The Lwandle Plate is one of three tectonic microplates, along with the Rovuma Plate and Victoria Plate, that make up the African Plate with the Somali Plate and the Nubian Plate. Its discovery is very recent, so the velocity of the plate is neither well known nor well understood. [1] Many experiments are ongoing to quantify this. [2] The Lwandle Plate lies between 30°E and 50°E, sharing a boundary with the Nubian, Somali, and Antarctic Plates. [3]
The Lwandle Plate is largely oceanic, lying off the southeast coast of Africa. It is currently believed that the southern part of Madagascar forms part of the Lwandlean Plate, with one of the plate boundaries cutting through the island. [3] [4] [5]
For many years it was widely accepted that rifting in the East African Rift system, 22–25 million years ago, resulted in the splitting of the African Plate into 2 smaller plates – the Somali Plate and the Nubian Plate. [7] However, most recently, through the application of GPS technology and integration of earthquake data, it was discovered that the rift created three additional “microplates” – the Lwandle Plate, Victoria Plate, and Rovuma Plate. [1]
Earthquakes occur most often at plate boundaries and have been used as a guide to predict the locations of multiple plate boundaries. [8] [9] “Lwandle’s” existence was postulated after studying earthquake data in areas that were once assumed to be the interiors of the Nubian and Somali plates. [10] By including the Lwandlean Plate in their calculation, researchers were able to more accurately solve for the intersection between the East African Rift and the Southwest Indian Ridge.
GPS technology and data was also introduced in an effort to show with certainty the difference between the Somali Plate and the Nubian Plate. Using the GPS data, researchers could measure the velocity of tectonic plates from their interiors. [11] [12] [13]
The existence of the Lwandle Plate was first quantified using the Lwandle-Antarctica-Nubia plate circuit closure constrained by spreading rates and transform azimuths along the Southwest Indian Ridge. Mathematical plate circuit closure is attained while including the existence of Lwandle; using plate circuit closure, plate velocities can be calculated from the velocities of other plates. [4] [14]
In 2008, the entire East African Rift System was successfully "quantified" through the integration of the GPS and earthquake data with the spreading rate and transform azimuth constraints. [5]
There have been very few studies that directly study the Lwandlean Plate. Previous studies about Lwandle have primarily been focused on attempting to quantify the mechanics of the African Rift System. [1] [5] For this reason, the presumed evolution and formation of the microplates are not well known.
Lwandle was assumed to be part of the Somali plate, at first. Here are two models that show how thinking about Lwandle has evolved.
Tectonic Model Excluding Lwandle Plate | Tectonic Model Including Lwandle Plate |
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In this model, Lwandle is considered to be part of the Somali Plate. ![]() | In this model, Lwandle is its own, separate plate. ![]() |
The majority of Lwandle's plate boundaries are not well understood. [5] What is known is:
GPS data paired with earthquake slip data is used to estimate the velocity of the Lwandle Plate and its neighbors. The velocity of the Lwandlean Plate, relative to the Nubian and Somali plates, is estimated to be a very slow rate (1–2 mm/yr). With these low rates of motion, it is expected that this area wouldn't have much seismic activity. The data supports this expectation. [1] Though Lwandle is moving faster relative to the Antarctic plate than to Nubian and Somali, this spreading ridge is one of the slowest on planet Earth, spreading at less than half the rate of human fingernail growth. [19] It appears that Lwandle will be in its current position for quite some time. [3]
Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
The African Plate, also known as the Nubian Plate, is a major tectonic plate that includes much of the continent of Africa and the adjacent oceanic crust to the west and south. It is bounded by the North American Plate and South American Plate to the west ; the Arabian Plate and Somali Plate to the east; the Eurasian Plate, Aegean Sea Plate and Anatolian Plate to the north; and the Antarctic Plate to the south.
The Australian Plate is a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately 100 million years ago when India broke away and began moving north. Australia and Antarctica had begun rifting by 96 million years ago and completely separated a while after this, some believing as recently as 45 million years ago ,but most accepting presently that this had occurred by 60 million years ago.
The Somali Plate is a minor tectonic plate which straddles the Equator in the Eastern Hemisphere. It is currently in the process of separating from the African Plate along the East African Rift Valley. It is approximately centered on the island of Madagascar and includes about half of the east coast of Africa, from the Gulf of Aden in the north through the East African Rift Valley. The southern boundary with the Nubian-African Plate is a diffuse plate boundary consisting of the Lwandle Plate.
