InSAR

These rather garish images are produced from satellite radar images of glaciers and mountains.  The color shows two things: Surface topography and surface motion. The motion in particular is visible on glaciers which flow like motor oil through their confining valleys. Probably "motor oil" is not what comes to mind when you think of rivers of ice, but the comparison is reasonably fair since ice under sufficient stress behaves like a viscous fluid. The stress is provided by gravity which is pulling the ice downhill. The way these glaciers work is that the ice piles up for (let's suppose) a few hundred years as snow falls down and sticks and eventually compresses under its own weight. After a time as the ice layer gets very thick it begins to flow downhill; the thicker it gets, the faster it flows. Also the steeper the valley the faster the flow. Ultimately a glacier reaches a state of equilibrium when it flows down the valley as fast as the clouds can pile on new ice.

Ice
The following image includes glacier ice. The left-center third of the first image is the terminal reach of Tazlina Glacier. The blue and purple region at the top center is bare ground north of the terminus. Finally the banded, scalloped regions at the left and right are mountains that constrain the glacier on both sides.

Tazlina terminus interferogram


Scale: These images are about 5 to 30 kilometers on a side. The pixels are typically about 30 x 30 meters.

Place: These are three glaciers located in the coastal mountain ranges of Alaska.

Ice
The following image is mostly ice. It is the Tana Glacier and a small part of the Bagley Icefield. The dark pointy features folded over to the left are mountains rising up out of the ice.

Bagley and Tana interferogram


Ice
The image below is almost entirely ice except for a band of bare ground at the bottom edge. At the bottom edge are also visible some lakes and a small bit of the Pacific Ocean at the bottom-right. The ice itself is part of Malaspina Glacier. It is moving very very slowly towards the coast (at the bottom).  However you'll notice there are many color-features that look like little puddles of water.  This is not a coincidence; liquid water is responsible for the color-features, but only indirectly.

Malaspina Interferogram


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