More about the high altitude plume(s) on Mars - yes, there may have been more than one

In Response To: Mars: Strange plume seen reaching up to 150 miles above the surface by amateur astronomers in 2012 remains unexplained (MrFusion)

Today's NASA Astronomy Picture of the Day (APOD) features an animated GIF of the 2012 plume on Mars that appeared to extend as much as 150 miles above the surface (when looking at the picture remember that Mars is 4200 miles in diameter):

See also the previous post in this thread for higher-resolution images:
http://www.rumormillnews.com/cgi-bin/forum.cgi?read=10962

In the APOD posting, it is noted that similar plumes may have been seen in the past, as in this picture from 1997 (source page):

There is a discussion page about these plumes, which includes a poll as to what you think they are:

http://asterisk.apod.com/viewtopic.php?f=28&t=34478