134 Sentences With "subducts" | Random Sentence Generator

Usually the culprit is a megathrust earthquake, as one tectonic plate slides, or subducts, beneath another.

To the south of the island, ... Caribbean plate upper crust subducts beneath Puerto Rico at the Muertos Trough.

The majority of volcanoes are produced at these tectonic boundaries, either where they move apart, or one subducts under the other.

At a subduction zone, one tectonic plate (in this case the Cocos Plate) goes beneath another (in this case the Caribbean Plate) -- we say it subducts.

The "Cascadia subduction zone" derives its name from the Cascade Range of volcanic mountains that parallel the fault from afar and from how one plate subducts, or goes under, another.

As it subducts beneath the Caribbean Plate, the Cocos Plate warms up, and that water gets released and prompts the upper plate to melt (much like salt prompts ice to melt on the roads), eventually ending up in the newly formed magma.

Initial stage: The oceanic plate subducts on both side, forming two parallel arcs and accretionary wedges with opposing direction.

The Nazca Plate at the Peru-Chile Trench subducts beneath the South America Plate at an average rate of . This subduction occurs at an angle and has generated the Liquiñe-Ofqui fault zone which runs along the volcanic arc. Where the Chile Rise intersects the trench the Nazca Plate ends and the Antarctic Plate begins. This plate also subducts farther south beneath the South America Plate but at a lower pace of .

The oceanic lithosphere subducts at what are known as convergent boundaries. These boundaries can exist between oceanic lithosphere on one plate and oceanic lithosphere on another, or between oceanic lithosphere on one plate and continental lithosphere on another. In the second situation, the oceanic lithosphere always subducts because the continental lithosphere is less dense. The subduction process consumes older oceanic lithosphere, so oceanic crust is seldom more than 200 million years old.

The phenomenon of subduction polarity reversal has been identified in the collision of an intra-oceanic subduction system, which is the collision of two oceanic plates. When two oceanic plates migrate towards each other, one subducts below the other. Generally, the oceanic plate with higher density subducts beneath and the other one overrides the down-going slab. The process continues until a buoyant continental margin sitting on the top of the subducting plate is introduced into the down-going slab.

Innerducts are subducts that can be installed in existing underground conduit systems to provide clean, continuous, low-friction paths for placing optical cables, which have relatively low pulling tension limits. They provide a means for subdividing conventional conduit that was originally designed for single, large-diameter metallic conductor cables into multiple channels for smaller optical cables. Innerducts are typically small-diameter, semi-flexible subducts. According to Telcordia GR-356, there are three basic types of innerduct: smoothwall, corrugated, and ribbed.

This earthquake occurred in the area where the Rivera Plate subducts beneath the North American Plate. It was the result of the relative movements between the North American Plate, the Rivera Plate, and the Cocos Plate.

Japan is on a destructive plate boundary, where the Philippine Plate subducts the Eurasian Plate. It is a triple junction and three subduction zones are involved. After the 2011 Tōhoku earthquake and tsunami, towns like Ishinomaki subsided.

As Africa subducts beneath the Aegean Sea Plate the slab essentially pulls the over-riding plate with it, inducing extension. Rifting occurs as the plate stretches weakening the thickened crust causing its collapse upon itself, creating the basin.

Aerial photo of Solimana (foreground), Coropuna (upper right) and Sabancaya (upper left) The Nazca Plate subducts beneath the South America Plate at a rate of ; it has slowed since the Oligocene. This subduction process is responsible for the formation of the Andes mountains in the region. Together with Sara Sara and Coropuna, Solimana is located on the northwestern end of the Central Volcanic Zone; no volcanism occurs farther north where the Nazca Plate subducts at a shallower angle than beneath the Central Volcanic Zone. Of these volcanoes, Solimana is considered to be the oldest and Coropuna the youngest.

The Australian Plate subducts under the Sunda Plate, creating uplift over much of southern Indonesia, as well as earthquakes at depths of up to . Notable deep- focus earthquakes in this region include a 7.9 earthquake in 1996, and a 7.3 earthquake in 2006.

Northeast China is the site of major Cenozoic volcanism. The Pacific Plate subducts beneath the Eurasian Plate, generating volcanic activity. This subduction process along with back-arc spreading and continental rifting triggers volcanic activity in the region. Geothermal resources are also widespread.

Central Chile lies above the destructive plate boundary where the Nazca Plate subducts beneath the South American Plate. There have been many large earthquakes caused by rupture along the plate interface. Illapel has been struck by major earthquakes in 1730, 1880, 1943 and 2015.

As the central oceanic plate subducts on both sides into the two overriding plates, the subducting oceanic slab brings fluids down and the fluids are released in the mantle wedge. This initiates the partial melting of the mantle wedge and the magma eventually rise into the overriding plates, resulting in the formation of two volcanic arcs on the two overriding plates. At the same time, sediment deposits on the two margins of the overriding plates, forming two accretionary wedges. As the plate subducts and rollback occurs, the ocean becomes narrower and the subduction rate reduces as the oceanic plate becomes closer to an inverted "U" shape.

The earthquake was a strike-slip event that occurred within the Pacific Plate. The epicenter was to the south of the Aleutian Trench, where the Pacific Plate subducts beneath the North American Plate. The region has produced twelve large earthquakes since 1900, including several megathrust earthquakes.

Eclogite is a dense (3.5 g/cu. cm), garnet-bearing rock that is formed as the oceanic crust subducts to zones of high pressure and temperature. The reaction that forms eclogite dehydrates the slab, and hydrates the mantle wedge above. The now denser slab more effectively sinks.

Schematic diagram showing subduction system in conventional plate tectonics theory and divergent double subduction Divergent double subduction (abbreviated to DDS, also called as outward dipping double-sided subduction) is a special type of subduction system where two parallel subduction zones with different directions are developed on the same oceanic plate. In conventional plate tectonics theory, an oceanic plate subducts under another plate and new oceanic crust is generated somewhere else, commonly along the other side of the same plates However, in divergent double subduction, the oceanic plate subducts on two sides. This results in the closure of ocean and arc-arc collision. This concept was first proposed and applied to the Lachlan fold belt in southern Australia.

The Philippine Mobile Belt is bounded on the west by the Manila Trench and its associates the Negros Trench and the Cotabato Trench, which subducts the Sunda Plate under the Philippine Mobile Belt. To the east is the Philippine Trench and its northern associate, the East Luzon Trench which subducts Philippine Sea Plate the Philippine Mobile Belt.Hashimoto, M, ed., (1981) Accretion Tectonics in the Circum- Pacific Regions, p299 The continuity of the Philippine-East Luzon Trench is interrupted and displaced by Benham Plateau on the Philippine Sea Plate,Deschamps and Lallemand (2003) in Intra-Oceanic Subduction Systems: Tectonic and Magmatic Processes p165 which collided and is still colliding with the Sierra Madre of eastern Luzon.

Subduction usually occurs at convergent fault lines. The underlying tectonic plate descends, or subducts, into the Earth's mantle. Earthquakes occurring at these faults are very large in magnitude and scale. In this case the disappearing Arabian plate is part of the oceanic crust while the Eurasia plate is part of the continental crust.

Semeru, or Mount Semeru (Indonesian: Gunung Semeru), is an active volcano in East Java, Indonesia. It is located in the subduction zone, where the Indo- Australia plate subducts under the Eurasia plate . It is the highest mountain on the island of Java. This stratovolcano is also known as Mahameru, meaning 'The Great Mountain.

Philippine Sea plate View of the beach, rocky coastline and the Philippine Sea in Pingtung County, Taiwan The Philippine Sea Plate forms the floor of the Philippine Sea. It subducts under the Philippine Mobile Belt which carries most of the Philippine archipelago and eastern Taiwan. Between the two plates is the Philippine Trench.

