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Wednesday

4 important questions on Wednesday

Sprengisandur: middle of iceland, noe of regions with highest uplift rates

See the crust splitting. Crack is very recent, approx 20 m deep.

Illustrates how spreading of 1 mm/yr on average, but locally this could occur in big jumps (easily up to half a meter).

Crack creates new drainage basin. But tectonic forces are also influenced by mass at landsurface, which is for instance influenced by storage of ice. Glaciers are melting fast, reducing mass at land surface, which influences tectonics and potentially influences also volcanism.

Seasonal snow: snow that remains over summer. This could make a significant runoff contribution during summer.

Amount of snow increases with elevation (as temp decreases with elevation).

Snow patches/accumulation on places in landscape where you would not expect them: along valley ridges, on lee side where wind is strongest/radiation lowest.
Idaho example.

Average snowfall order of 0.5 m max, as total precip here is not that much. Couple of yrs of snow accumulation, starts to look like the beginning of a glacier.

Snow patch melt: create a source of water input for streams even though there is no precip. Important for stream flow generation! Snow stays much longer than on a uniform slope.

Morpho: show volcanoes (active have orange circles; small inner circles with lines in middle are calderas). At this point, active volcano with caldera. We are inside a volcano.

Caldera: magma chamber relatively close to surface, that empties when you have extrusive vulcanism, you can get a gap in the landscape/subsurface, the relatively thin roof is collapsing inside the whole in landscape, that is called a caldera.

Forests also influence streamflow dynamics

In many countries are reforesting areas to create buffer against flooding. Could be a good motivation for Icelanderes as well.

Forests on flood peak evidence is limited scientifically. Partly because good data lacks or maybe these forests are too small to buffer large peak flows during floods.
Maybe some local influence, but not on regional scale.

The question on the page originate from the summary of the following study material:

Excursion Iceland

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