Geokinesis is the last set of psychic powers from Angels of Death. It is themed around manipulating the earth and features a plethora of earthquakes and volcanic eruptions. As such, it's especially appropriate for Salamanders Librarians, but any Space Marines can use it.
Chasm is the primaris power, and is a WC2 power without a classification (it sounds like a Malediction but isn't labeled as such). It targets an enemy unit within 18" of the caster, and every model in the unit must take a dangerous terrain test with no armor saves allowed. This will likely cause a wound to 1/6 of the models in the unit, barring invulnerable saves. Against very expensive models or very large units, it might be worth it but it seems like a steep price for little damage in most circumstances. Casting it on a Green Tide would be hilarious.
Earth Blood is a WC1 Blessing that restores D3 wounds to a friendly non-vehicle character model within 18" and grants It Will Not Die. Depending on your army build, this power ranges from useless to amazing. If the only multi-wound character in your army is your 2 wound Librarian, it won't do much for you. If you have an Eternal Warrior 2+/3++ Chapter Master in your army, Earth Blood will make him almost unkillable. Since Geokinesis is so suitable for Salamanders, who have the capacity to field multiple very tough combat characters, this is a match ordained by the Emperor.
Scorched Earth is a WC1 Malediction that targets a point on the battlefield within 24" of the psyker. Each unit within 6" of the point takes a S5 AP4 hit that Ignores Cover, and all terrain within this area counts as dangerous terrain. This won't do much damage unless a very large unit with poor armor saves passes through the area. As such, it'll be great against Orks and Tyranids, but not much else.
Landquake is a WC1 Malediction that forces every enemy unit within 18" of the psyker to move through difficult terrain. Targeted units also can't Run, Turbo-Boost, or move Flat Out. While it requires your psyker to get into the midst of the enemy, Landquake allows you to greatly hinder the mobility of a huge chunk of the enemy army (a 36" diameter bubble). Against any army but a static gunline, this power is really great as it can throw a huge wrench in the enemy plans.
Phase Form is a WC1 Blessing that targets a unit within 24". The target gains Move through Cover, all of its weapons gain Ignores Cover. In addition, the unit doesn't need line of sight to shoot; it can target any enemy in range. This power is amazing on static shooting units like Devastators. Suddenly, their lack of mobility is not a hindrance; they can absolutely hammer any enemy within their considerable range.
Warp Quake is a WC1 Witchfire that targets a building or ruin within 24". If you target a building, it takes a glancing hit on a 1-3 and a penetrating hit on a 4-6. Given that most buildings are AV14 and some are AV15, such reliable damage is great if you ever see one on the table. If you targeted a ruin, you roll a die for each unit occupying it. On a 4+, that unit takes D6 S6 AP- hits. I often see a large ruin packed with shooty units (I often do it myself with two Devastator squads and my Thunderfires), and this is a good way to punish those units. Unfortunately, it doesn't affect all units automatically and it doesn't ignore cover, so some units will just shrug this off (for example, Scouts with camo cloaks in a Techmarine fortified ruin will have a 2+ cover save, so this won't do much to them). Even so, Warp Quake is a good tool to have if this situation comes up.
Shifting Worldscape is the other power that set the internet on fire when it was released, for much the same reason as Electrodisplacement: it allows first turn assaults. Shifting Worldscape is a WC3 power with a 24" range. It allows you to move a piece of terrain to anywhere within 24" of its starting position as long as it is entirely 1" away from models and other terrain. Units that are completely on the piece of terrain move with it, while units partially on it are disembarked and take Dangerous Terrain tests.
If you're trying to transport an assault unit, Shifting Worldscape is extremely dependent on the table set up. If the terrain is at all dense (as it should be for most 40K games), there won't be many places to legally drop a large piece of terrain. Your opponent can limit these even more with their model placement. If you do pull off a first turn assault using a terrain taxi, my hat is off to you, but I don't think it's the easy win that many people initially thought it would be.
However, I do think Shifting Worldscape is a strong power. The ability to reshape the table can be much more useful than just repositioning a unit. You could drop line of sight blocking terrain in front of your opponent's powerful shooting units. You could move difficult or impassable terrain in front of their assault troops or force their vehicles to constantly take difficult terrain tests. Move cover away from enemy objectives, forcing their units to stand in the open. Shifting Worldscape is a tremendously flexible power, so don't focus in on moving your units with it.
Geokinesis contains some extremely strong powers in among very situational abilities. In my mind, you'll generally be looking for Landquake, Phase Form, and Shifting Worldscape as these will help almost any style Space Marine army against most opponents. Earth Blood also stands out if you are taking an Eternal Warrior Chapter Master. The other powers are limited against many opponents, but four very good powers out of seven means that Geokinesis is definitely worth considering.
Also, if you play Salamanders, how do you resist? I guess you could play Pyromancy...