Lake Pinatubo in Zambales Luzon is part of the Philippine Mobile Belt, a fast deforming plate boundary zone (Gervasio, 1967) hemmed in between two opposing subduction zones, the west-dipping Philippine Trench-East Luzon Trench subduction zone, and the east-dipping north–south trending Manila Trench- Negros Trench-Cotabato Trench.Hashimoto, M, ed., Accretion Tectonics in the Circum-Pacific Regions, p299 The Philippine Sea Plate subducts under eastern Luzon along the East Luzon Trench and the Philippine Trench, while the South China Sea basin, part of the Eurasian plate, subducts under western Luzon along the Manila Trench. The North-Southeastern trending braided left-lateral strike-slip Philippine Fault System traverses Luzon, from Quezon province and Bicol to the northwestern part of the island.

The Pacific Plate subducts at a pace of about beneath the Okhotsk Plate and Asian Plate. This subduction is responsible for the Kamchatka-Kuril Trench as well as for volcanism in Kamchatka. The Wadati-Benioff Zone lies beneath Kurile Lake. Kurile Lake is included in the Eastern Volcanic Zone of Kamchatka, away from the trench.

As the Pacific Plate subducts beneath the Mariana Plate, it creates a trench. This is the Mariana Trench, and it is the deepest trench in the world. Another result from this subduction are the Mariana Islands. These are formed from dehydration of the subducting, old oceanic crust creates melt, and the melt rises to the surface through a volcano.

When oceanic lithosphere and continental lithosphere collide, the dense oceanic lithosphere subducts beneath the less dense continental lithosphere. An accretionary wedge forms on the continental crust as deep-sea sediments and oceanic crust are scraped from the oceanic plate. Volcanic arcs form on continental lithosphere as the result of partial melting due to dehydration of the hydrous minerals of the subducting slab.

Some lithospheric plates consist of both continental and oceanic crust. Subduction initiates as oceanic lithosphere slides beneath continental crust. As the oceanic lithosphere subducts to greater depths, the attached continental crust is pulled closer to the subduction zone. Once the continental lithosphere reaches the subduction zone, subduction processes are altered as continental lithosphere is more buoyant and resists subduction beneath other continental lithosphere.

The modern Chilean subduction is thought to be a parallel model of the Sevier and Laramide events so there are possibly answers to this question in this modern model. Explanations may include a combination of plate motion rates increasing, the underriding oceanic plate becoming younger as the older portion subducts, and thus the underriding plate being hotter and more buoyant.

Order of subduction control the geometry of divergent doubled subduction. The side that begins to subduct earlier enters the eclogitization level earlier. The density contrast between the plate and the mantle increases which makes the sinking of the plate faster, creating a positive feedback. It results in an asymmetrical geometry where the slab length is longer on the side which subducts earlier.

Sunspots can form on the Sun's surface, which can cause greater variability in the emissions that Earth receives. Volcanoes form when two plates meet and one subducts underneath the other. They thus form along most plate boundaries; the Ring of Fire is an example of this. The study of volcanoes along plate boundaries has shown a correlation between eruptions and climate.

At the Izu-Bonin-Mariana volcanic arc, the Pacific Plate subducts beneath the Philippine Plate. The subduction of the old Pacific Plate releases fluids from the downgoing slab into the mantle. The interaction between these fluids and the mantle fertilizes the latter and results in volcanic activity. Compared to ocean island volcanoes, these volcanoes are longer lived and produce more gas-rich magma.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of . This subduction process has been ongoing since the Jurassic. Neighbouring volcanic centres to Wheelwright include Ojos del Salado farther south. The caldera is set into a terrain formed by volcanic rocks of Miocene-Pliocene age, chiefly lava flows of andesitic-dacitic composition.

Image of earthquakes occurring in and around Russia since 1900. Note that most of this seismicity is in the Kamchatka area. Three earthquakes, which occurred off the coast of Kamchatka Peninsula in far eastern Russia in 1737, 1923 and 1952, were megathrust earthquakes and caused tsunamis. They occurred where the Pacific Plate subducts under the Okhotsk Plate at the Kuril-Kamchatka Trench.

Fiji is located on the northeast corner of the Indo-Australian Plate near where it subducts under the Pacific Plate on the North Fiji Basin microplate between the North Fiji Fracture Zone on the north and the Hunter Fracture Zone on the south. It is part of the Ring of Fire, the string of volcanoes around the boundary of the Pacific Ocean.

Volcanic activity in the Andes occurs in four regions, the Northern Volcanic Zone, the Central Volcanic Zone, the Southern Volcanic Zone and the Austral Volcanic Zone. The first three of these are found where the Nazca Plate subducts beneath the South America Plate, while the last zone occurs at the subduction zone of the Antarctic Plate.Báez et al. 2017, p.

The Japan Trench is created as the oceanic Pacific Plate subducts beneath the continental Okhotsk Plate. The continuous subduction process causes frequent earthquakes, tsunami and stratovolcanoes. The islands are also affected by typhoons. The subduction plates have pulled the Japanese archipelago eastward, created the Sea of Japan and separated it from the Asian continent by back-arc spreading 15 million years ago.

Peru lies above the destructive plate boundary where the Nazca Plate subducts beneath the South American Plate. The plates converge at a rate of 70 mm per year. The country has been affected by many large megathrust earthquakes caused by slip along the plate interface, such as the 1868 Arica earthquake. There are also large earthquakes of intermediate depth caused by faulting within the downgoing Nazca Plate.

The Woodlark Plate is a small tectonic plate located in the eastern half of the island of New Guinea. It subducts beneath the Caroline plate along its northern border while the Maoke Plate converges on the west, the Australian plate converges on the south, and on the east an undefined compressive zone which may be a transform fault marking the boundary with the adjoining Solomon Sea Plate.

This is known as bioturbation, which stimulates mineralization of organic matter and the release of nutrients (Hansen et al. 1998; Lohrer et al. 2004; D’Andrea and DeWitt 2009), thereby affecting the growth of phytoplankton in the pelagic zone (Welsh 2003). Bioturbation by macrofauna affects sediment permeability and water content, destabilizes chemical gradients, subducts organic matter, and influences rates of remineralization and inorganic nutrient flux.

In the Lau Basin east of the NFB the Pacific plate is subducting westward under Tonga trench in the highest rate of back-arc rifting known — where the Louisville seamount chain subducts under the Tonga trench rifting propagates at . This seamount chain–trench intersection propagates southward at a rate of and, as a consequence, Tonga Islands rotate clockwise at a rate of 9.3°/Ma.

Oxidation of Price's volcanic rocks has given the mountain a red colour. Like other volcanoes in the Garibaldi Volcanic Belt, Mount Price formed as a result of subduction zone volcanism. As the Juan de Fuca Plate subducts under the North American Plate at the Cascadia subduction zone, it forms volcanoes and volcanic eruptions. Unlike most subduction zones worldwide, there is no deep oceanic trench present along the continental margin in Cascadia.

The CVZ is located between 16° and 28° southern latitude, on the western margin of South America. At this latitude, west of the CVZ, the oceanic Nazca Plate subducts steeply beneath the continental South America Plate in the Peru–Chile Trench. East of the CVZ lies the Altiplano, a plateau with average elevations of . The CVZ contains about 1,100 volcanoes of Cenozoic age, including Parinacota, San Pedro and Tata Sabaya.

