Transform fault in the context of Geologic fault

The Adriatic or Apulian plate is a small tectonic plate carrying primarily continental crust that broke away from the African plate along a large transform fault in the Cretaceous period. The name Adriatic plate is usually used when referring to the northern part of the plate. This part of the plate was deformed during the Alpine orogeny, when the Adriatic/Apulian plate collided with the Eurasian plate.

The Adriatic/Apulian plate is thought to still move independently of the Eurasian plate in NNE direction with a small component of counter-clockwise rotation. The fault zone that separates the two is the Periadriatic Seam that runs through the Alps. Studies indicate that in addition to deforming, the Eurasian continental crust has actually subducted to some extent below the Adriatic/Apulian plate, an unusual circumstance in plate tectonics. Oceanic crust of the African plate is also subducting under the Adriatic/Apulian plate off the western and southern coasts of the Italian Peninsula, creating a berm of assorted debris which rises from the seafloor and continues onshore. This subduction is also responsible for the volcanic interactions of southern Italy.

A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes resulting from divergent tectonic activity are usually non-explosive whereas those resulting from convergent tectonic activity cause violent eruptions. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift, the Wells Gray-Clearwater volcanic field, and the Rio Grande rift in North America. Volcanism away from plate boundaries most likely arises from upwelling diapirs from the core–mantle boundary called mantle plumes, 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism or intraplate volcanism, in which the plume may cause thinning of the crust and result in a volcanic island chain due to the continuous movement of the tectonic plate, of which the Hawaiian hotspot is an example. Volcanoes are usually not created at transform tectonic boundaries where two tectonic plates slide past one another.

In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep.

A fault plane is the plane that represents the fracture surface of a fault. A fault trace or fault line is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geological maps to represent a fault.

The Cayman Trough (also known as the Cayman Trench, Bartlett Deep and Bartlett Trough) is a complex transform fault zone pull-apart basin which contains a small spreading ridge, the Mid-Cayman Rise, on the floor of the western Caribbean Sea between Jamaica and the Cayman Islands. It is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate. It extends from the Windward Passage, going south of the Sierra Maestra of Cuba toward Guatemala. The transform fault continues onshore as the Polochic-Motagua fault system, which consists of the Polochic and Motagua faults. This system continues on until the Chiapas massif where it is part of the diffuse triple junction of the North American, Caribbean and Cocos plates.

The relatively narrow trough trends east-northeast to west-southwest and has a maximum depth of 7,686 metres (25,217 ft). Within the trough is a slowly spreading north–south ridge which may be the result of an offset or gap of approximately 420 kilometres (260 mi) along the main fault trace. The Cayman spreading ridge shows a long-term opening rate of 11–12 mm/yr. The eastern section of the trough has been named the Gonâve Microplate. The Gonâve plate extends from the spreading ridge east to the island of Hispaniola. It is bounded on the north by the Oriente and Septentrional fault zones. On the south the Gonâve is bounded by the Walton fault zone, the Jamaica restraining bend and the Enriquillo-Plantain Garden fault zone. The two bounding strike slip fault zones are left lateral. The motion relative to the North American Plate is 11 mm/yr to the east and the motion relative to the Caribbean Plate is 8 mm/yr. The western section of the trough is bounded to its south by the Swan Islands Transform Fault.

The Puerto Rico Trench is located on the boundary between the North Atlantic Ocean and Caribbean Sea, parallel to and north of Puerto Rico, where the oceanic trench reaches the deepest points in the Atlantic Ocean. The trench is associated with a complex transition from the Lesser Antilles frontal subduction zone between the South American plate and Caribbean plate to the oblique subduction zone and the strike-slip transform fault zone between the North American plate and Caribbean plate, which extends from the Puerto Rico Trench at the Puerto Rico–Virgin Islands microplate through the Cayman Trough at the Gonâve microplate to the Middle America Trench at the Cocos plate.

