The BIG One

Corvallis, Ore. is in the middle of a fault line consisting of two tectonic plates that will cause an earthquake known as ‘The Big One’.

Experts say this big one will occur within the next 100 years and predicted to be one of the biggest earthquakes the Pacific Northwest has seen since 1700. There have been at least 32 of these big earthquakes in the last 10,000 years.

Dean of College of Engineering at Oregon State University, Scott Ashford, who has a PhD in geotechnical engineering, has documented past earthquakes and calculated what will happen in the future.

“It is a very slow moving boundary. What that means is that stress builds up over a long period of time,” Ashford said. “When that stress builds up to a certain point there is an earthquake, the shifting plates can generate up to a magnitude 9 earthquake or more.”

Ashford said the biggest earthquake ever recorded in the world was about a 9.5 magnitude on the Richter scale. This scale measures the amount of energy that is released from an earthquake, the highest ever recorded being in 1906 in San Francisco at a 8 magnitude. 

“I have heard that you will be able to feel it as far as Salt Lake City from the Oregon coast,” Ashford said.

Andre Barbosa, associate professor in Civil Engineering, said there is a 15 percent chance that this earthquake will happen within the next 50 years.

“This is a higher probability than buildings are designed for today,” Barbosa said. “From the structural engineering side we are not prepared for this. 80-85 percent of (Oregon’s) infrastructure has been built prior to us even having knowledge of this earthquake.”

For this earthquake the most shaking will be along the coast with some damage going as far as Central Oregon, Ashford said.

Erica Fischer, assistant professor in civil and construction engineering at OSU has participated in earthquake reconnaissance, where she was able to go to locations directly after an earthquake to survey damaged buildings and infrastructure.

 Fischer said for many earthquakes that occur in places like the crustal faults, earthquake shaking typically lasts for 30 seconds. Whereas subduction zone earthquakes can have strong shaking for more than three minutes.

 “We predict about three minutes of shaking will occur when it hits,” Fischer said.

Many buildings cannot withstand intensity of shaking due to lack of seismic renovations, which underscores the importance of implementing seismic retrofits, to protect the public, Fischer said.

Barbosa said he saw the effects of earthquake devastation first hand when he visited Mexico last year after a 7.1 magnitude earthquake. The country had a similar earthquake occur 32 years prior in 1985.

There was a school that collapsed in Mexico that was not retrofitted after the earthquake in 1985 and some kids died,” Barbosa said. “It is unfortunate but I met a mother who was a doctor there and who learned that her daughter had died in that school during the earthquake shortly after she completed a surgery.”

Barbosa said no one should even think twice about putting seismic retrofitting on places like schools and hospitals because it can save many lives in the event of an earthquake. 

Ashford said these types of earthquakes make relief and recovery efforts difficult because such a wide area will be affected.

It is predicted that much of Highway 101 would be shut down along the coast while some parts of Interstate 5 will remain open making it hard to travel, Ashford said.

“What you would expect in this earthquake is a loss of electricity, drinking water and sewage. Phone lines would probably go down and cell phone service would go down after the battery life dies,” Ashford said. “Transportation would be impacted and most of the routes to the coast would be shut down from landslides or bridge failure.”

Fischer said the historic downtown of Corvallis will be  vulnerable to damage because of the abundance of unreinforced masonry buildings.

“The way these buildings are constructed is everything is pocketed into one another,” Fischer said. “The brick masonry is built without any mechanical connection to the floor beams and there is no steel reinforcement in the planes of the wall. What is holding it together is grout and pocketed connections. As everything starts shaking back and forth the floor beams disconnect from the wall, floors collapse and unreinforced brick walls collapse.”

According to Fischer, Oregon has a seismic rehabilitation grant program that allows for schools and emergency buildings to apply for grants upwards of two million dollars for retrofitting, which some Corvallis public schools have made use of.

There are two waves that come when an earthquake hits. First you will feel a jolt that is the primary wave then the shaking comes in a separate wave causing the physical damage, Ashford said.

“If you feel the jolt, depending on how far away the earthquake is you have a few seconds of warning. If it hits over at the coast you will have maybe a 10 second warning before the shaking,” Ashford said. “If you are on the coast you will have 15-20 minutes after the jolt before a tsunami will hit. It takes time for the wave to form and come on land.”

Fischer said everyone must be personally prepared for the earthquake because the state’s emergency response management will be busy and occupied responding to medical emergencies and surveying the scope of the damage directly after the earthquake. 

“Emergency management is not going to come and help you for a minimum of 10 days, probably upward of two to three weeks, because they need to survey the damage and they are going to respond to medical calls first and the more socially vulnerable populations like the elderly.”

Many will not be prepared for this tomorrow, but there are little things that can be done over a period of time that will make the task less daunting, Fischer said.

“Every time you go to the grocery store you can buy more nonperishables or cases of water,” Fischer said. “You can buy batteries and pick up an extra flashlight. Every week these little things add up. After a year you are able to accumulate a good amount of emergency supplies.”

Ashford said it is important to communicate with family and friends and prepare as much as physically possible.

“Educate yourself, have a plan and just be prepared,” Ashford said.

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