Monte Burney seen from space Monte Burney is the most southern stratovolcano of the Austral Volcanic Zone. Six Quaternary volcanoes form this long volcanic arc. The Antarctic Plate subducts beneath the South America Plate and the Scotia Plate at a pace of about , causing the volcanism. The young age of the subducting crust (12-24 million years old) gives the volcanic rocks a unique chemical composition including adakitic rocks.

Chances Peak is the culminant point of the active complex stratovolcano named Soufrière Hills. It is the highest point in Montserrat, a British overseas territory located in the Caribbean Sea. Chances Peak is on a destructive plate margin. The volcano itself is in the middle Caribbean plate, but this is because the North American Plate and the Atlantic Plate subducts beneath it, causing a buildup of pressure to form a volcano.

The Pacific plate subducts in the IBM trench, so understanding what is subducted beneath IBM requires understanding the history of the western Pacific. The IBM arc system subducts mid-Jurassic to Early Cretaceous lithosphere, with younger lithosphere in the north and older lithosphere in the south. It is not possible to directly know the composition of subducted materials presently being processed by the IBM Subduction Factory – what is now 130 km deep in the subduction zone entered the trench 4 – 10 million years ago. However, the composition of the western Pacific seafloor-oceanic crust – sediments, crust, and mantle lithosphere – varies sufficiently systematically that, to a first approximation, we can understand what is now being processed by studying what lies on the seafloor east of the IBM trench. The Pacific plate seafloor east of the IBM arc system can be subdivided into a northern portion that is bathymetrically ‘smooth’ and a southern portion that is bathymetrically rugged, separated by the Ogasawara Plateau.

Once this water comes into contact with the warmer atmosphere, the anthropogenic carbon (CO2) and heat is absorbed into the ocean. The now warm and carbon containing surface water is then moved by means of the Ekman transport. Along with this transport, nutrients are brought along to lower latitudes where the ecosystems depend on them. After the transport, the water subducts, where the carbon and heat mix with the deeper mixed layers.

Volcanism in the Chilean Andes is caused by subduction of the Nazca and Antarctic tectonic plates under the South American Plate. Volcanoes in Chile occur in the Central (CVZ), South (SVZ), and Austral Volcanic Zones (AVZ). The gap that separates the Central and South Volcanic Zones is caused by shallow-angle subduction in the Pampean flat-slab segment where the more buoyant Juan Fernández Ridge subducts under the South American continent.Stern et al.

In the Makran region, the Arabian Plate subducts beneath the Eurasian Plate at ~4cm/yr. This subduction is associated with an accretionary wedge of sediments which has developed since the Cenozoic. To the west, the Makran Trench is connected by the Minab Fault system to the Zagros fold and thrust belt. To the east, the Makran Trench is bounded by the transpressional strike-slip Ornach-Nal and Chaman Faults, which connect to the Himalayan orogeny.

Volcanism and tectonism in the Central Andes has been ongoing since the late Oligocene. Volcanism has been occurring in two broad regions, the principal volcanic arc and a secondary volcanic arc in the Cordillera Oriental whose origin is less clear. In that area, the Brazilian Shield subducts beneath the Andean orogen. The origin of the Macusani volcanics has been variously attributed to frictional heating of the subducting Brazilian shield, the subduction itself or a hotspot.

Nabesna Glacier The southern part of Alaska is composed of a series of terranes that have been pushed against the North American landmass by the action of plate tectonics. The Pacific Plate moves northwestward relative to the North American Plate at about to per year,Winkler, p. 12. meeting the continental landmass in the Gulf of Alaska. The Pacific Plate subducts under the Alaskan landmass, compressing the continental rocks and giving rise to a series of mountain ranges.

The park's volcanoes are the southern end of a 2500 km long range of volcanoes, below which the Australian Plate meets the Pacific Plate. These volcanoes have resulted from internal tectonic processes. The Pacific Plate subducts under the Australian plate, and subsequently melts due to the high temperatures of the aesthenosphere. This magma being less dense, rises to the surface and goes through the weak parts of the Earth's crust (the faults) resulting in volcanic processes in the area.

At the southern end of South America, the Antarctic Plate subducts beneath South America at a rate of in the Peru-Chile Trench. This subduction process has caused adakitic volcanism on the western margin of southernmost South America, forming the Austral Volcanic Zone. Patagonia is a region where four tectonic plates, the Antarctic Plate, the Nazca Plate, the Scotia Plate and the South America Plate, interact. Starting 4million years ago the Chile Rise collided with the Peru- Chile Trench.

The northern margin of the Chortis Block is the Motagua- Polochic fault of the North American-Caribbean strike-slip boundary. The Cocos/Farallon Plate subducts beneath its western margin resulting in the Middle America Trench and the Central America Volcanic Arc. Miocene-Holocene- aged rifts in the northern and western Chortis Block is the result of slow internal deformation. The southern and eastern extent is roughly the Nicaragua-Costa Rica border and the offshore Hess Escarpment.

The shallow earthquake was the result of thrust faulting on the Aleutian subduction zone where the Pacific plate subducts underneath the North American plate, forming the Aleutian Trench and Arc. This convergent boundary is one of the most active in the world, and was the location of the 1964 Alaska earthquake; the largest recorded in North America, and the second largest in the world. On average, the rate at which these plates converge is about 64 mm/year.

Japan subduction setting. The discovery of LFEs originates in Japan at the Nankai trough and is in part due to the nationwide collaboration of seismological research following the Kobe earthquake of 1995. Low frequency earthquakes in Japan were first observed in a subduction setting where the Philippine Sea plate subducts at the Nankai trough near Shikoku. The low-frequency continuous tremor researchers observed was initially interpreted to be a result of dehydration reactions in the subducting plate.

West of South America, the Nazca Plate subducts beneath the South America Plate. This process has formed the Andean Volcanic Belt, which is subdivided into the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone. These belts have different underlying crusts and thus have different typical magma compositions. These volcanic zones are separated from each other by zones where there is no volcanism, associated with a shallow dip of the seismic zone of the subducting plate.

Such a variety of volcanic rocks has been found at the adjacent volcanic fields of Ayutla, Los Volcanes and Tapalpa. As a plate subducts and sinks into the mantle, it loses water to the abovelying mantle wedge. This water also transports material from the subducting slab into the mantle wedge, modifying its chemistry. The melting of this modified mantle wedge appears to be the source of Mascota magmas, albeit with some magmas being modified by interactions with the crust.

The Nazca plate subducts beneath the South America plate at a speed of per year in the area of the Central Volcanic Zone. The subduction results in volcanism along the occidental Cordillera east of the trench formed by the subduction. Incapillo is one of at least six different ignimbrite or caldera volcanoes that are part of the Central Volcanic Zone, in Chile, Bolivia and Argentina. The Central Volcanic Zone is one of four different volcanic arcs in the Andes.

The Nazca Plate subducts beneath the South America Plate, giving rise to the volcanism in the Andean Central Volcanic Zone, including mafic back-arc volcanism which is often associated with tectonic lineaments. Los Gemelos () and El Saladillo () lie in the Calchaqui Valley, close to the towns of La Poma and El Saladillo. The valley is bordered by two thrust faults, at least one (the Calchaqui fault) of which has had historical earthquakes; the Los Gemelos volcanic cones were constructed along the fault.

At this point, the India Plate subducts beneath the Burma Plate, which carries the Nicobar Islands, the Andaman Islands, and northern Sumatra. The India Plate sinks deeper and deeper beneath the Burma Plate until the increasing temperature and pressure drive volatiles out of the subducting plate. These volatiles rise into the overlying plate, causing partial melting and the formation of magma. The rising magma intrudes into the crust above and exits the Earth's crust through volcanoes in the form of a volcanic arc.

