WTG - Ch 4 - Bouncing Back Flashcards
(3 cards)
What is isostasy?
This is the way the Earths crust responds to the addition or removal of mass from the surface of the earth. When mass is added the crust is pushed down. When mass is removed the crust rebounds back up.
What is glacial isostatic adjustment?
This is the way the earth’s crust responds to the weight of a glacier.
What is the link between ice ages, the weight of ice and liquid water and earthquakes? give an example
The added weight of an ice sheet on the earths crust will reduce earthquake activity. Ice will contain the rock and the stress in it such that the rock can’t move. The effects of liquid water on earthquakes. The presence of a large body of water on the crust such as a lake also represents a significant weight. However, earthquake activity is not inhibited, it may even increase beneath a lake. The weight of all this water forces it into the underlying bedrock where it can cause rocks to move and earthquakes to happen because of increased water pressure in the pores. A possible example of isostatic rebound and earthquakes is New Madrid earthquakes of 1811 and 1812. During the last ice age the Laurention Ice Sheet covering most of North America pushed the crust beneath it down. Next to it the crust rose upward in the form of a peripheral bulge. When the glacier melted the crust rebounded and the peripheral bulge collapsed. Perhaps the collapse of the bulge contributed to the New Madrid Earthquakes.
