Meaning and mechanism
The tectonic plates within the lithosphere are relatively mobile and interact with each other at their boundaries. Boundaries are classified as divergent, convergent, and transform, based on the relative movement of the plates.
If the oceanic plate subducts, it can lead to the formation of ocean basins and volcanoes, and the collision of the two continents can result in thick crust and mountain ranges. In a divergent boundary, new oceanic crust is created.
Relationships and conditions
The distribution of deepening earthquakes following the subducted plate indicates the direction of plate subduction. Even with the same convergence boundary, the characteristics differ depending on whether it involves an oceanic plate and a continental plate.
The typical cross-section represents a diagram that summarizes the complex plate boundaries of the actual Earth. It is not possible to determine the timing or magnitude of a specific earthquake simply by looking at the terrain alone.
What to observe in the simulation
Divergence creates ocean ridges and rifts, ocean-continent convergence creates trenches and volcanic arcs, continental collision creates folded mountain ranges, and preservation creates transform faults.
A typical boundary cross section is expressed as a defined shape. Depth and width are different explanatory scales. Continental collision earthquakes are simplified to a thousand earthquakes in this model. We do not predict the actual time and magnitude of an earthquake or the speed of terrain formation.
Key relationships and symbols
Subduction zone: inclined hypocenter distribution approximately 0~700 km
| Symbol | Meaning | Unit |
|---|---|---|
| Divergence | Relative motion in which plates move apart | Direction |
| Convergence and transform motion | Converging motion or sliding along the boundary | Direction |
Worked example
How do earthquake-depth patterns differ between spreading boundaries, transform faults, and subduction zones?
The hypocenter deepens along the subducting oceanic plate. The other boundaries of the model indicate shallow earthquakes within a depth of 70 km.
Common misconceptions
- It is not the case that all convergent boundaries exhibit the same volcanoes, earthquakes, and terrain.