Why are shield volcanoes so broad and gently sloped?

Basaltic magma is relatively hot and fluid, so it does not pile up steeply near the vent. Instead, it spreads outward in long flows, creating a volcano with low slopes that resemble a warrior’s shield laid on the ground. Shield volcanoes commonly form over hotspots or in some rift settings, and many eruptions are effusive rather than violently explosive. Mauna Loa and Mauna Kea in Hawaii are famous shield volcanoes, with Mauna Loa among the largest volcanoes on Earth by volume. Their shape reflects repeated lava outpourings over vast spans of time.