This is a continent-continent convergent boundary, and it is generally assumed that although the India Plate continues to move north toward the Asia Plate, there is no actual subduction taking place. There are transform faults on either side of the India Plate in this area.
The entire northern India and southern Asia region is very seismically active. Earthquakes are common in northern India, Nepal, Bhutan, Bangladesh and adjacent parts of China, and throughout Pakistan and Afghanistan.
Many of the earthquakes are related to the transform faults on either side of the India Plate, and most of the others are related to the significant tectonic squeezing caused by the continued convergence of the India and Asia Plates.
That squeezing has caused the Asia Plate to be thrust over top of the India Plate, building the Himalayas and the Tibet Plateau to enormous heights. Most of the earthquakes of Figure The southernmost thrust fault in Figure There is a very significant concentration of both shallow and deep greater than 70 km earthquakes in the northwestern part of Figure This is northern Afghanistan, and at depths of more than 70 km, many of these earthquakes are within the mantle as opposed to the crust.
It is interpreted that these deep earthquakes are caused by northwestward subduction of part of the India Plate beneath the Asia Plate in this area. This map shows the incidence and magnitude of earthquakes in British Columbia over a one-month period in March and April The string of small earthquakes adjacent to Haida Gwaii H. How might these earthquakes be related to that one?
Most of the earthquakes around Vancouver Island V. What is their likely origin? There are three types of plate boundaries: spreading zones, transform faults, and subduction zones. At spreading zones , molten rock rises, pushing two plates apart and adding new material at their edges.
Most spreading zones are found in oceans; for example, the North American and Eurasian plates are spreading apart along the mid-Atlantic ridge. Spreading zones usually have earthquakes at shallow depths within 30 kilometers of the surface.
Illustration of Plate Boundary Types - 95k Transform faults are found where plates slide past one another. An example of a transform-fault plate boundary is the San Andreas fault, along the coast of California and northwestern Mexico. Generally felt. Potentially perceptible. Individual plates of varying size move about the surface of the Earth at varying speeds. Friction causes the plates to get stuck. This causes pressure to build up.
When this stress is realeased an earthquake will occur. Where plates pull apart, slide by each other or collide, there is tectonic activity manifested as earthquakes. The great majority of seismicity on the planet occurs at plate boundaries, although intra-plate seismicity can occur as well when stresses build up in the plate.
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