Vrtra : an earth bund?

[s. kalyanaraman]

     Some time back, Dr. J. B. Bapat of Monash University had posted an 
     inquiry on this subject.
     
     He had noted that it was claimed in a paper in a conference that, 
     vedic Vrtra was an earthen bund formed by tectonic shifting in the 
     Indus region. 
     
     Were there any responses to this inquiry? 
     
     If some references to soma are allegorical, could the term 'vrtra' 
     also be interpreted similarly? Dr. S. Kalyanaraman