Scientific questions regarding tectonic plates and the energy created by its activities.?

Question

My questions are: What happens to the energy that is created when the tectonic plates crash against or slip by each other? Wouldn't energy just keep building up with even greater force from each occurrence and wouldn't the energy be forced towards a specific direction? What would be the ultimate result from that ever-accumulating energy? Doesn't the visible evidence of the planet's land mass splitting apart (which could split Ethiopia and eventually perhaps other continents apart on dry land, too) an indication of that ever-accumulating and dangerously powerful energy building up, and again, to what end? Jean Rohlfing at [e-mail].

Hasn't the most castrosphic earthquakes occurred in a predictable direction from the last location of tectonic activity indicating that that energy is only increasing in power? I was taught that energy doesn't disappear-it only gets transformed.

Answer 1

The primary concern of your question deals with the possible ever accumulation of energy buildup. The best way to answer that is to see how energy is stored and dissipated by tectonic movements.

Unlimited, runaway, catastrophic energy buildup attributed to tectonic movement is difficult to take place for a number of reasons: you need tremendous generation of energy and more importantly the storage of such energy.

Unlike the Toba catastrophe where such generation and storage of energy could take place in form of heat energy in a supervolcano, the movement of plates against each other precludes this scenarios. The slow moving plates usually result in the gradual release of mechnical energy such as two plates moving toward each other to form mountains over eons. The worst scenario of tectonic movement is the build up of elastic energy at a frictioned subduction zone. Take the Indian Ocean Tsunami of 2004 for example, the two ocean plates move in opposite direction. However, at the subduction zone where two plates meet, the plate underneath the top plate "drags"the edge of the top plate due to friction. You can visualize this by extending both of your hands, right on top of left hand. As the fingers of your left hand submerges under the finger of your right hand, it "hooks" the fingernail of the right hand down and causing the right finger to curl down along with it. As the result, vast elastic energy slowly built up to the point when the top plate can no longer bent down and it just snaps suddenly up causing the great tsunami. There are two points to this incident: one is how such vast energy could be generated and stored, but more importantly is the limitation of how much energy could be stored this way, unlike heat energy build up in a magma chamber.

As a side note to this story, it also answer your question that the energy would certainly be directed at a specific direction. In this case, the direction is vertical to the fault line; it all depends on how the plates are aligned.

To sum it up, the concern is legitimate with tectonic movement accredited earthquake, not not enough to cause a worldwide catastrophic event due to the lack of mechanism to the proper "storage" of vast amount of energy, in contrast with thermal energy. Mechanical energy is gradually build up and released at the same time. Potential energy in the form of elastic property of landmass is not sufficient enough to cause a sudden catastrophic event, the worst case is a high scaled earthquake; which has taken place many times over human history. I am more concerned with the supervolcanoe at Yellowstone which is overdue for its next major eruption - that will truly be a hemisphere, if not global, event.

ADDENDAM:
The statement "Hasn't the most castrosphic earthquakes occurred in a predictable direction from the last location of tectonic activity indicating that that energy is only increasing in power?" is somewhat inaccurate. I am not an expert in seismology(my background is in physics and cs) so I can't comment the veracity of "predictable direction"; however, I can comment on the energy part.

In order to make that claim, you need to justify HOW the energy is only increasing in power and WITH RESPECT to what. Energy is not free anywhere for you to grab, nor is energy unlimited for you to store in a finite element. Seismology, boils down to the barebone is the study of what happens when two plates collide(you can't get simpler than that.) Energy only comes in a limited number of forms, and in this aspect, the only form relevant are mechanical energy(in moving the plates), thermal energy( in result of friction between plates), and elastic potential engery( in the compression and stretching of plates); that is IT. You don't store energy in neither the mechanical nor the thermal part because they are converted immediately into motion and heat respectively. The ONLY possible way for you to store energy is in the compression and stretching of a piece of landmass.

Take two pieces of Snickers Bars for example. When they are slammed head-on into each other, they get squeezed and compressed along the axis of collision as the strain inside builds up under external stress. There is no shape change, not until their shapes are deformed and bulge out vertical to the axis of collision when the yield stress is reached. However, such compression does not go on FOREVER, the bars will eventually break apart when the deformation exceeds the limit in which the ingredients the bar is made of can hold its shape.

The same thing holds true for two pieces of landmass, each piece of landmass can only holds a FINITE amount of energy that is determined by its modulus of elasticity( or more appropriately modulus of bulk for 3D object). In the same manner as the Snickers bar, the energy is held IN the compression/folding of the landmass. In this stress-strain relationship, the landmass will eventually break after the initial deformation when it reaches the "ultimate stress point". If you need more elaboration on this, look up stress-strain curve in a book.

In other word, it doesn't matter how big a landmass it is, everything has a ultimate stress point and will cause the object to buckle eventually. In the case of tectonic activity, the plate initially and gradually stores the energy in the folding at a fault line, once no more energy can be stored the folding part snaps and releases all the energy manifested as earthquake. So there is no such thing as ever-accumulating energy.

After the snap, the landmass is NO LONGER the shape it was and the energy build up from folding will take in possibly a different or same place all over again from SCRATCH. Thus, to answer you question, the energy is only increasing in power FROM zero after each snap. And rememer, the energy stored is in the FOLDING at the fault line and that energy is ALWAYS limited subject to the dimension and material composition at that location doesn't matter if the landmass is the continent of Africa or not.

Answer 2

it's not an indication of impending doom, it has been going on since earth was created, and actually tends to slow with time. truth is that it is a good thing, because without a liquid interior, the earth would loose it's magnetic field, and the solar wind would hit us full force.

at some seams in the tectonic plates, they are being forced apart by magma flowing from the mantle. at other places, the crust is forced under and melts back into the mantle. the process creates mountains, and deep fissures in the ocean. it is analogous to water forming clouds and then raining back down... it is a cycle.

to additional details:
earthquakes are the transformation of power. the cycle has continued for all of earths history, and the size of eathquakes is based mostly on the breaking point of the crust (how much force before there is an earthquake) and so has not significantly changed. most of the land in the world was once connected.

Answer 3

Most of what you are asking is from Geology 101 class. Let me try to answer you from my memory.

(1) What happens to the energy that is created when the tectonic plates crash against or slip by each other?
A - various things: creates mountains, ridges, etc.; earthquakes; tzunami; lava flow; etc.

(2) What would be the ultimate result from that ever-accumulating energy?
A - see above; sometimes it remains dormant and it only affects the severity of the above mentioned occurances.

Answer 4

Yes, there are areas where the tectonic plates move apart (M.O.R.), but there are also areas where the plates move together (subduction zones for example). The tension force that is created leads to volcanic eruptions, earthquakes, and mountain building.

Answer 5

The energy is released in earthquakes.