This plugin lets you change the hard coded base URL for the the pages displaying the authors posts. Change from {site url}/author/{user slug} to {site url}/{your base}/{user slug}.
Why woud you want to use it? While author might be a good default for blog style sites, it doesn’t work well in niche sites in which you might prefer “contributor”, “teacher”, “specialist”, etc. Another big problem with the “author” base is that it is impossible to localize.
Settings
The author base can be changed at the “Settings” >> “Prtmalinks” admin page, at the “Optional” section. Like the category and tag base settings, an empty value indicates that the default balue of “author” should be used.
Compatibility
WordPress versions 3.9 and above, for both standalone and multisite/network