Question

question 1 (5 points)
listen
what can cause the eruption from a shield volcano to become explosive?
a) water accumulated in the vent
b) mantle plumes
c) caldera collapse
d) subduction
question 2 (5 points)
listen
what type of material is found in the asthenosphere?
a) an incompressible fluid of molten rock
b) solid rock
c) a mixture of magma and superheated water
d) a viscoelastic fluid of molten rock

Explanation:

For Question 1: Water accumulated in the vent can cause an explosive eruption in a shield volcano. When water comes into contact with hot magma, it rapidly turns to steam and builds up pressure, leading to an explosion. Mantle plumes are related to the formation of shield - volcanoes rather than making their eruptions explosive. Caldera collapse occurs after an eruption, not as a cause of an explosive eruption. Subduction is associated with different types of volcanic activity like in subduction - zone volcanoes, not typically with explosive eruptions in shield volcanoes.
For Question 2: The asthenosphere is a layer of the Earth's mantle. It is composed of a viscoelastic fluid of molten rock. It is not an incompressible fluid (A is wrong), not solid rock (B is wrong as it is ductile), and not a mixture of magma and superheated water (C is wrong).

Answer:

Question 1: A. Water accumulated in the vent
Question 2: D. A viscoelastic fluid of molten rock