The fault surfaces are rarely smooth, and pressure may build up when the plates on either side temporarily lock. November 1962. The ground may split; pouring forth molten rock, smoke, and ash that darkens the sky for hundreds of miles. This results in a process known as back-arc spreading, in which a basin opens up behind the island arc.
Seismic Waves More information About Earthquakes. Article Media. The Moho is clearly defined by seismic studies, which detect an acceleration in seismic waves as they pass from the crust into the denser mantle.
Measurements suggest that hotspots may move relative to one another, a situation not predicted by the classical model, which describes the movement of lithospheric plates over stationary mantle plumes. Figure 17.
The molten rock pushes to the surface and cools, contributing to the formation of volcanic mountain ranges. Observations show that most earthquakes are associated with tectonic plate boundaries.
As the plates spread apart magma comes to the surface, although not as explosively as with convergent boundaries. The Ring of Fire is a long horseshoe-shaped earthquake-prone belt of volcanoes and tectonic plate boundaries that fringes the Pacific Ocean basin. Reasoning in an opposite way, the continents might have shifted and rotated, while the pole remained relatively fixed. The supercontinent before Pangaea was Rodinia. Plates sliding past each other cause friction and heat. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article.
Predicting earthquakes. A new continent will form as the Pacific ocean disappears. Conversely, an earthquake may trigger subsequent eruptions. Click here for a handy illustration from the U. Anderson Next Lecture: Brittle earthquake -prone rocks occur only in the shallow crust.
This buildup of stress may be suddenly released in the form of an earthquake. Specifically, they did not see how continental rock could plow through the much denser rock that makes up oceanic crust. The lower mantle is more or less solid, but the region is also very hot, and thus the rocks can flow very slowly a process known as creep.
What drives the movement of tectonic plates? While not as actively or rapidly deforming as the plate boundary in California, Nevada has earthquakes over much larger areas.