This outbreak of sinkholes, mysterious as it may seem, is easily explained if we postulate a secret underground civilization, undetected lo these many years, working toward the surface and about to break forth.

Perhaps it's the technologically advanced Vril-ya. Or maybe it's malicious deros. Or could it be the denizens of Agartha, populating the Hollow Earth? All we can truly know is that the day of their advent cannot be too far off!

I for one welcome our subterranean underlords...