What plate movement causes earthquakes?

Answer 1

Generally, any relative movement of tectonic plates causes earthquakes when there is slippage along the plates' transform fault. A plate boundary is usually characterized by what is called a transform fault, and earthquakes occur in fault zones. Seismometers around the world are constantly recording tiny jiggles, which are real earthquakes but mostly too small to be felt by most humans. Many animals are sensitive to small earthquakes, however.

In geology, a fault is any fracture in rock in which one side of the fault has moved in relation to the other. You can observe faults in many places, but most are small and not "active," that is, they do not cause earthquakes. Active faults can move sideways or up and down or both at once. The great majority of faults are of the stick-slip variety, which means that they spend much of their time, sometimes hundred of years stuck at the joint. But the plates on either side of the fault continue to move (it is thought because of convection currents in the mantle rock on which the plates float). At some point, the strain on the stuck portion of a fault becomes too great and the fault slips in some direction. It is that sudden slip that causes the earthquake. Depending upon how much slippage (movement) there is, the resulting earthquake may be larger or smaller.

When one plate dives beneath another that diving action is called subduction. Subduction can cause earthquakes. Also, the diving plate is driven down into the mantle and begins to melt. The melted rock of the subducted plate tends to rise through the rock above like bubbles in boiling water. Those bubbles can become volcanoes. Volcanoes are associated with earthquakes, but again it is movement of the plates that is the ultimate source.

Faults can occur anywhere, not just at existing plate boundaries, but some geologists contend that wherever there is a large fault zone, even if it's in mid continent and nowhere near a plate boundary, there once was a plate boundary there that is marked by the fault. Many of those faults are called suture zones - places where it's thought that there once were plates that are sutured or sewn together. Suture zones can also yield earthquakes.

Another answer: one plate movement that causes earthquakes are when the plates collide from different regions causing either a mountain, volcano, or fault line.

Answer 2

The plate movement is transform. Transform is when two plates slide past eachother, thus causing an earthquake.

Ex. san anderas fault line, California.

answ2. Any inter-plate movement can cause earthquakes. subduction, collision, transform. All may generate stresses in the country rock and when these exceed the strength of the rock, an earthquake results as the rock fails.

Where I live, all the local area, mountains included, moves SW about 40 mm per year. and, about 25km distant is the Alpine Fault (New Zealand). On the other side of which the land is moving N at about 10mm per year. There has been no actual movement of this transform fault for a couple of hundred years, so significant energy is stored up.

We just have to prepare for "the big one", and make sure our emergency supplies are up to date.