The Seismic Pressure Building Below North America’s Pacific Coast


Erinn Bloch

FAULT LINES: In Washington State, tectonic plate convergences have always been uncomfortably close to home, but a relatively recent scientific predict may show Washington residents just how destructive these convergences can be.

Isabel Smith, Staff Writer

“The Big One” is coming to the Pacific Northwest. If you have yet to hear of the Cascadia Earthquake Prediction, you may be woefully unprepared for a catastrophic earthquake that’s ready to strike Washington State at any moment in time. Members of the public have only the vaguest grasp of the Cascadia Earthquake Prediction; however, information and awareness about this prediction should be far more widespread than it currently is.

Research teams in the Pacific Northwest have been working tirelessly to amass data on a megaquake due to hit cities on the Pacific Coast from British Columbia to northern California. They have concluded that the release of pressure in the Cascadia Subduction Zone will be the cause of this massive quake. According to Columbia University, subduction zones are a particularly dangerous form of tectonic plate convergence, where one plate is thrust under another. This builds up pressure and gradually elevates the top plate. Then, when the convergence zone ruptures, the top plate drops, creating powerful seismic waves and plunging coastlines into oceans.

The Cascadia Subduction Zone is attributed to creating megaquakes every 300 to 600 years. Its last megaquake was in 1700, and as of 2000, the Pacific Northwest has hit the 300-year waiting game for this major earthquake. This discovery surfaced only recently. City Journal revealed that in the late 1980s, Brian Atwater, a geologist at the University of Washington, collaborated with Japanese seismologist Kenji Satake to expose the dangerous nature of the Cascadia Subduction Zone. They used tree-ring dating on drowned “ghost forests” in Washington, reports of an “orphan tsunami” in Japan, and ocean floor samples off the coast of America to uncover a forgotten megaquake from 1700 and other prior earthquakes.

The magnitude of the earthquake is estimated to hit at least a 9.0. At the height of seismic activity, out-of-date structures will experience complete demolition, and skyscrapers built before modern earthquake codes will bury streets in glass and rubble. Bridges, overpasses, and tunnels will suffer severe damage or collapse altogether. Soil will liquefy, underground pipes will burst, and no one will be able to stand, much less walk. To add insult to injury, this quake is estimated to prolong for a total of five minutes—ten times longer than any normal earthquake—with forceful shaking lasting two minutes.

Earthquake data is extremely difficult to predict, but it is important to be aware of how the area people live in will affect their experience of a megaquake such as this one. One of the factors that dictates the magnitude of earthquakes is the origin point of the seismic activity. According to King5 News, the M9 Project—an earthquake research team from the University of Washington—has discovered two main possibilities for this megaquake’s origin point. One is northwest of the Washington Peninsula while the other is off the southern coast of Oregon, close to the state boundary between Oregon and California.

Although it may seem counterintuitive, a closer origin point would prove greater benefit to Issaquah as there would be less time for the build-up of seismic waves. A build-up of seismic waves before it reaches King County would increase the intensity of the earthquake and play into another factor affecting Issaquah. According to The Seattle Times, Issaquah, like most of King County and the Puget Sound area, sits on a sediment-filled base called the Seattle Basin. This loose sediment intensifies shaking during earthquakes, especially for taller buildings.

Potentially more dangerous than actual earthquakes are the hazards that go along with them. Earthquakes are usually coupled with many or all of the following hazards: tsunamis, landslides, flooding, the elevating and sinking of the ground, and fires. Luckily, Issaquah does not have to worry about the worst of the hazards accompanying megaquakes. The city is too far inland to be hit with the full force of the following tsunami, though the flooding it may cause can not be overlooked. Issaquah’s most substantial hazard is landslides. Built at the base of a mountain and on the Seattle Basin, the liquefaction of soil will cause countless landslides, which will damage or collapse houses, trap many in buildings, block or destroy roads, and create major difficulties for rescue teams and the flow of emergency supplies, especially since any land assistance from the east will have to traverse through the terror that will be any Cascade Mountain pass.

Although the facts of this earthquake may be daunting enough to strike fear in the minds of many, the most alarming fear sweeping Washington should be the population’s lack of personal preparedness. At IHS, it is likely that many students know next to nothing about the Cascadia Earthquake Prediction, and fewer still are even remotely prepared for an earthquake of this magnitude. The state of Washington has been reinforcing earthquake codes and emergency procedures in order to reduce the damage and death toll of the earthquake, but Washington residents are substantially less prepared to ride out this incoming megaquake. Freshman Aubrey Cook, sophomore Abigail Stipe, junior Carah Smallwood, and senior Ellie Sytsma all admit that schools drills have been their only form of earthquake preparation and that they do not have any supplies in their homes beyond first-aid kits. Stipe said, “My household hasn’t really done anything to prepare. We don’t think about those things, and well, that’s not exactly good.”

The colossal length of time in which the earthquake will happen allows many to put off preparation. Sytsma said, “I heard about the earthquake in seventh grade from a teacher. There was an initial reaction of ‘we’re all gonna die!’ but it’s been six years, so it’s easier to distance myself from thoughts of it. You really don’t think about earthquakes happening here. In California and Asia, sure, but not Washington.”

Although outright panic would not prove productive, aversion of this potential disaster could lead to catastrophic results when it does prepare. To be caught off guard is to lose lives. When speaking about the population’s general preparedness, Sytsma said, “I think the area is somewhat but not fully prepared for an earthquake like this. There would be massive chaos and we have the basics, but we haven’t experienced an earthquake in a while and haven’t reinforced our preparedness. I think it’s ridiculous, though, that we tend to improve our preparedness after disasters have already happened. It would save lives and spare families if we prepared now.”

Educating the population on the Cascadia Earthquake Prediction is one thing, but combatting each potential hazard with swift, well-rehearsed action is another. Overall, every individual should be working to increase their personal preparedness for earthquakes and natural disasters alike, whether the Cascadia Earthquake Prediction becomes a reality during our lifetime or not.