Strain rate and hydrologic properties also influence the strength of the accretionary prism and the angle of critical taper. Fluid pore pressures modify rock strength. Low permeability and rapid convergence may result in pore pressures that exceed lithostatic pressure and thus a relatively weak accretionary prism with a shallowly tapered geometry, whereas high permeability and slow convergence result in lower pore pressure, stronger prisms, and steeper geometry. The Hellenic Trench of the Hellenic arc system is unusual because this convergent margin subducts evaporites.

Off southwesternmost South America, the Antarctic Plate subducts beneath the South America Plate at a rate of . This subduction is responsible for the volcanism in the Austral Volcanic Zone, whereas earthquake activity is low; this is possibly because the subducting plate is too hot and too slow moving. The basement below Aguilera is of Paleozoic-early Mesozoic age and consists of metamorphic rocks. The volcano sits at the easterly margin of the Patagonian Batholith, a Mesozoic-Cenozoic igneous rock province.

The islands consist of two concentric island arcs. The Inner Banda Arc is made up of young, active volcanic islands, including the Banda Islands, Serua Island, Nila Island, Teun Island, Damar Island, and Romang Island. The Outer Banda Arc is made up of oceanic sediments, principally coralline limestone, together with some older metamorphic rocks which accreted as the Australian Plate subducts under the Banda Sea Plate. The Outer Banda Arc includes the Kai Islands, Tanimbar Islands, Babar Islands, and Leti Islands.

The Pacific Plate subducts westward beneath the Australian Plate along the ridge. It is divided into two segments, the northern Tonga Ridge and southern Kermadec Ridge, by the Louisville Seamount Chain. On its western side, the ridge is flanked by two back-arc basins, the Lau Basin and Havre Trough, that began opening at 6 and 2 Ma respectively. Together with these younger basins the ridge forms the eastward- migrating, 100 Ma-old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex.

The Mariana chain of which Guam is a part was created by collision of the Pacific and Philippine Sea tectonic plates. Guam is the closest land mass to the Mariana Trench, the deep subduction zone that runs east of the Marianas. Due to its location on the Mariana Plate just westward of where the Pacific Plate subducts the Mariana and the Philippine Sea Plates, Guam occasionally experiences earthquakes. In recent years, most with epicenters near Guam have had magnitudes ranging from 5.0 to 8.7.

Hualca Hualca (possibly from Aymara and Quechua wallqa collar) is an extinct volcano in Arequipa Region in the Andes of Peru. It has a height of 6,025 metres. Hualca Hualca is part of the Central Volcanic Zone of the Andes, a volcanic belt which occurs where the Nazca Plate subducts beneath the South America Plate. Volcanoes in Peru that are part of the Central Volcanic Zone include Ampato, Casiri, Chachani, Coropuna, El Misti, Huaynaputina, Pichu Pichu, Sabancaya, Sara Sara, Solimana, Ticsani, Tutupaca, Ubinas and Yucamane.

Unlike one sided subduction where only one magmatic arc is generated on the overriding plate, two parallel magmatic arcs are generated on both colliding overriding plates when the oceanic plate subducts on two sides. Volcanic rocks indicating arc volcanism can be found on both sides of the suture zone. Typical rock types include calc-alkaline basalt, andesites, dacite and tuff. These arc volcanic rocks are enriched in Large Ion Lithophile Element (LILE) and Light Rare Earth Element (LREE) but depleted in niobium, hafnium and titanium.

Beneath northern Chile, the Nazca Plate subducts beneath the South America Plate. This subduction process is responsible for volcanic activity in the Western Cordillera, as well as elsewhere in the Andes. The volcanoes of Chile are part of the Pacific Ring of Fire, which in Chile contains about 2000 volcanoes over a length of . In Chile, it is subdivided into two volcanic zones, the Central Volcanic Zone which also spans Peru, Bolivia and Argentina, and the Southern Volcanic Zone which spans Chile and Argentina.

Cuauhtzin lava dome, of the Sierra Chichinautzin volcanic field. The Sierra Chichinautzin volcanic field, also known as El Pedegral, is located in the Trans-Mexican Volcanic Belt, approximately from where the Cocos Plate subducts beneath the North American Plate.Heterogeneous magmas of the Quaternary Sierra Chichinautzin Volcanic Field (central Mexico): the role of an amphibole- bearing mantle and magmatic evolution processes. Magmas heterogéneos del campo volcánico Cuaternario de la Sierra de Chichinautzin (México central): el papel de un manto con anfíbol y los procesos de evolución magmática.

Ophiolite generation and subduction may also be explained, as suggested from evidence from the Coast Range ophiolite of California and Baja California, by a change in subduction location and polarity.Wakabayashi, J. and Dilek, Y., (2000) Oceanic crust attached to a continental margin subducts beneath an island arc. Pre-ophiolitic ocean crust is generated by a back-arc basin. The collision of the continent and island arc initiates a new subduction zone at the back-arc basin, dipping in the opposite direction as the first.

Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the oceanic plate subducts, or submerges, under the continental plate, forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, thus creating magma. This magma tends to be extremely viscous because of its high silica content, so it often does not attain the surface but cools and solidifies at depth.

The New Hebrides central chain stretches from Ureparapara island, Banks Islands, in the north to Hunter island in the south. The New Hebrides trench retreats progressively which causes the southern end the subduction zone to bend eastward. The Australian plate subducts under Vanuatu at the New Hebrides trench which results in a complex of rifts and transforms in the NFB. The New Hebrides island chain itself is being deformed as buoyant features such as d'Entrecasteaux Ridge and West Torres Plateau are being subducted in this process.

To the north it collides with the Pacific Plate and the Caroline Plate, part of the western part subducts under the Woodlark Plate of New Guinea, and it is separated from the South Bismarck Plate by a divergent boundary called Bismarck Seismic Sea Lineation (BSSL). The plate is moving easterly along with the Pacific plate. It is in a very seismically active area. Between the plate and the Caroline Plate is the Manus Trench and between the plate and the Pacific plate is the Kilinailai Trench.

The volcanic activity that results as the Indo-Australian Plate subducts the Eurasian Plate has created the Sunda Arc. As well as the sideways movement between the plates, the 2004 Indian Ocean earthquake resulted in a rise of the seafloor by several metres, displacing an estimated of water and triggering devastating tsunami waves. The waves radiated outwards along the entire length of the rupture (acting as a line source). This greatly increased the geographical area over which the waves were observed, reaching as far as Mexico, Chile, and the Arctic.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about . This subduction process is responsible for the volcanism in the Andean Volcanic Belt, which occurs in a Northern Volcanic Zone in Ecuador and Colombia, a Central Volcanic Zone in Peru, Bolivia, Chile and Argentina and a Southern Volcanic Zone in Chile and Argentina. These volcanic zones are separated by gaps without volcanism, where the subduction process is shallower. Several phases of tectonic and volcanic activity have been identified in the Central Volcanic Zone.

The Earth's surface or lithosphere comprises tectonic plates which average approximately 50 miles in thickness, and are continuously moving very slowly upon a bed of magma in the asthenosphere and inner mantle. The plates converge upon one another, and one subducts below the other, or, where there is only shear stress, move horizontally past each other (see transform plate boundary below). Little movements called fault creep are minor and not measurable. The plates meet with each other, and if rough spots cause the movement to stop at the edges, the motion of the plates continue.

These gaps are not static; the gap separating the Austral and the Southern Volcanic Zones has been moving northward for the past 15-20 million years. The Southern Volcanic Zone itself is subdivided into additional volcanic zones, the Northern, Transitional, Central and Southern Southern Volcanic Zone and contains over two calderas and over 60 volcanoes with Quaternary activity. More volcanoes in the neighbourhood of Mentolat include Melimoyu and Cay to the north, Maca and Cerro Hudson to the south, as well as several monogenetic volcanoes. South of Hudson, the Chile Rise subducts in the trench.

