Using Flubber to Study Glaciers

A Hands-on Experience

Making a glacier from Flubber

Sources: Left: http://polenet.org/?page_id=137Right: http://www.geology.um.maine.edu/user/Leigh_Stearns/teaching/flubber.html

GPS

Diagram of what happens

This is land

Figures courtesy: John Wahr (U of Colorado)

Add load, perhaps a glacier

GPS

What’s going to happen to the GPS? Will it go up/down, closer/further from

the glacier?

Add load GPS

GPS moves downward and towards the load

The land flexes downward; the GPS moves downward and closer to the

glacier

GPS

Now the glacier melts. How will the GPS move?

remove load GPS

GPS receiver moves upward and away from the load

As the glacier melts, the GPS moves…

Measuring the Crust and Mantle Move

SourcesIce• Ice-age melting• Present-day

melting

Water • Ocean tides• Wind-driven surges• Reservoir depletion

Air• Water Vapor• Weather systems

as noise and signal (information)

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Measuring the Land Rebound (or Sink)

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Glacial Isostatic Adjustment

Vertical changes measured by GPS

Sel

la, G

. F., 

S. S

tein

, T. H

. Dix

on, M

. Cra

ymer

, T. S

. Jam

es, S

. Maz

zotti

, an

d R

. K. D

okka

 (20

07),

 Obs

erva

tion

of g

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“sta

ble”

N

orth

Am

eric

a w

ith G

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, Geo

phys

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4, L

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2006

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2708

1.

Green line shows 0 mmyr vertical “hinge line” separating uplift from subsidence.(left) Vertical GPS site motions (right) Horizontal motion Red vectors represent sites primarily affected by GIA. Purple vectors represent sites that include effects of tectonics.

Horizontal motions measure by GPS

GPS horizontal velocities with motion of rigid North America removed. Interpolated velocity field based on these data derived using GMT

Sel

la, G

. F., 

S. S

tein

, T. H

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on, M

. Cra

ymer

, T. S

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es, S

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zotti

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d R

. K. D

okka

 (20

07),

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erva

tion

of g

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al is

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2006

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Horizontal GPS Motions

Fig. 5. Assessment of core station selection. Velocities of core stations (with yellow circles) are shown together with other frame stations, indicating the effects of plate boundary deformation in the west, and post-glacial rebound in the northeast. To compar... G

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Weighing the ice sheets

13

Continuous GPS in the Arctic

Short-term elastic deformation of the ice load, providing a measure of large-scale melting, and hence contribution to sea-level rise

Open circles are the POLENET network

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