Hey, kids, look! It's the Shield, squatting with legs akimbo while a powerful stream of distinctly not-blue liquid pours down on some poor sap, threatening to drown him in a growing river. I wonder what THAT's all about... .
I guess it's just the Pep Comics' unique brand of action detective adventure.
Usually, Pep covers focus their powerful perspective backwards toward the horizon. But this one is about the "down" of it all. Clearly, we're being given a perspective similar to the Shield's, as he watches the hapless victims doused by the powerful liquid jet he can no longer contain. Ahem.
What I find most interesting about this cover is the depiction of the bystanders, who, instead of just bystanding, are actually helping one another get out of the collapsing tunnel. A realistic scene, yes, but not the kind usually see on a cover: the hero, essential in the rescue but stalemated by the situation, while the civilian have to save themselves. It's a nice touch and demonstrated the can-do, bootstrapping attitude that pulled Americans out of the Depression and through WWII.