The ridge is buoyant, resulting in flat slab subduction of the Nazca Plate underneath Peru. Buoyancy is related to crustal age, and the buoyancy effect can be seen in oceanic crust aged from 30-40 Ma. The Nazca Plate is dated to 45 Ma where it subducts into the Peru-Chile trench. The extreme thickness of the buoyant ridge is responsible for the flat slab subduction of the older underlying plate. Modeling has shown that this type of subduction is only concurrent with submarine ridges, and accounts for approximately 10% of convergent boundaries.

South of the Chile Triple Junction, the Antarctic Plate subducts beneath the South America Plate at a rate of . This subduction process is responsible for volcanic activity in the Austral Volcanic Zone; south of the southernmost volcano of this zone, Fueguino, the subduction gives way to strike-slip faulting. This subduction process is not accompanied by much earthquake activity. Not all volcanism at these latitudes was triggered by subduction; during the Miocene the Chile Rise was subducted here and this caused a temporary pause of the subduction process and the formation of a slab window.

The Gulf of Corinth is an area of active extensional tectonics. The underlying cause of this extension has been attributed to rollback of the African Plate as it subducts northwards beneath the Aegean Plate. Other possible mechanisms include gravitational collapse of crust overthickened during the Paleogene to early Neogene or the affects of the continuing propagation of the North Anatolian Fault towards the southwest. The rift that formed the Gulf of Corinth is bounded by large normal faults that vary in their polarity (dip direction) along its length.

Java is between Asia and Australia at the centre of the Indonesian archipelago where the Indo-Australian Plate subducts beneath the Eurasian Plate. There has been subduction at the Java Trench since the Early Cenozoic. An Eocene to Early Miocene volcanic arc in East Java, the Southern Mountains Arc, is parallel to and south of the modern arc. Thick volcanic and volcaniclastic deposits related to this arc are well preserved in East Java and identified volcanic centres are separated by similar distances to volcanoes of the modern arc.

From Fiordland south, the Australian Plate subducts under the Pacific Plate forming the Puysegur Trench.Diagram showing the Australian- Pacific Plate Boundary This configuration has led to volcanism and extension in the North Island forming the Taupo Volcanic Zone and uplift in the South Island forming the Southern Alps. The Pacific Plate is colliding with the Australian Plate at a rate of about 40 mm/yr. The East coast of the North Island is being compressed and lifted by this collision, producing the North Island and Marlborough Fault Systems.

Off the western coast of South America, the oceanic Nazca Plate subducts beneath the South America Plate in the Peru-Chile Trench. Volcanism associated with subduction in the region has been ongoing since the Jurassic. Dehydration of the downgoing slab causes melts to form in the abovelying asthenosphere which drive the activity in the volcanic arc. East of the main volcanic arc of the Central Volcanic Zone the back-arc region has been volcanically active since the Oligocene, generating volcanic edifices ranging from small monogenetic volcanoes to large calderas with their ignimbrites.

This is likely due to the difference in subduction geometries between the two plates. The Philippine Sea plate at the Nankai trough subducts at shallower overall angles than does the Pacific plate at the Japan Trench, thereby making the Japan trench less suitable for SSEs and LFEs. LFEs in Japan have hypocenters located near the deepest extent of the transition zone, down- dip from the seismogenic zone. Estimates for the depth occurrence of the seismogenic zone near Tokai, Japan are 8–22 kilometers as determined by thermal methods.

The geology of the Landels- Hill Big Creek Reserve is unique. There are depositions of sea floor deposits from the Cretaceous age, as well as Franciscan Complex, a medley of rock scraped off the oceanic crust as the Pacific Plate subducts beneath the North American Plate. In the midst of this, there is also a Granitoid Salinia. This Salinia is thought to have originated in the Southern Sierra Nevada range some 100 million years ago,Norris, R. 1985, Geology of the Landels-Hill Big Creek Reserve, Monterey County, California.

300px The Chile Rise or Chile Ridge is an oceanic ridge, a tectonic divergent plate boundary between the Nazca and Antarctic plates. Its eastern end is the Chile Triple Junction where the Chile Rise is being subducted below the South American Plate in the Peru–Chile Trench. It runs westward to a triple point south of the Juan Fernández Microplate where it intersects the East Pacific Rise. The Chile Rise subducts near Taitao Peninsula where Taitao ophiolite and other geolical features are associated to the interactions at the triple junction.

The Louisville Ridge, also known as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts in the Southwest Pacific Ocean. As one of the longest seamount chains on Earth it stretches some Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; and Lonsdale, P. F. (2007). Geochemical Evolution of the Louisville Seamount Chain, American Geophysical Union, Fall Meeting 2007, abstract #V42B-06. from the Pacific-Antarctic Ridge northwest to the Tonga-Kermadec Trench, where it subducts under the Indo-Australian Plate as part of the Pacific Plate.

The Louisville hotspot has produced the Louisville Ridge, which is one of the longest seamount chains on Earth, stretching some Vanderkluysen, L.; Mahoney, J. J.; Koppers, A. A.; and Lonsdale, P. F. (2007). Geochemical Evolution of the Louisville Seamount Chain, American Geophysical Union, Fall Meeting 2007, abstract #V42B-06. from the Pacific-Antarctic Ridge where it subducts under the Indo-Australian Plate as part of the Pacific Plate. The Louisville hotspot is believed to have been active since at least 78.8 ± 1.3 Ma based on age of the age of the oldest seamount (Osbourn ).

The accreted material is often referred to as an accretionary wedge, or prism. These accretionary wedges can be identified by ophiolites (uplifted ocean crust consisting of sediments, pillow basalts, sheeted dykes, gabbro, and peridotite). Subduction may also cause orogeny without bringing in oceanic material that collides with the overriding continent. When the subducting plate subducts at a shallow angle underneath a continent (something called "flat-slab subduction"), the subducting plate may have enough traction on the bottom of the continental plate to cause the upper plate to contract leading to folding, faulting, crustal thickening and mountain building.

As one plate subducts, it sets up convection currents in the upper mantle that exert a net trenchward pull, and acts to suck both the plates together. Slab suction compared to slab pull is weaker, but not as much you might expect, considering slab pull is the strongest of the driving forces. When measuring the forces of these two mechanisms, slab pull in subducting plate boundaries for upper mantle slabs is 1.9 × 10^21 N. In comparison slab suction in the upper and lower mantle totaled 1.6 × 10^21 N.Conrad, C. P.; Lithgow-Bertelloni, C (2002). "How Mantle Slabs Drive Plate Tectonics". Science.

Depending on assumptions, this part of the boundary accommodates 134–139 mm per year of relative plate motion. The southern boundary of the Bismarck Sea Plate is formed by a convergent boundary where oceanic crust of the Solomon Sea Plate is subducting northwards along the New Britain Trench, forming the New Britain island arc. It is unclear how these two boundaries link together, as the Weitin Fault becomes difficult to trace southeast of New Ireland. To the southeast, the New Britain Trench links to the Solomon Islands Trench along which the Solomon Sea Plate subducts beneath the Pacific Plate.

