I believe that the majority of Elsevier journals use a standard dual column document class.
However, some journals that are owned by Elsevier use an alternative single column format (e.g. J. Comput. Phys.; J. Sound and Vib.).
What is the reason for using a different format for these journals? My first guess would be that since historically those journals were single column format they may keep this format, but why then did Elsivier move them to their own single column format (narrow margins and smaller font) instead of moving to dual column (easier to read) or just keeping the same words-per-line that the journals had beforehand?
Personally I find it more difficult to read the current single column format (post 2002)