Reading this, please keep in mind I'm not a professor of geology or chemistry, okay I'm guessing that a speed up (I think it's not really a jump start as the tectonical movement already happens) would cause all of the upper: earthquakes, volcanoes, breaking of tectonical plates - or actually: it would speed all of this up. Why: the process of heating and melting the crust material that is then moved within the mantle and resurfaces ad the mid-oceanic ridges or oter volcanoes is a continouus circle. It's not a like a factory where a shipment begins at one end and te products is at the other - the material doesn't run out like a shipment would. As long as the direction of the movement wouldn't change, the breaking would continue on these fractional lines, volcanoes would build up as they always would and earthquakes would work exactly te same. Merely the time would be sped up in general. So if anything "new" would come up it would merely surface some place it would have surfaced either was because conditions would have met anyway. Keep in mind: if you were to jump start the tectonical movement the only way (even considering magic) would be a manipulation of the chemical and physical make up of the earth, if you get what I mean. The kind of tectonic activity, the time it takes is dependant upon the physical forces at work and the chemical reactions within the earth. Just speeding up time measurement wouldn't do anything. We'd just count more days til something happened. Speeding up time in general would probably do as I've described above: speeding up the entire process, but also speeding up life of everything on earth - so little would actually happen, I guess.
Probably very little would happen, the plates move because they are being pushed around by tremendous forces. Moving them faster would require you simply increase the amount of energy you put on said plate. Between plates, the increased energy would result in increased volcanic and earthquake activity. These are a result of energy being stored up in the plates, you are adding energy so they'd be released more often and be more powerful. The plates of the earth is a very tiny percentage of the planet, they're basically eggshell-thin layers of solid rock floating around on an ocean. It's the movement of the ocean underneath that actually causes movement. Chemical reactions have nothing to do with this, SpokenSilence is mistaken, all of the heat energy that keeps the magma oceans circulating is left over kinetic energy from our planet forming and nuclear decay from heavy elements. Keep in mind that not all plates move at the same speed.
I firmly disagree with the spokensilence statement. Sorry. The way to speed up plate tectonics is to speed up the flow of the mantle below the crust (I have no idea how you plan to do that other than be heating up the core of the Earth, which, again I have no idea). Keep in mind a few things. The mantle is not magma. It's so pressurized that it doesn't have the same properties. Think of it as solid rock flowing. Extreme density creates the heat. The plates move on this metaphorical ocean, but they aren't exactly floating. More like attached to a slow conveyer belt that rams them into something (convergent), pulls them away (divergent), or slides them against (transform). Forces to create this heat would likely need to be on the order of creating an even heavier gravity to pressurize the rock further in order to heat it more. If the plates are moving faster, likelyeverything will happen faster as mentioned, but also stress levels on the plates would be exponentially more. The plates wouldn't have the same recovery times, and likely fracture. Another aspect you may not have thought of is the Earth's magnetism. The mantle controls this my heating and cooling rotations from the core to crust. Magnetic fields would be greater and further reaching. That could have an odd plethora of effects, especially on any kind of electronic technology or signals. Just some thoughts.
With magic in place, I wonder what the increase of magical energy has in terms of consequences? Think of it like radiation, which can have severe consequences on lifeforms and nature. The same could apply to the magical energy of your world. Meaning, magical anomalies as additional consequences for attempting to jump start the planet. Like floating rocks posing a potential hazard by falling on innocent bystanders, or plants growing wildly and destroying everything in their path. That way the reader will know, "Oh- its magical..." which basically gives you the freedom, to go completely nuts with the consequences without the reader questioning them too much. Basically, why does it happen? - Because magic...
I think the OP is looking to understand the geological effects, rather than how it could happen. After all, it's a magical world. For one, volcanic activity would increase, particularly in places like the Pacific Ring of Fire. Earthquakes at stress points such as the East Africa Rift Valley and the San Andreas Fault would increase - if you consider that a major earthquake hits the Japanese Kanto area approximately once every century, if you increase that rate to once every 50 years, living in those areas could become impractical. Undersea faults would become more active, creating tidal waves and tsunamis more regularly. Two major tsunamis have hit the Asia-Pacific region in the past 15 years. Doubling that rate would be disastrous. In mountain ranges like the Himalayas, rockfalls and avalanches would also become more common.
In case you don't know, all life is subject to evolution. Meaning, not only animals (and with that humans too) would be subjected to the evolutionary speed-up, but also plants.
Put it this way - the East Africa Rift Valley, one of the most visible signs of tectonic plates splitting, will take another 10 million years to rupture at the current rate of movement. Thus, if you wanted to speed that up to within a lifetime, you'd have to speed up plate movement by a factor of 200,000.
I've already told you some of the effects. The plates can't move without the mantle moving faster. That's like dragging a tissue paper over a grinder. It would tear the crust apart. You need to speed up the mantle, whichbrings a whole host of other issues. And @Naomasa298, no the effects would not double, they would be exponential. Damages would be worse because the plate movement isn't allowed its settling time. They would become brittle at their boundaries and fracture. The slow push of these plates creates the mountain ranges, but fast movement would be like ice shelves hitting shoreline, they split and fold, creating boundaries of rubble. Opposite would actually happen with divergent. Too much surface area spreading to fast likely cause the openings to first have wide oozing shield volcanoes, but they would cool too fast and solidify. Transform faults would be in constant disintegration from slippage. Those places like california would be unlivable. What you're really looking at is massive destabilization. The co2 spike from volcanic activity would likely shroud the Earth and quickly kill its life in regards to geo time. Also, as said geomagnetism is a problem in that a good portion if Earth's animals use this sense for guidance. Who knows what effect a greatly increased geomagnetic flux of the planet would cause.
I wonder if it will have an impact on the atmosphere. It won't be much I'm sure but I'd expect to see some impact. Did you see the news that magnetic north is moving at 34 mph lately? The DOD had to request an expedited update to their navigation systems due to the move.
Probably an expansion of the ionosphere. I used to live at magnetic North. I imagine the mining had something to do with it. Iron mining ramped up lately.
They say it's always moving somewhat due to small density fluctuations in the Earth's core but over the past few years it has really sped up, thus the need for emergency system updates for DOD. Just something I found interesting.
Increased volcanic activity would have a significant effect on the atmosphere. Outgassing would release greenhouse gases into the air and lower the albedo of the Earth, causing more sunlight to be absorbed. See Venus for reference.
