Late afternoon, going into sunset , May 18, 2013 (100UTC May 19, 2013) … several plumes appeared in central west Mexico — quickly followed by large prominent columns (steam or smoke?) produced near the Texas border.

Location .. somewhere very close to:

29°12’52.46″N , 102° 1’15.06″W

If you look at the area on Google earth, you will quickly come to see

1) It is a desert

2) There are several very old (dormant) volcanoes at this location

from:   http://sincedutch.wordpress.com/