A real good technical paper on diatremes; here is the link again,

http://bioge.ubbcluj.ro/~bonac/pdf/2002/tamas.pdf

They are tough to find because of deflation of the breccia pipe as the explosive event quiets down and subsidence of the surrounding area, they become topographic lows and get buried.  One point that is made in the literature, once a potential diatreme is located, they are very easy to diagnose by recognizing several common features of diatremes; like a maar lake and oval surface expression, presence of mineralization and intrusive or volcanic rocks...  any of this sound or look familiar?   This is really a case of "if it walks like a duck, quacks like a duck then..."  The best thing about diatremes and Camino Rojo is that they usually occur in clusters, a good reason to expect more discoveries.

Just my opinion, could be all wrong, but my best guess.   Not investment advice.