Coastal parts of Ecuador and southern Colombia lie above the convergent boundary where the Malpelo Plate subducts beneath the South American Plate along the Colombia–Ecuador Trench. At this location the Malpelo Plate, the microplate northeast of the Nazca Plate, is moving to the east relative to South America at a rate of 58 mm per year. North of the Carnegie Ridge, the subduction interface has four recognisable segments, from south to north, the Esmeraldas, Manglares, Tumaco and Patia segments. This plate boundary has been the location of several great historical earthquakes, most associated with damaging tsunamis.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about . This subduction process is responsible for the volcanic activity in the Andes. The subducting slab releases fluids which induce the formation of melts which are then erupted on the surface as volcanism. The subduction process is not uniform along the plate margin; variations in the dip of the subducting Nazca plate occur along its length, and volcanic activity is concentrated in three belts (Northern Volcanic Zone, Central Volcanic Zone and Southern Volcanic Zone) where the angle of subduction is steep enough.

It links the Kuril-Kamchatka Trench to the north and the Izu- Ogasawara Trench to its south with a length of . This trench is created as the oceanic Pacific plate subducts beneath the continental Okhotsk Plate (a microplate formerly a part of the North American Plate). The subduction process causes bending of the down going plate, creating a deep trench. Continuing movement on the subduction zone associated with the Japan Trench is one of the main causes of tsunamis and earthquakes in northern Japan, including the megathrust Tōhoku earthquake and resulting tsunami that occurred on 11 March, 2011.

Off the southwestern coast of South America, the Nazca Plate subducts beneath the South America Plate in the Peru-Chile Trench, at a rate of . This subduction process is responsible for the growth of the Andes and for volcanism in the region; the oblique character of subduction has further led to the onset of strike-slip faulting. Ticsani is grouped together with the neighbouring volcanoes Huaynaputina and Ubinas, given their tectonic context, which is unusual for Peruvian volcanoes and shared geochemical traits. Huaynaputina had a large eruption in 1600 and Ubinas is presently the most active volcano in southern Peru.

A delay in eclogitization could arise through the subduction of zone thicker oceanic lithosphere without deeply penetrating faults. Oceanic crust is normally faulted at the trench rise by the bending of the plate as it subducts. This may be an effect or a cause of flat slab subduction, but it seems as though it is more likely an effect. A resumption of normally dipping subduction beyond the flat slab portion is associated with the eclogite reaction, and the amount of time needed to accumulate enough eclogite for the slab to start sinking may be what limits temporal scale of flat slab subduction.

Volcanism in the Andes is caused by the subduction of the Nazca Plate and the Antarctic Plate beneath the South America Plate. The Nazca Plate subducts at a speed of and the Antarctic Plate at a speed of . Volcanism does not occur along a continuous chain; there are four separate regions named: the Northern Volcanic Zone, the Central Volcanic Zone, the Southern Volcanic Zone, and the Austral Volcanic Zone. The formation of magma results from the release of water and other volatile material from the subducting plate, which is then injected into the above-lying mantle wedge.

Extension further occurred during the Pleistocene in the adjacent Mexican mainland in the Tepic-Zacoalco rift, which separates the Jalisco block from the Sierra Madre Occidental, and the Colima rift zone with its probable submarine extension, the Manzanillo canyon. Volcanism and earthquake activity is still ongoing in these rift zones today, forming for example Ceboruco and Volcan Colima which is Mexico's most active volcano. These two rift zones together with the Middle America Trench delimit the Jalisco block. At the same time, the Rivera Plate subducts beneath the Jalisco block, causing earthquakes such as the 1932 Mexico earthquake.

Most of the relative motion between the Pacific and Eurasia plates is accommodated approximately to the east-southeast of the epicenter of the earthquake, where the Pacific Plate subducts beneath the Okhotsk Plate. This shallow crustal earthquake was followed 13 hours later by a deep focus magnitude 6.8 quake roughly to the west, below the Sea of Japan. The two earthquakes were generated by different mechanisms. The first earthquake was caused by deformation within the crust of the Okhotsk Plate and the second quake was likely caused by faulting resulting from internal deformation of the subducted Pacific Plate.

Epicenter and associated aftershocks The 2004 Indian Ocean earthquake was unusually large in geographical and geological extent. An estimated of fault surface slipped (or ruptured) about along the subduction zone where the Indian Plate slides (or subducts) under the overriding Burma Plate. The slip did not happen instantaneously but took place in two phases over several minutes: Seismographic and acoustic data indicate that the first phase involved a rupture about long and wide, beneath the sea bed—the largest rupture ever known to have been caused by an earthquake. The rupture proceeded at about , beginning off the coast of Aceh and proceeding north-westerly over about 100 seconds.

In the Peru-Chile Trench, the Nazca Plate subducts beneath the South American Plate at a rate of about , leading to volcanic activity at distances of from the trench. Research indicates that subduction has been ongoing since the Jurassic 200 million years ago but accelerated 26 million years ago. After a phase of andesitic volcanism lasting from the late Tertiary to the Miocene, large scale ignimbritic volcanism commenced about 23 million years ago and is still ongoing. It began north of 21° southern latitude with the 23-18 million years old Oxaya formation and the 15–17 million years old Altos de Pica formation.

Other volcanoes in the region include Agung, Batur, and Bratan, on the island of Bali to the west. Location of Lombok Lombok is one of the Lesser Sunda Islands in the Sunda Arc of Indonesia, a subduction zone where the Australian plate subducts beneath the Eurasian plate at a rate of . The magmas feeding Mount Samalas and Mount Rinjani are likely derived from peridotite rocks beneath Lombok, in the mantle wedge. Before the eruption, Mount Samalas may have been as tall as , based on reconstructions that extrapolate upwards from the surviving lower slopes; its current height is less than that of the neighbouring Mount Rinjani, which reaches .

Obduction is the overthrusting of continental crust by oceanic crust or mantle rocks at a convergent plate boundary, such as closing of an ocean or a mountain building episode. This process is uncommon because the denser oceanic lithosphere usually subducts underneath the less dense continental plate. Obduction occurs where a fragment of continental crust is caught in a subduction zone with resulting overthrusting of oceanic mafic and ultramafic rocks from the mantle onto the continental crust. Obduction often occurs where a small tectonic plate is caught between two larger plates, with the crust (both island arc and oceanic) welding onto an adjacent continent as a new terrane.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of . This subduction process is responsible for volcanism in the Central Volcanic Zone and started during the Jurassic period after the opening of the southern Atlantic Ocean, which triggered the onset of subduction of the Nazca Plate. Volcanic arc- associated volcanism originally occurred within the Cordillera de la Costa in the Jurassic, but later it migrated resulting in the emplacement of the Tacaza and Toquepala groups and finally the Neogene Barroso group. The present-day volcanic arc is situated in the area of the Barroso group but has a narrower extent.

Off the coast of Peru, the Nazca Plate subducts at beneath the South America Plate, causing volcanism in three of the four volcanic belts in the Andes, including the Central Volcanic Zone where Tutupaca is located. Other Peruvian volcanoes include Sara Sara, Solimana, Coropuna, the Andagua volcanic field, AmpatoSabancaya, Chachani, Ubinas, Ticsani, Yucamane, and Casiri. During historical times, major eruptions took place in Peru at El Misti 2,000 years ago and at Huaynaputina in 1600, the latter of which claimed 1,500 fatalities and disrupted the climate of Earth. The basement of the region consists of folded Mesozoic sediments, and Cenozoic volcanic and sedimentary cover which overlies the Mesozoic rocks.

Due east of the Baja California Peninsula, the Rise is sometimes referred to as the Gulf of California Rift Zone. In this area, newly formed oceanic crust is intermingled with rifted continental crust originating from the North American Plate. Near Easter Island, the East Pacific Rise meets the Chile Rise at the Easter Island and Juan Fernandez microplates, trending off to the east where it subducts under the South American Plate at the Peru–Chile Trench along the coast of southern Chile. The southern extension of the East Pacific Rise (called the Pacific- Antarctic Ridge) merges with the Southeast Indian Ridge at the Macquarie Triple Junction south of New Zealand.

