Predicting earthquakes is still a long way off but the discovery of slow slip tremors many miles below the active fault lines where seismic activity is felt on the surface has opened a window of possibility. Last August, another series of the regularly occurring tremors were recorded and because these slow slip events help load an already shaky fault line, an earthquake is more likely to occur during these events.
University of Washington seismologists have begun recording a slow-moving and unfelt seismic event under the Olympic Peninsula, and it promises to be the best-documented such event in the eight years since the regularly occurring phenomena were first discovered.
“It appears to be right on time,” Steve Malone, a UW Earth and space sciences professor, said of the most recent of what are termed episodic tremor-and-slip, or slow-slip, events. “The first signals were mostly fairly weak, but they were easily detected.”
The first ground motion associated with the event was recorded very early Sunday morning in an area north of Olympia and west of Tacoma. By Monday afternoon the signals were substantially stronger. If the event behaves like past occurrences, the source of the rumbling will move north through the Olympic Peninsula during the next week before crossing the Strait of Juan de Fuca to Canada’s Vancouver Island.
Such slow-slip events have been documented on the Olympic Peninsula at an average frequency of every 14½ to 15 months since 2002 (an event last year actually started three months earlier than expected). They typically last several weeks and can release as much energy as a magnitude 6 earthquake.
The Pacific Northwest is located along a subduction zone where the oceanic plate slides beneath the continental plate. Subduction zones create megathrust earthquakes registering a magnitude 9 and are frequently followed by massive tsunamis like that in the Indian Ocean in 2004. According to scientists at Oregon State University, the probability of a megathrust quake in the Pacific Northwest is one in three.
The NOVA program indicates a strong possibility of a major earthquake hitting the Pacific Northwest within the next fifty years. Coos Bay, Oregon is located along this earthquake fault and is a proposed site for an LNG import terminal. Siting a billion dollar terminal in Coos Bay may not be a prudent investment.
Watch the full episode. See more NOVA.
Mr. Dunn: Interesting comments. Ever experienced an earthquake? Magnitude 6 and 7 Northridge and Loma Prieta here. The earthquake expected here will be 1,000 times worse. Many local structures – too many currently erect because the termites are holding hands – will be leveled here. Water mains will break and it will be impossible to put out fires. Gas pipelines will rupture. Roads will be damaged and it may be impossible to provide emergency services. We are going to be isolated for a long time! State and federal aid will be spread thin from California to British Columbia. There are only seven ambulances in this area and there will be thousands requiring transport to the hospital that may be leveled. The electrical generator that will be keeping the “boiling” LNG in storage tanks liquified may be damaged. “Google” Kobe Japan earthquake and find what happened to similar natural gas facilities that were built on similar soils. A tsunami will not be like the Mavericks style wave pictured above. One of the safer places to be during the next Cascadia Subduction event is aboard a fishing vessel and a few miles out to sea. You can easily find information about the many who survived the December 2004 tsunami. And, re gas stations, you are probably at similar risk from the idiot filling his tank next to you while smoking not realizing the auto ignition point of gasoline is less than the temperature of the lit cigarette that he throws to the ground. My 50 year old home, former offices of the Commandant of the US Navy in Coos Bay, and the LNG facility wont be standing after the next magnitude 9 or 10 earthquake. If I could figure out where I would be safe from natural disaters on this planet, we would relocate – soon. Ask any geologist friend would they rather be living near a nuke facility or a LNG facility at the time of the next Cascadia earthquake and you will get Nuke answers. Certainly explains why people who visit this area with potential jobs dont stay after reading state and local emergency preparedness brochures and maps of anticipated flood zones.
Actually, there are already rules restricting placement of hazardous facilities in earthquake and tsunami zones.
I meant to offer the broader question, aside from the LNG terminal; what local human activities or enterprises would not survive this type of quake? It may be that much of what we now do or build is not compatible with the quake. Examples might include tall buildings, bridges, gas stations, beach combing, and fishing to guess a few. Should we apply a rule based system to filter these initiatives? Does our permitting need revisions?
If by compatible you are asking about characteristics of subduction zones, normally a mountain range with active volcanic activity runs parallel to and a bit inland of the zone boundary. This is certainly true in the Pacific Northwest.
If you mean what type of industry might be suitable, I would say an industry without the potential to explode into a 1200 degree three mile wide fireball would be a good start.
I don’t oppose the LNG terminal. I do belive that is beyond insanity to permit eight 14 story tall, 1,000 feet long, 150 feet wide, vessels monthly with four billion cubic feet of LNG to pass within 6/10 mile of three schools with a generation of Coos Bay children and faculty (more than 1,000 unsuspecting souls). Knowledgeable “experts” ALL agree that a fireball could be at least one mile wide. We’ll be relocted before the first LNG vessel causes Charleston to close or Mr. Braddock sells Jordan Cove to a major petro chemical company and they remove the first shovel full of sand. Most of my neighbors wont be so lucky. But, no new news here. Jody McCaffree, in her web site jordancoveretort.com, a site visited by more than 1.2 million people in 53 countries during a three year period, explained the possibilities of all cooking, in depth, six years ago. And, let’s not forget liquefaction. We live on a huge sand pile. Siting a LNG terminal near the Cascasdia Sudduction zone – and a possible magnitude 10 earthquake – “may not be a prudent investment” – it certainly may be hazardous to your life if you happen to be in the area between Empire and Hauser Oregon on the day of the earthquake. Which of your local elected politicians or political appointees managing the port have expressed concern?
What activities are compatible with subduction quakes?