Crack in the World

[stickmaker]

Just a bit of casual curiosity/thought experiment. Glaciologists sometimes place a line of poles across a glacier and photograph (and even plot the positions using GPS) through time, to show how the center of the flow moves more quickly than the edges.

Is there a place on Earth where a subduction zone could have poles driven into the plunging bedrock to directly and visibly measure the movement?

We would need a location with little overlying debris (hence eliminating the Mariana Trench, where there's a thick layer of sludge). This must also be a place where the subduction is proceeding quickly enough to produce a visible result in a few years (a typical rate is measured in centimeters per year, so that shouldn't be a problem) and at least somewhat steadily on this time scale.

I doubt there would be a scientific justification for this, but it would be cool to watch in time-lapse.

Comments

[solarbird]

Ours is under the ocean, unfortunately.

[kengr]

TTBOMK all of them are underwater. And you get the sludge because it's getting scraped off the seafloor that's being subducted.

[maellenkleth]

Onshore subduction? Easy: Beaufort Range Thrust (an overthrust fault), an upper splay off the Cascadia Thrust System, nicely-exposed in a road-cut on highway BC-4, east-northeast of Alberni, Cascadia.

Lovely bright red, sheared, thermally-altered rocks, with concrete-based subduction-survey monuments on either side.

The eastern, overthrust, side is rising at ca. 11 millimetres a year; given it being ca. 300 years since the last big rupture (and 58 years since the last significant aftershock), the strain is definitely accumulating.

Map sheet 92 F/7 shows it.