The volcanic zones are separated by areas where the subducting plate subducts at a flatter angle and volcanism is absent. The Peruvian flat slab between the Northern and the Central Volcanic Zones is associated with the subduction of the Nazca Ridge, the Pampean flat slab between the Central and the Southern Volcanic Zone is associated with the subduction of the Juan Fernandez Ridge, and the Patagonian volcanic gap between the Southern and the Austral Volcanic Zone is associated with the Chile Triple Junction. About 178 volcanoes are found in the Andes, 60 of which have been active in historical times. In addition, large calderas and monogenetic volcanoes exist in the Andes.

Igneous oceanic plateaus have a ratio intermediate between continental and oceanic crust, although they are more mafic than felsic. However, when a plate carrying oceanic crust subducts under a plate carrying an igneous oceanic plateau, the volcanism which erupts on the plateau as the oceanic crust heats up on its descent into the mantle erupts material which is more felsic than the material which makes up the plateau. This represents a step toward creating crust which is increasingly continental in character, being less dense and more buoyant. If an igneous oceanic plateau is subducted underneath another one, or under existing continental crust, the eruptions produced thereby produce material that is yet more felsic, and so on through geologic time.

Due to the flow in the lower mantle causing slab suction, changes in viscosity will have a much different effect than how it would apply to the upper mantle. In the lower mantle if you have a decrease in viscosity the flow will become much more rapid and increase the effect of slab suction and if viscosity in the lower mantle increases the effects of slab suction will decrease. Associated with the slab suction force is the idea of trench roll- back. As a slab of oceanic crust subducts into the mantle, the hinge of the plate (the point where the plate begins to subduct) tends to regress away from the trench.

There are three types of lithospheric plate boundaries: 1.) divergent (where lithosphere and oceanic crust is created at mid-ocean ridges), 2.) convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and 3.) transform (where two lithospheric plates slide past each other). An oceanic trench is a type of convergent boundary at which two oceanic lithospheric slabs meet; the older (and therefore denser) of these slabs flexes and subducts beneath the other slab. Oceanic lithosphere moves into trenches at a global rate of about a tenth of a square meter per second. Trenches are generally parallel to a volcanic island arc, and about 200 km from a volcanic arc.

Mariana Plate Boundary. 1 is West Mariana Ridge, 2 is Mariana Trough, 3 is Mariana Arc, 4 is Mariana Fore-Arc, 5 is Mariana Trench The tectonic plate is approximately 100 km thick and converging to the east at a rate of 50–80 mm/yr with the Pacific Plate subducting at 60–100 mm/yr This eastern subduction is divided into the Mariana Trench, which forms the southeastern boundary, and the Izu-Ogasawara Trench the northeastern boundary. The Izu-Ogasawara Trench and Mariana subduction zones are traveling at different rates. While the northern section of the Izu-Ogasawara Trench plate is subducting at 44 mm/yr, the southern section subducts at 14 mm/yr.

Bathymetry of the Kermadec volcanic island arc and surrounding areas The Kermadec scalyfin – part of the rich marine biota of the Kermadecs The islands are a volcanic island arc, formed at the convergent boundary where the Pacific Plate subducts under the Indo-Australian Plate. The subducting Pacific Plate created the Kermadec Trench, an 8 km deep submarine trench, to the east of the islands. The islands lie along the undersea Kermadec Ridge, which runs southwest from the islands towards the North Island of New Zealand and northeast towards Tonga (Kermadec-Tonga Arc). The four main islands are the peaks of volcanoes that rise high enough from the seabed to project above sea level.

Erimo Seamount lies southeast of Cape Erimo of Hokkaido, Japan. The seamount lies close to the intersection between the Kuril–Kamchatka Trench to the northeast and the Japan Trench to the south. Erimo Seamount lies oceanward and south and east from the trenches and it forms the northern tip of the Japan Trench; there the Pacific Plate subducts at a rate of , together with the seamounts on it such as Erimo which is currently entering the trench. Other seamounts in the area are Takuyo-Daiichi to the east-northeast and Ryofu-Daini to the east-southeast, and there is evidence of another seamount northwest of Erimo and in the process of being subducted.

The IBM arc system formed as a result of subduction of the western Pacific plate. The IBM arc system now subducts mid-Jurassic to Early Cretaceous lithosphere, with younger lithosphere in the north and older lithosphere in the south, including the oldest (~170 million years old, or Ma) oceanic crust. Subduction rates vary from ~2 cm (1 inch) per year in the south to 6 cm (~2.5 inches) in the north. The volcanic islands that comprise these island arcs are thought to have been formed from the release of volatiles (steam from trapped water, and other gases) being released from the subducted plate, as it reached sufficient depth for the temperature to cause release of these materials.

The Navarro River watershed contains the highly erodible Franciscan mélange (a jumbled matrix of rock types created as the Pacific tectonic plate subducts beneath the North American plate) and alluvial fill, as well as the Coastal Belt of the Franciscan Assemblage, which is more stable and resistant to erosion. Although serpentine outcrops, which are characteristic of this formation, are common locally, exposed serpentine has not been found on the Preserve. Alluvial fill occurs in Anderson Valley and low-lying areas of major tributaries, such as Rancheria Creek, and Franciscan melange is associated with middle and upper Rancheria Creek. Most of the rest of the watershed contains soil derived from the Coastal Belt of the Franciscan Assemblage.

Cross section of an oceanic trench formed along an oceanic-oceanic convergent boundary The Peru–Chile Trench is located just left of the sharp line between the blue deep ocean (on the left) and the light blue continental shelf, along the west coast of South America. It runs along an oceanic-continental boundary, where the oceanic Nazca Plate subducts beneath the continental South American Plate Trenches are centerpieces of the distinctive physiography of a convergent plate margin. Transects across trenches yield asymmetric profiles, with relatively gentle (~5°) outer (seaward) slopes and a steeper (~10–16°) inner (landward) slopes. This asymmetry is due to the fact that the outer slope is defined by the top of the downgoing plate, which must bend as it starts its descent.

On a broad scale, the tectonics of southern and central Pakistan reflect a complex plate boundary where the India plate slides northward relative to the Eurasia plate in the east, and the Arabia plate subducts northward beneath the Eurasia plate in the Makran (western Pakistan). These motions typically result in north–south to northeast–southwest strike-slip motion at the latitude of the 24 September earthquake that is primarily accommodated on the Chaman Fault, with the earthquake potentially occurring on one of the southernmost strands of this fault system. Further, more in-depth studies will be required to identify the precise fault associated with this event. Although seismically active, this portion of the Eurasia plate boundary region has not experienced large damaging earthquakes in recent history.

Fjords around Telegraph Island Telegraph Island is situated in a fjord at the northern end of the Musandam Peninsula, which forms part of the Oman mountain range described by the geologist George Martin Lees as "projecting like a spur into the vitals of Persia" (today's Iran). Being part of the edge of the Arabian tectonic plate, the rock stata are subjected to massive pressure as the plate subducts beneath the Eurasian plate. The result is that Musandam is being pushed downwards at approximately per year at its northernmost point, with spectacular results. Fresh-water springs that once flowed over the land may have become submerged, possibly giving rise to stories of sailors diving into the sea to collect fresh water in leather bags.

