New findings on the developments of the earthquake disaster

[orogenicman]

There is evidence of cyclic bulging associated with each of the past big quakes on Cascadia. There is evidence, for example, of land that was dry and forested when each cascadia earthquake struck, but were covered with tsnami sand deposite and then become innudated for hundred of years afterwards by brackish water after each quake, thus implying slow uplift between quakes, rapid subsidence during and after each quake. I don't know what is the degree of bulging now, but I do know there are formerly forested land that submerged with the 1700 quake that still remain submerged as coastal lagoons, with dead aspens sticking up through the water surface. So maybe the bulging has not reached its full extent and a quake is not imminent.

That sounds like what I have read. Understand that when oceanic crust gets subducted, what happens is that where the fault becomes locked on both sides, bulging can occur on the hanging wall side (in this instance, on the North American plate side). When the rupture occurs, the oceanic crust slides down into the Earth, releasing the built up stress, and so the bulge will subside. In the case of the Cascadia subduction zone, what I have read is that they have noted long-term slow slipping along the fault, an effect called a slow earthquake. This often happens when the rock on both sides of the fault consist of serpentine, which is very slippery and allows the rocks to slide slowly past one another. This might explain why there appears to be no apparent bulging going on today. And if that is the case, it could mean that the stress is slowly being released, and so not building up to a megaquake. But I don't think that this is in any way a certain thing.