板块运动和地震分类
1. 板块运动
1.1 陆-陆板块（Continental-continental collision）- 造山运动
When two continental plates collide, neither plate is dense enough to subduct into the mantle. Resulting features: Instead, the immense pressure causes the crust to buckle, fold, and push upwards, resulting in the formation of massive, non-volcanic mountain ranges. Example: The Himalayas were formed by the collision of the Indian and Eurasian plates.
1.2 洋-陆板块（Oceanic-continental collision） - 形成俯冲带
In this type of collision, the denser oceanic plate subducts beneath the more buoyant continental plate. Resulting features: The sinking plate creates a deep ocean trench, while magma generated from the melting of the subducting plate rises to form volcanic mountain ranges on the continental plate. Example: The Andes Mountains on the west coast of South America were formed by the Nazca Plate subducting beneath the South American Plate.
1.3 洋-洋板块（Oceanic-oceanic collision）- 形成俯冲带
When two oceanic plates collide, the older, colder, and denser plate will subduct beneath the younger, warmer, and less dense plate. Resulting features: This process creates deep-sea trenches and a line of underwater volcanoes that can eventually grow to form volcanic island arcs. Example: The Mariana Trench and the Mariana Islands were formed by the Pacific Plate subducting under the Philippine Sea Plate.
1.4 离散边界（Divergent boundaries (plates moving apart)）
At divergent boundaries, plates are pulling away from each other, creating new crust as magma from the mantle rises to fill the gap. This process is called seafloor spreading and can occur in both oceanic and continental crust.
- Mid-ocean ridges （洋脊）: In oceanic crust, magma rises to form new oceanic crust and create underwater mountain ranges known as mid-ocean ridges. The Mid-Atlantic Ridge is a prime example.
- Rift valleys （裂谷）: On continents, the pulling-apart motion can cause the crust to stretch and fracture, leading to the formation of a rift valley. The East African Rift Valley is an active example of this process.
1.5 转换边界 （Transform boundaries (plates sliding past each other)）
Transform boundaries are where plates slide horizontally past one another in opposite directions. Crust is neither created nor destroyed at these boundaries, but the immense friction often causes powerful, shallow earthquakes.
- Transform faults: The actual fault where the plates grind past each other is known as a transform fault.
- Example: The most famous transform boundary is the San Andreas Fault in California, where the Pacific Plate is sliding past the North American Plate.
2. 不同板块运动下的地震类型
| Category | Description | Example |
|---|---|---|
| Interplate earthquake | Occurs at the boundary between two tectonic plates, often along subduction zones or transform faults. | 2011 Tohoku earthquake (Japan) |
| Intraslab earthquake | Occurs within the subducting slab itself, usually at depths of 50–300 km. Often caused by slab bending or dehydration. | 2018 Hokkaido Eastern Iburi earthquake |
| Intraplate earthquake | Occurs inside a tectonic plate, away from plate boundaries. Usually rare but can be strong. | 1811–1812 New Madrid earthquakes (USA) |
| Crustal earthquake | Occurs within the Earth’s crust, typically shallower than 30 km. | 1995 Kobe earthquake |
| Subduction interface earthquake | Occurs along the plate interface between a subducting and overriding plate. Often megathrust events. | 2004 Sumatra–Andaman earthquake |
References
[1] At what depth do earthquakes occur? What is the significance of the depth?
[2] 10.4 Plate, Plate Motions, and Plate Boundary Processes