Tuesday, January 14, 2014

More radar: Bisgletscher

Last week we took the radar to another spectacular spot: We flew up to Domhuette in Mattertal to look at Bisgletscher across the valley. Bisgletscher has been moving pretty rapidly and there is concern that pieces could fall off and threaten the road and railway near Randa.

Below is a view from Domhuette. The mountain across is Weisshorn, at 4,506 m. This picture shows 3000 m of vertical relief. The other side goes up by the same amount, making this the deepest valley in Europe. Just below the summit of Weisshorn is a hanging glacier that has lost major parts in the past. Further down is Bisgletscher, which we tried to survey this time. In the lower right corner are the leftovers from a massive rockfall that occurred in the early 90s.

Below is a radar interferogram calculated from two images taken 15 minutes apart. The colorscale extrapolates the motion that occurred in those 15 minutes (about 10 mm) to meters/day. So the glacier (circled in red) is moving at nearly 1 m/d towards us observers. The non-zero motion that shows up for bedrock is atmospheric noise that I have not yet removed.

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