Constituting the deepest points in the Atlantic Ocean, the trench is 810 kilometres (503 mi) long and has a maximum documented depth between 8,376 metres (27,480 ft) and 8,740 metres (28,675 ft). The deepest point is commonly referred to as the Milwaukee Deep, with the Brownson Deep naming the seabed surrounding it. However, more recently, the latter term has also been used interchangeably with the former to refer to this point. The exact point was identified by the DSSV Pressure Drop using a state-of-the-art Kongsberg EM124 multibeam sonar in 2018, and then directly visited and its depth verified by the crewed submersible Deep-Submergence Vehicle DSV Limiting Factor (a Triton 36000/2 model submersible) piloted by Victor Vescovo.

The Aden Ridge is a part of an active oblique rift system located in the Gulf of Aden, between Somalia and the Arabian Peninsula to the north. The rift system marks the divergent boundary between the Somali and Arabian tectonic plates, extending from the Owen transform fault in the Arabian Sea to the Afar triple junction or Afar Plume beneath the Gulf of Tadjoura in Djibouti.

The Gulf of Aden is divided east to west into three distinct regions by large-scale discontinuities, the Socotra, Alula Fartak, and Shukra-El Sheik transform faults. Located in the central region, bounded by the Alula Fartak fault and Shukra-El Sheik fault, is the Aden spreading ridge. The Aden Ridge connects to the Sheba Ridge in the eastern region and to the Tadjoura Ridge in the western region. Due to oblique nature of the Aden Ridge, it is highly segmented. Along the ridge there are seven transform faults that offset it to the north.

The Dead Sea Transform (DST) fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run for about 1,000 km from the Marash triple junction (a junction with the East Anatolian Fault in southeastern Turkey) to the northern end of the Red Sea Rift (just offshore of the southern tip of the Sinai Peninsula). The fault system forms the transform boundary between the African plate to the west and the Arabian plate to the east. It is a zone of left lateral (sinistral) displacement, signifying the relative motions of the two plates. Both plates are moving in a general north-northeast direction, but the Arabian plate is moving faster, resulting in the observed left lateral motions along the fault of approximately 107 km at its southern end. A component of extension is also present in the southern part of the transform, which has contributed to a series of depressions, or pull-apart basins, forming the Gulf of Aqaba, Dead Sea, Sea of Galilee, and Hula basins. A component of shortening affects the Lebanon restraining bend, leading to uplift on both sides of the Beqaa valley. There is local transtension in the northernmost part of the fault system, forming the Ghab pull-apart basin. The southern part of the fault system runs roughly along the political border of Lebanon and Israel on its western side, and southern Syria and Jordan on the eastern side.

Tectonic plate interactions are classified into three basic types:

• Convergent boundaries are areas where plates move toward each other and collide. These are also known as compressional or destructive boundaries.
  • Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction.
  • Orogenic belts occur where two continental plates collide and push upwards to form large mountain ranges. These are also known as collision boundaries.
  • Subduction zones occur where an oceanic plate meets a continental plate and is pushed underneath it. Subduction zones are marked by oceanic trenches. The descending end of the oceanic plate melts and creates pressure in the mantle, causing volcanoes to form.
    • Back-arc basins can form from extension in the overriding plate, in response to the displacement of the subducting slab at some oceanic trenches. This paradoxically results in divergence which was only incorporated in the theory of plate tectonics in 1970, but still results in net destruction when summed over major plate boundaries.
• Divergent boundaries are areas where plates move away from each other, forming either mid-ocean ridges or rift valleys. These are also known as constructive boundaries.
• Transform boundaries occur when two plates grind past each other with only limited convergent or divergent activity.

The Anatolian plate is a continental tectonic plate lying under Asiatic part of Turkey, known as Anatolia. Most of the country of Turkey is located on the Anatolian plate. The plate is separated from the Eurasian plate and the Arabian plate by the North Anatolian Fault and the East Anatolian Fault respectively. According to the American Museum of Natural History, the Anatolian transform fault system is "probably the most active in the world".

Most significant earthquakes in the region have historically occurred along the northern fault, such as the 1939 Erzincan earthquake. The northern edge is a transform boundary with the Eurasian plate, forming the North Anatolian Fault zone (NAFZ). The East Anatolian Fault, a left lateral transform fault, forms a boundary with the Arabian plate. The devastating 2023 Turkey–Syria earthquakes occurred along the active East Anatolian Fault at a strike-slip fault where the Arabian plate is sliding past the Anatolian plate horizontally.