudding,” causing hardware, such as sewer systems, septic lines and gas tanks, to rise up out of the earth. Lines from Washington state gasoline refineries cross 15 rivers, leaving them vulnerable to quake tremors, she says. Most of these were built in the mid-20th century, with no thought to making them quake-resistant, she says, adding that they would be offline for at least six months. Electrical power would be down from one to three months until transformers and the electrical grid get going again, she says.
She went on to explain that earthquakes cannot be predicted and that people residing in the state should be talking to friends and family about emergency plans and they should be taking first aid courses and Community Emergency Response Team Training.
Before the meeting closed she offered advice on home safety measures and advised people to store adequate food and water as well as getting to know who their neighbors are and what tools and training they have so that resources can be pooled in an emergency. (source)
It’s very likely that a tsunami would follow a quake caused by the Cascadia fault ‘unzipping’.
Within approximately 20-30 minutes the tsunami will roll in. Unlike normal waves which have a few yards between them the tsunami waves can have hundreds of miles between them. The entire wall of water displaced when the plates slip hurtles outwards in all directions from the epicenter of the quake. As the waves approach the continental shelf the water at the back of the wave starts to catch up with the water at the front of the wave, which has slowed down as it moves up the incline that marks the start of the continental land mass. Its this that allows the water to build up and give the tsunami its characteristic ‘wall of water’ appearance.
Those along the coast of Oregon should listen to the advice given to them in Medford, but they should also know the safest evacuation route to higher ground. All the earthquake drills in the world will not help you if you are faced with a 50 foot high wall of water.
All family members should be aware of the route and the meeting point. Everyone, even young children, should have a bug out bag. Small children can carry light but essential supplies such as granola bars and trail mix. Involving even very young children in the plans can lessen the fear and make them calmer.Tthey have a job to do and will follow instructions more readily if the reasons have been explained before hand.
Surviving an earthquake and tsunami is very challenging, but recognizing that should the Cascadia rupture a tsunami is almost certain to follow gives you a firm footing to plan from. Don’t wait and see. Subduction earthquakes come into the mega-thrust category, and there are rarely, very, very rarely foreshocks. These faults lie silent for decades, sometimes for centuries before they rip. The forces released are unimaginable as it has been building, unreleased since the last time it ripped, in the case of the Cascadia 1700. 313 years worth of tension that will distort and bend the sea bed. The displacement of water in the ocean above the rupture will send a tsunami out in all directions.
You will have 20-30 minutes to get to higher ground. Knowledge about you location, the terrain, the distance to higher ground will all impact your survival.
Read More about the Cascadia fault line here.
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Contributed by Chris Carrington of The Daily Sheeple.
Chris Carrington is a writer, researcher and lecturer with a background in science, technology and environmental studies. Chris is an editor for The Daily Sheeple. Wake the flock up!