Temblors where Three Plates Meet
2 days ago The movement of the plates creates three types of tectonic boundaries: . Meet the woman who discovered a whole new type of galaxy. While most places have trenches where two large tectonic plates meet, Chile is one of the few places where three major plates meet. In other. When two tectonic plates meet, we get a “plate boundary.” There are three major types of plate boundaries. If two tectonic plates collide, they form a convergent.
The place where one plate subducts beneath another is called a trench. The place where new ocean crust is formed is called a ridge. It can be seen as the recycling of the ocean crust — new ocean crust is formed at the mid-oceanic ridges and is consumed destroyed at the subduction zones trenches.
Sea floor spreading This process of new ocean crust forming at the ridges and moving towards the trenches where it is consumed is the essence of sea floor spreading.
It is because of this reason that the ocean crust is always younger than the continental crust. In general, the rate at which ocean plates move is determined by the rate at which new ocean crust is formed at the ridges. Mid-oceanic ridges are generally located far away from the trenches.
This allows the ocean crust to age a bit before it is consumed at the trenches. However, in the case of Chile, the Chile ridge is located close to the Trench. That is not the only complex tectonic feature.
Chile: where three tectonic plate boundaries meet - The Hindu
The southern Chile triple junction is a magnificent showpiece of a ridge-trench collision. The Chile triple junction region is one of only two presently active examples of a ridge-trench collision.
The other being the west coast of North America; the ridge-trench collision is very prominent along the California continental margin. The Chile Ridge collides with the Chile Trench at a highly oblique angle.
BBC Bitesize - KS3 Geography - Plate tectonics - Revision 2
As the newly produced ocean crust moves parallel to the South American coast, the age of crust becomes progressively older from south to north along the eastern edge of Nazca Plate. There have been 3 instances when the Ridge had collided with the Chile Trench. The relative velocity vector can be oblique to the plate boundary.
F — active faults parallel to the slip vector.
Stability criteria[ edit ] For a triple junction between the plates A, B and C to exist, the following condition must be satisfied: Further conditions must also be met for the triple junction to exist stably — the plates must move in a way that leaves their individual geometries unchanged.
Alternatively the triple junction must move in such a way that it remains on all three of the plate boundaries involved. These criteria can be represented on the same velocity space diagrams in the following way. These lines are the same as those that join points in velocity space at which an observer could move at the given velocity and still remain on the plate boundary.
When these are drawn onto the diagram containing the velocity triangle these lines must be able to meet at a single point, for the triple junction to exist stably.
These lines necessarily are parallel to the plate boundaries as to remain on the plate boundaries the observer must either move along the plate boundary or remain stationary on it.
For a ridge the line constructed must be the perpendicular bisector of the relative motion vector as to remain in the middle of the ridge an observer would have to move at half the relative speeds of the plates either side but could also move in a perpendicular direction along the plate boundary. For a transform fault the line must be parallel to the relative motion vector as all of the motion is parallel to the boundary direction and so the line ab must lie along AB for a transform fault separating the plates A and B.
For an observer to remain on a trench boundary they must walk along the strike of the trench but remaining on the overriding plate. Therefore, the line constructed will lie parallel to the plate boundary but passing through the point in velocity space occupied by the overriding plate.
The point at which these lines meet, J, gives the overall motion of the triple junction with respect to the earth. Using these criteria it can easily be shown why the FFF triple junction is not stable: As faults are required to be active for the purpose of this assessment, an FFF junction can never be stable.
Chile: where three tectonic plate boundaries meet
Types[ edit ] McKenzie and Morgan determined that there were 16 types of triple junction theoretically possible, though several of these are speculative and have not necessarily been seen on earth.
These differences in motion direction affect the stability criteria. Ridge-Ridge-Ridge junctions[ edit ] A map of the Afar triangle in East Africa, another example of an RRR junction and the only triple junction on earth that can be seen above sea level. An RRR junction is always stable using these definitions and therefore very common on earth, though in a geological sense ridge spreading is usually discontinued in one direction leaving failed rift zone.
There are many examples of these present both now and in the geological past such as the South Atlantic opening with ridges spreading North and South to form the Mid-Atlantic Ridgeand an associated aulacogen in the Niger Delta region of Africa. The stability of RRR junctions is demonstrated below — as the perpendicular bisectors of the sides of a triangle always meet at a single point, the lines ab, bc and ca can always be made to meet regardless of relative velocities.
Material for this subduction was provided by a ridge equivalent to the modern East Pacific Rise slightly displaced to the west of the trench. The loss of slab pull caused by the detachment of this lithosphere ended the RTF junction giving the present day ridge — fault system.