As I see it, this is problem with the geology of the area. These bluffs are, for the most part, unconsolidated glacial till. It's not very strong. So what happens, likely, is that runoff is concentrated in a given area, and the soil and till is saturated. Really not a great problem unti something disturbs it -- then things get interesting. I suggest that passing trains set up a harmonic vibration in the till and/or soil that literally liquifies it, and then there are these semi-solid slides that bring down rocks, trees and whatever onto the main. They cut loose because there is no adhesion that ties the soil to whatever is beneath... That might explain the extensive tree removal. It just might be that when the soil is peeled off, the exposed till will be more stable. Bottom line is that it is combination of "development" on the bluffs above the mains, and vibrations from the ever increasing number of trains combine to trigger these slides. Solutions? No easy ones, and it's gonna be very expensive. It might be nice if the old NP east side Maltby(?) sub weren't severed, but it is. and even if it wasn't, there would be a huge amount of work to make it useful for heavy use -- and the nimbys along the route would surely set up a howling and whining of biblical proportions... Other old, and long abandoned routes simply aren't practical, and were not exactly high speed and had heavy curvature. So, they have to do something about the slide areas. Tunnels? Maybe... How about moving the mains onto a bridge-viaduct just off shore? Maybe raise the mains onto a viaduct on the existing right of way so the slides simply pass underneath...
In the meantime, I'd lighten the load in this area by diverting whatever can be sent over Stampede or around the horn accordingly -- less vibration. It might also be possible to change track speed to lessen the harmonic vibrations in the area.
It would be interesting to find out if there really has been an increase in these slides in the past couple of decades. I don't think these things are simply going to go away.
Incidentally, they're having a similar problem along I90 just east of Preston.