Natural Sciences -- Cascadia subduction zone

[Gary7]

The Really Big One
It doesn't seem to be mentioned much any more these days, but back around 2015 there was a small wave of articles and video broadcast news items regarding the Cascadia subduction zone, about a 700 mile long fault off the coast of the Pacific Northwest. The upshot is that readings are indicating that the North American tectonic plate is slowly developing a bulge. It means as the Juan de Fuca oceanic plate is gradually moving, it applies friction against the NA plate. Normally the top most plate would erode its leading edge and maintain the same level.

But the NA plate in the PNW region is relatively young, and has more flexibility. It has actually gotten caught on the Juan de Fuca plate and the leading edge is being pulled backward. This is causing a bulging effect on the NA plate along the PNW segment. Because the Juan de Fuca plate abuts the Pacific plate, there's a tremendous amount of mass behind it. It will not relent. This means that there is most definitely going to be another earthquake in the PNW region--the question is when. Speculation is that there is a 33% chance of happening within the next 50 years. Beyond that, the percentage will go up. The energy release is expected to dwarf expectations of the next San Andreas quake.

I haven't seen this mentioned yet at all, but given the rise in volcanic activity at Kilauea in Hawaii, which is within the Pacific plate, I have to wonder if this is a preliminary indication of rising plate stresses. Strong enough that is causing a "leak" through a well known weak "spigot"--a gaping hole of continuous venting that has been going on for centuries. I don't expect there's a direct correlation to the Juan de Fuca plate movement, but it could be indirect.

 

[Asbo Zaprudder]

Geologic time scales >> human time scales

Geologists still can't predict a major quake or Mount St. Helens-type eruption with any degree of certainty although there will likely be forewarning of the latter type of event. Both types will happen multiple times in the future, of course, but we're dealing with an intrinsically complex, non-linear, chaotic system.

 

[GNDN18]

NASA Launching New Satellites To Measure Earth's Lumpy Gravity

Gravity Recovery and Climate Experiment (GRACE) also detects movements in the Earth's crust, which could help scientists predict earthquakes.

 

[Gary7]

Geologic time scales >> human time scales

Geologists still can't predict a major quake or Mount St. Helens-type eruption with any degree of certainty although there will likely be forewarning of the latter type of event. Both types will happen multiple times in the future, of course, but we're dealing with an intrinsically complex, non-linear, chaotic system.

True, about the scales. It's one thing to try predicting near term earthquakes or volcanic eruptions, but another for long term tectonic events. It can be even more alarming, when you think about the causes of the Permian Extinction, which happened 250 million years ago. A cascade of natural disasters culminated in an environment unsuitable for most forms of life (Siberian Trap volcanic rift causing massive cooling, gradual receding of ocean water levels from glacial progression triggering methane release, followed by massive heating). Something like that could very well happen again. The only way human beings could survive it is to retreat to the oceans, creating submerged cities capable of generating their own light so that food could continue to be grown. Otherwise, as physically equipped, human beings would easily die off. We're too vulnerable to climatic change of that degree, mainly because of food sources disappearing.

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