Plate Tectonic, Volcanoes and Earthquakes
Transform Plate Boundaries and transform faults. Volcanoes: Articles about volcanoes, volcanic hazards and eruptions past and present. Volcanic activity occurs at two types of plate boundaries: mid-ocean ridges Recall that there are three types of plate boundaries: convergent, divergent, and transform. Their relationship (or lack of one) to the plate tectonic cycle is still being. What is the relationship between volcanoes, earthquakes, and plate-tectonics? Plate tectonics is the over-lying theory presently used by most Earth Scientists to .
The San Andreas Fault system in California exemplifies a side-slipping boundary where the Pacific Plate is moving northwest relative to the North American Plate—a process called strike-slip, or transformfaulting.
The East Pacific Rise is representative of a divergent boundary where the Pacific Plate and the Nazca Plate west of South America are moving apart—a process known as rifting. Volcanoes occur along both subduction and rift zones but are generally absent along strike-slip plate margins. Most subduction-related volcanoes are explosive and build stratovolcanoes, while rift volcanoes tend to be more effusive and build shield volcanoes, though there are exceptions to both these generalities.
Subduction-related volcanoes erupt basaltandesitedaciteand rhyoliteandesite being the predominant rock type. Rift-related volcanoes, especially on the ocean floor, erupt mainly basalt.
The rift volcanoes are largely hidden along the submarine crest of the East Pacific Rise and the Pacific-Antarctic Ridge at depths of 2 to 3 km 1.
Where Does Volcanic Activity Occur?
The Cascade volcanoes in the northwestern United States and the volcanoes in Mexico and Central America are related to the subduction under the North American Plate of the small Juan de Fuca and Cocos plates, which are on the east side of the Pacific Plate. Similarly, the volcanoes of the Andes are related to the subduction of the Nazca Plate beneath the South American Plate.
Conceptual models of how subduction and rift volcanoes may form are shown schematically in the diagram and in the video. Tectonic map showing active volcanoes, plate boundaries, and the Ring of Fire.
Recall that there are three types of plate boundaries: Hot spots or not Hot spot volcanoes occur somewhat randomly around the globe.
The Geological Society
Their relationship or lack of one to the plate tectonic cycle is still being debated. The map below shows several hot spots, but not all the existing ones. In fact, there are over hot spots that have been active sometime during the last 10 million years or so. Notice on the map below that out of the 25 hot spots shown, about 10 occur on top of a mid-ocean ridge. Whether this is a coincidence or not is a current topic of debate among scientists.
World map showing the locations of selected prominent hot spots. This hot, buoyant magma forces its way upward through the overriding crust. As it approaches the surface, the pressure from the overlying rocks decreases, and this allows hot gas to come out of solution, further pressurizing the magma.
Volcanoes and their relation to plate tectonics
When it reaches the surface, a volcano is formed. The magma flows out as lava, sometimes explosively. The majority of the world's volcanoes are associated with subduction zones.
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Since subduction zones represent plate margins, volcanoes tent to occur in lines, like the Cascade Range volcanoes or those on the Aleutian Peninsula. Once in a great while, a new volcano will form. This usually happens when an active underwater volcano produces enough lava to break the surface, such as Surtsey in Iceland in Sometimes a brand new volcano will appear on land, like Paricutin in the Trans-Mexican Volcanic Belt in