Final answer:
Shield volcanoes are typically associated with low-viscosity magma, which allows lava to flow easily, creating their characteristic broad and flat shapes. High viscosity magma results in more explosive eruptions and different volcanic features such as stratovolcanoes or lava domes.
Step-by-step explanation:
Shield volcanoes are associated with low-viscosity magma, not high viscosity. However, the phrase high viscosity magma is typically connected with other types of volcanoes, such as stratovolcanoes or lava domes. For example, the pancake-shaped volcanoes observed on Venus are caused by eruptions of highly viscous (sludgy) lava. In contrast, on Io, a moon of Jupiter, the volcanism is characterized by low-viscosity, hot silicate lava flows and spectacular plumes arising from the heating of frozen sulfur deposits.
The low viscosity of magma at hotspots and along linear volcanic regions enables the creation of extensive lava flows. Examples of such flows can be seen on Earth with the Kilauea Volcano in Hawaii. The broad and flat appearance of shield volcanoes is due to this type of low-viscosity lava flow spreading out in wide sheets. On the other hand, high viscosity lavas do not flow as easily and thus create different volcanic structures.