It would appear the Earthlord's cannot catch someone with SOS as they are too slow, this shouldn't be the case. Each level of high level Earth pet increases its move speed. I believe its speed 3,4,5 respectively.
You can find ancient writings on this, one such text was reposted on the Uthgard forum: Earth Elementals come at 1, 7, 12, 20, 32, 40, & 48. They all last 60 secs, have the strongest melee attack, and are blue con from 32 on. Each spell past 32 increases damage and greatly increases speed (Abbadon did a test chasing down a Minstrel and the 48 caught him at Speed 5, but not when he was at Speed 5 and Sprinting). They are defensively weak, though. If you have a naked pet that can run speed 5, carries a polearm, and has a Con Debuff, that would be an Earth Elemental.
source: https://www.uthgard.net/forum/viewtopic.php?f=111&t=38986
You can also see this briefly mentioned in the patch notes for 1.65: Theurgist
Added new earth summon spells in the Theurgist Abrasion list at levels 40 and 48.
Added new ice summon spells in the Theurgist Refrigeration list at levels 32, 40, and 48.
Reduced the hitpoints on earth elementals, but increased the duration of their summon from 30 to 60 seconds. Their offensive bonus and run speed increases with higher spec.
You can also see it referenced here : https://daocpedia.com/index.php?title=Theurg
You can find ancient writings on this, one such text was reposted on the Uthgard forum: Earth Elementals come at 1, 7, 12, 20, 32, 40, & 48. They all last 60 secs, have the strongest melee attack, and are blue con from 32 on. Each spell past 32 increases damage and greatly increases speed (Abbadon did a test chasing down a Minstrel and the 48 caught him at Speed 5, but not when he was at Speed 5 and Sprinting). They are defensively weak, though. If you have a naked pet that can run speed 5, carries a polearm, and has a Con Debuff, that would be an Earth Elemental.
source: https://www.uthgard.net/forum/viewtopic.php?f=111&t=38986
You can also see this briefly mentioned in the patch notes for 1.65: Theurgist
Added new earth summon spells in the Theurgist Abrasion list at levels 40 and 48.
Added new ice summon spells in the Theurgist Refrigeration list at levels 32, 40, and 48.
Reduced the hitpoints on earth elementals, but increased the duration of their summon from 30 to 60 seconds. Their offensive bonus and run speed increases with higher spec.
You can also see it referenced here : https://daocpedia.com/index.php?title=Theurg