Maybe you learned about it in high school, saw it in newspapers or maybe you have a subscription to The New Yorker. Or maybe all this earthquake talk is new to you.
Seismologists predict that the Northwest has a 37 percent chance of experiencing a Cascadia Subduction Zone earthquake happening in the next 50 years. It will be so disruptive, it will change the Pacific Northwest forever.
But How Prepared Will Residents Be?
That depends on what we all do now, before it strikes. You can prepare for it. And the first step to preparedness is knowledge. So, let’s meet “The Really Big One.”
How We Know The Megaquake Is Coming
Over its 10,000-year rupture history, earthquakes around magnitude 9.0 occurred along the length of the Cascadia Subduction Zone 19 times — about every 526 years. The southern section of the CSZ has seen 19 additional quakes of 8.0 or higher.
A magnitude 9.0 earthquake off the Northwest coast could hit at any time. How can we prepare for this impending and unpredictable disaster?
Along this southern section, the average recurrence is every 234 years. With the last major event placed at 315 years ago, we’re due.
Umm, What’s A Subduction Zone Earthquake Again?
A subduction zone is a large area where two plates of the Earth’s crust meet and one is forced under the other. The plates sliding past each other cause extreme amounts of force to build up as friction restricts the movement. When the amount of force exceeds the friction holding it back, the plates slide past each other, causing the ground to rumble.
This causes the largest type of earthquake on the planet.
How Powerful Is A 9.0 Earthquake?
A magnitude 9.0 earthquake is measured in moment magnitude, which is the measurement of the exponential increase of energy as the magnitude increases.
Here’s another way to look at it: If a magnitude 3.9 earthquake equals 1 grain of sand, then a magnitude 9.0 would equal 100 million grains, or about 572 pounds.
Energy Released By Different Magnitude Earthquakes
A magnitude 9.0 earthquake doesn’t release nine times as much energy as a magnitude 1.0. Moment magnitude — the scale seismologists use to measure earthquakes — measures the exponential increase of energy as the magnitude increases. A magnitude 9.0 earthquake actually releases about 11,099,511,600,000 times as much energy as a magnitude 1.0. This graphic aims to show the dramatic increase from a magnitude 3.0 earthquake, the type of earthquake people barely feel, to a magnitude 9.0, the magnitude of the earthquake that hit Japan in 2011.
Be Prepared
A mobile kit should have enough supplies to last at least three days, which should give enough time to find a more permanent shelter. People living in remote areas may need more supplies.
• Three days of food that doesn’t need to be refrigerated or cooked for each family member • Three gallons of water per family member • Battery or hand-crank powered radio • Flashlight • Extra batteries • First aid kit • Supply of medications • Multipurpose tool • Copies of personal documents, such as insurance and identification • Extra cash in small denominations • Personal hygiene items • Whistle to signal for help • Local maps • Duct-tape • Manual can opener • Household liquid bleach for water purification, plus eye dropper for measuring • Waterproof matches • Baby supplies if needed • Pet supplies if needed • Rain gear and warm clothes • Insect repellent and sunscreen • Extra clothing • Emergency blankets
The American Red Cross also recommends that you always keep your vehicle filled with three-quarters of a tank of fuel in case you need to leave in an emergency.
About Unprepared: Will We Be Ready For The Megaquake?
Geological evidence shows that devastating 8.0 or 9.0 earthquakes, and accompanying tsunamis, have been striking Oregon every 300-400 years. OPB News and Oregon Field Guide have launched a year-long initiative to inform people about the dangers of a megaquake, and to examine ways that our region can be better prepared. You’ll find information here about earthquake science, lessons we can learn from Japan, personal preparedness and more. Look for OPB’s special Oregon Field Guide documentary coming Oct. 1, 2015.
