Is there a shortage of muses?

So, as you know I read both Michael Connelly & John Connolly. They obviously aren't related. However, having now read a good percentage of both their works, I am disturbed by some (perhaps) coincidences.. For example - both Bosch & Parker have or had a relationship with a woman named Rachel (spelling may vary) who is a criminal profiler. Both Basch & Parker are or were cops & they both are or were private investigators. Add to that they tend to follow their own path rather then tow the line & I am questioning whether in the writing world, there may be a shortage of muses? Or perhaps muses who are providing the same ideas to different authors.

Further case in point, I read a book by Patrick Robinson called Scimitar SL-2. The premise of this book is that terrorists are plotting to launch missiles into the side La Cumbra Veja (sorry if spelling is wrong) a massive volcano in the Canary islands in order to create a massive tidal wave which will devastate the east coast of the USA.  It's a well known fact that the western face of this volcano is slipping & that when it finally collapses into the sea, the devastation on the eastern seaboard of the USA will be tremendous, do to the shear volume of ocean that will be displaced.


Source: Amazon.com



 Fast forward to my amazon browsing today, where I was shocked to discover a book by Stephen Coonts et al(2011), called "Deep Black: Death Wave" which by the synopsis looks pretty darn similar to the book by Patrick Robinson published in 2005.

Source: Amazon.com

Now I am a pretty skeptical person and the size of the correlation between these two books actually scares me. Because it's not like they came out within months of each other, there is a good 6 years between them.. so is someone recycling ideas or is some muse having a great laugh at the expense of people?
  Being a bit of a disaster buff, I know there will always be similarities between certain types of books, but I do have to wonder if someone is having a laugh at consumers. Because seriously, it seems that way to me. It's a sad day when writers start coughing up books which have so many inherent similarities that you start to wonder where exactly they do get their ideas.