2 - Rheology of magma

Question 1

what is rheology

Answer 1

how a liquid behaves under stress

Question 2

what is viscosity

Answer 2

a fluids resistance to flow - how runny a liquid is - more viscous = less runny = more explosive

Question 3

what are some factors that effect viscosity

Answer 3

Silica content, magma temperature and gas content

Question 4

how much silica does rhyolite contain

Answer 4

> 68%

Question 5

how much silica does dacite contain

Answer 5

63-68%

Question 6

how much silica does andesite contain

Answer 6

53-63%

Question 7

how does temperature affect viscosity

Answer 7

viscosity increases significantly when cooled (due to crystallisation)

Question 8

how do crystals affect viscosity

Answer 8

crystals increase viscosity

Question 9

at what crystal percentage is magma uneruptable

Answer 9

60%

Question 10

how do bubbles effect viscosity

Answer 10

increase or decrease based on flow and shape of bubbles

Question 11

what shape bubbles increase viscosity

Answer 11

spherical bubbles

Question 12

what shape bubbles decrease viscosity

Answer 12

elongated bubbles