Hi Panagiotis,
do you want to find that out because you want to duplicate it??
Anyway, it's very difficult if not impossible to tell. The only thing is that Verlinden was still old school (like me
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) and did not use acrylics but rather enamels.
As his pieces were resin (mostly, apart from his buildings of course) enamels are fine. In those days acrylics were rather the exception, not the rule!
So, the only advice I can give is take enamels and work until your result looks like his. Remember, it's only a photo, and the actual piece might look quite different (white balance, lighting, etc).
Don't worry too much about the "actual" colour. There is no "Pacific" colour. With different geological formations and "materials", you also have very different colours, from Iwo Jima "black" volcano ash to Guadalcanal reddish brown.
Just have fun, and remember, with enamels the basic colour doesn't matter so much. You can drybrush it countless times and use washes until you are satisfied!
Cheers
Romain