Search results
Results from the WOW.Com Content Network
The width of the Cascadia subduction zone varies along its length, depending on the angle of the subducted oceanic plate, which heats up as it is pushed deeper beneath the continent. As the edge of the plate sinks and becomes hotter and more molten, the subducting rock eventually loses the ability to store mechanical stress; earthquakes may ...
As plates sink and heat up, released fluids can trigger seismicity and induce melting within the subducted plate and in the overlying mantle wedge. This type of melting selectively concentrates volatiles and transports them into the overlying plate. If an eruption occurs, the cycle then returns the volatiles into the oceans and atmosphere. [17]
The oceanic Nazca plate subducts beneath the continental South American plate at the Peru–Chile Trench. Just north of the Nazca plate, the oceanic Cocos plate subducts under the Caribbean plate and forms the Middle America Trench. Oceanic crust of the South American plate subducts under the Caribbean plate in the Lesser Antilles subduction zone.
Intermediate-depth earthquakes represent deformation within subducted slabs rather than at the shallow plate interface between subducting and overriding tectonic plates. Typically less damaging on the ground surface above their epicenter than is the case with similar-magnitude shallow-focus earthquakes, but can still be destructive.
A map of the Juan de Fuca plate with noted seismic incidents, including the 2001 Nisqually earthquake. The Juan de Fuca plate is bounded on the south by the Blanco fracture zone (running northwest off the coast of Oregon), on the north by the Nootka Fault (running southwest off Nootka Island, near Vancouver Island, British Columbia) and along the west by the Pacific plate (which covers most of ...
Plate reconstructions time the collision of the Nazca Ridge with the subduction zone at 11.2 Ma at 11 degree S, which implies that the northern extent of the Peruvian flat slab may require some other subducted feature like an oceanic plateau. A putative subducted plateau, the Inca Plateau, has been argued for. [31]
Earthquakes trace the path of the downward-moving plate as it descends into asthenosphere, a trench forms, and as the subducted plate is heated it releases volatiles, mostly water from hydrous minerals, into the surrounding mantle. The addition of water lowers the melting point of the mantle material above the subducting slab, causing it to melt.
The state of Oaxaca lies above the convergent boundary where the Cocos plate is being subducted below the North American plate at a rate of 6.4 cm/yr. The dip of the subducting slab is about 15° as defined by focal mechanisms and earthquake hypocenters. Seismicity in this area is characterised by regular megathrust earthquakes along the plate ...