Map of the Nazca Plate and adjacent regional blocks of South America Off the western coast of South America, the Nazca Plate subducts beneath the South American Plate at a rate of in the Peru-Chile Trench. This subduction process is responsible for the formation of the Andes and the Altiplano-Puna plateau within the last 25 million years, as well as for volcanism and earthquakes. The magma erupted by the volcanoes is formed by the partial melting of the mantle after fluids originating in the downgoing slab have altered the mantle; the magmas often undergo fractional crystallization and absorb crustal material. Southern Peru has been affected by volcanic activity since the Ordovician and the Permian-Jurassic period, subduction- related volcanism becoming important from the Cretaceous onwards.

The associated trenches are formed as the oldest (most western) part of the Pacific plate crust increases in density with age, and because of this process finally reaches its lowest point just as it subducts under the crust to the west of it. The IBM arc system is an excellent example of an intra-oceanic convergent margin (IOCM). IOCMs are built on oceanic crust and contrast fundamentally with island arcs built on continental crust, such as Japan or the Andes. Because IOCM crust is thinner, denser, and more refractory than that beneath Andean-type margins, study of IOCM melts and fluids allows more confident assessment of mantle-to-crust fluxes and processes than is possible for Andean-type convergent margins.

The magma that forms them arises when water, which is trapped both in hydrated minerals and in the porous basalt rock of the upper oceanic crust, is released into mantle rock of the asthenosphere above the sinking oceanic slab. The release of water from hydrated minerals is termed "dewatering", and occurs at specific pressure/temperature conditions for specific minerals as the plate subducts to lower depths. The water freed from the subducting slab lowers the melting point of the overlying mantle rock, which then undergoes partial melting and rises due to its density relative to the surrounding mantle rock, and pools temporarily at the base of the lithosphere. The magma then rises through the crust, incorporating silica rich crustal rock, leading to a final intermediate composition.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of ; this process is responsible for the volcanism in the Ecuadorian Andes as well as mountain formation and earthquakes. The subduction process is further impacted by the entrainment of the Carnegie Ridge into the trench, which is suspected to have influenced volcanism in Ecuador by leading to the formation of adakitic melts, a notion that is however controversial. The Ecuadorian Andes consist of the Western Cordillera and the Eastern Cordillera with the Inter-Andean Valley between the two. The crust in the Ecuadorian Andes has been influenced both by changes in the tectonic stress regime and the integration of basaltic crustal fragments.

Map of the volcanic zones arcs in the Andes, and subducted structures affecting volcanism Off the southernmost west coast of South America, the Antarctic Plate subducts beneath the South American Plate at a rate of . This subduction process is responsible for volcanism in the Austral Volcanic Zone. The Austral Volcanic Zone is one of four volcanic zones in the Andes, the other three are the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone, all of which are separated from the Austral Volcanic Zone and each other by gaps where no volcanic activity occurs. Unlike the Austral Volcanic Zone, volcanism in these other zones is controlled by the subduction of the Nazca Plate beneath the South American Plate.

It is proposed that the Philippine Trench and PFZ represent a ‘shear partitioning’ mechanism, where the oblique physical motions of subduction at the convergent zone resulted in the development of the major strike-slip fault. In the Philippine Sea, the oblique motion of the subducting Philippine Sea Plate resulted in the formation of the Philippine trench and the PFZ back arc fault system. The oblique motion is accommodated by two vector components; one vector perpendicular to the converging Philippine Trench and one vector parallel to the PFZ. Approximately 30% of the oblique motion is accommodated by the PFZ while the remaining proportions are displaced along other regional tectonic features as the Philippine Sea Plate currently subducts below the Philippine archipelago at a rate of 6–8 cm/year.

The western side, the plate is bounded by the Okhotsk Plate at the Kuril-Kamchatka Trench and the Japan Trench, forms a convergent boundary by subducting under the Philippine Sea Plate creating the Mariana Trench, has a transform boundary with the Caroline Plate, and has a collision boundary with the North Bismarck Plate. In the south-west, the Pacific Plate has a complex but generally convergent boundary with the Indo-Australian Plate, subducting under it north of New Zealand forming the Tonga Trench and the Kermadec Trench. The Alpine Fault marks a transform boundary between the two plates, and further south the Indo-Australian Plate subducts under the Pacific Plate forming the Puysegur Trench. The southern part of Zealandia, which is to the east of this boundary, is the plate's largest block of continental crust.

Together with the neighbouring Laguna Amarga caldera and Laguna Escondida caldera Wheelwright forms an alignment of Miocene-Pliocene calderas; the latter caldera in part overlaps with the Wheelwright caldera. The region coincides with a lineament of volcanoes which forms the southern margin of the volcanically active Central Andes; south of this margin the Nazca Plate subducts beneath the South America Plate at a shallow angle and Quaternary volcanism is absent. The oldest outcrops are found in the Cordillera Claudio Gay mountain range just west of Wheelwright; these outcrops are Paleozoic sediments and volcanic rocks. Volcanic arc volcanism has been ongoing in the region since 180 million years ago and migrated eastward during that time, but the modern arc developed 26 million years ago when the Farallon Plate broke up.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate. This subduction is responsible for the volcanism in the volcanic arc, but the presence of the Carnegie Ridge on the subducting plate may modify the extent of volcanism: Whereas the volcanic arc in Colombia is relatively narrow, in Ecuador it is over wide. Pilavo lies west of the main volcanic arc and is constructed on a crust that is in part derived from the Caribbean large igneous province, part of which were integrated on the Ecuadorean coast and gave the crust thus a mafic signature. Otherwise, the basement includes Cretaceous marine and volcanic sequences, and is cut by a number of faults which controlled the location of the volcanic vents including these of Pilavo.

Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about ; this subduction is responsible for volcanic activity in the Central Volcanic Zone and elsewhere in the Andes. Volcanism does not occur along the entire length of the subduction zone; north of 15° and south of 28° the subducting plate moves downward at a shallower angle and this is associated with the absence of volcanic activity. Other volcanic zones exist in the Andes, including the Northern Volcanic Zone in Colombia and Ecuador and the Southern Volcanic Zone also in Chile. A furtherourth volcanic zone, the Austral Volcanic Zone, is caused by the subduction of the Antarctic Plate beneath the South America Plate and lies south of the Southern Volcanic Zone.

Since then, geologists have applied this model to other regions such as the Solonker Suture Zone of the Central Asian Orogenic belt, the Jiangnan Orogen, the Lhasa–Qiangtang collision zone and the Baker terrane boundary. Active examples of this system are 1) the Molucca Sea Collision Zone in Indonesia, in which the Molucca Sea plate subducts below the Eurasian plate and the Philippine Sea plate on two sides, and 2) the Adria microplate in the Central Mediterranean, subducting both on its western side (beneath the Apennines and Calabria) and on its eastern side (beneath the Dinarides). Note that the term "divergent" is used to describe one oceanic plate subducting in different directions on two opposite sides. It should not be confused with use of the same term in 'divergent plate boundary' which refers to a spreading center that separates two plates moving away from each other.

The Nazca Plate and Antarctic Plate subduct beneath the South America Plate in the Peru-Chile Trench at a pace of and , respectively, resulting in volcanic activity and geothermal manifestations in the Andes. Present-day volcanism occurs within four discrete belts: the NVZ (between 2°N–5°S), the CVZ (16°S–28°S), the SVZ (33°S–46°S) and the Austral Volcanic Zone (AVZ) (49°S-55°S). Between them they contain about 60 active volcanoes and 118 volcanoes which appear to have been active during the Holocene, not including potentially active very large silicic volcanic systems or very small monogenetic ones. These belts of active volcanism occur where the Nazca Plate subducts beneath the South America Plate at a steep angle, while in the volcanically inactive gaps between them the subduction is much shallower; thus there is no asthenosphere between the slab of the subducting plate and the overriding plate in the gaps.