The Jordan Rift Valley, also Jordan Valley(Hebrew: בִּקְעָת הַיַרְדֵּן Bīqʿāt haYardēn, Arabic: الغور Al-Ghor or Al-Ghawr), also called the Syro-African Depression, is an elongated depression located in modern-day Israel and Jordan. This geographic region includes the entire length of the Jordan River – from its sources, through the Hula Valley, the Korazim block, the Sea of Galilee, the (Lower) Jordan Valley, all the way to the Dead Sea, the lowest land elevation on Earth – and then continues through the Arabah depression, the Gulf of Aqaba whose shorelines it incorporates, until finally reaching the Red Sea proper at the Straits of Tiran.
The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a larger Great Rift Valley that extended north to Asia Minor.
A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most of them result from tensional forces, caused by a process known as oceanic trench rollback, where a subduction zone moves towards the subducting plate. Back-arc basins were initially an unexpected phenomenon in plate tectonics, as convergent boundaries were expected to universally be zones of compression. However, in 1970, Dan Karig published a model of back-arc basins consistent with plate tectonics.
Easter Plate is a tectonic microplate located to the west of Easter Island off the west coast of South America in the middle of the Pacific Ocean, bordering the Nazca Plate to the east and the Pacific Plate to the west. It was discovered from looking at earthquake distributions that were offset from the previously perceived Nazca-Pacific Divergent boundary. This young plate is 5.25 million years old and is considered a microplate because it is small with an area of approximately 160,000 square kilometres (62,000 sq mi). Seafloor spreading along the Easter microplate's borders have some of the highest global rates, ranging from 50 to 140 millimetres /yr.
The Afar Triple Junction is located along a divergent plate boundary dividing the Nubian, Somali, and Arabian plates. This area is considered a present-day example of continental rifting leading to seafloor spreading and producing an oceanic basin. Here, the Red Sea Rift meets the Aden Ridge and the East African Rift. The latter extends a total of 6,500 kilometers (4,000 mi) from the Afar Triangle to Mozambique.
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 Rodrigues Triple Junction (RTJ), also known as the Central Indian [Ocean] Triple Junction (CITJ) is a geologic triple junction in the southern Indian Ocean where three tectonic plates meet: the African Plate, the Indo-Australian Plate, and the Antarctic Plate. The triple junction is named for the island of Rodrigues which lies 1,000 km (620 mi) north-west of it.
The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean. A divergent tectonic plate boundary separating the Somali Plate to the north from the Antarctic Plate to the south, the SWIR is characterised by ultra-slow spreading rates (only exceeding those of the Gakkel Ridge in the Arctic) combined with a fast lengthening of its axis between the two flanking triple junctions, Rodrigues (20°30′S70°00′E) in the Indian Ocean and Bouvet (54°17′S1°5′W) in the Atlantic Ocean.
Slab pull is a geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate. In 1975 Forsyth and Uyeda used the inverse theory method to show that, of the many forces likely to be driving plate motion, slab pull was the strongest. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. This force and slab suction account for almost all of the force driving plate tectonics. The ridge push at rifts contributes only 5 to 10%.
The Great Rift Valley of Ethiopia, is a branch of the East African Rift that runs through Ethiopia in a southwest direction from the Afar Triple Junction. In the past, it was seen as part of a "Great Rift Valley" that ran from Mozambique to Syria.
The Rovuma Plate or Rovuma microplate is one of the four tectonic microplates that, together with the larger Nubian Plate, form the African Plate. The other three are the Somali Plate, the Lwandle Plate and the Victoria Plate.
The geology of Socotra is part of the national geology of Yemen. Ancient Precambrian metamorphic rocks are intruded by younger igneous rocks, overlain by limestones and other marine sediments that deposited during marine transgression periods in the Cretaceous and the past 66 million years of the Cenozoic. The island is on the Somali Plate, which rifted away from the Arabian mainland within the past 60 million years.
Éric Calais is a French geologist-geophysicist, born in 1964, internationally recognized practitioner of high-precision space geodesy and a pioneer in its applications to measure seismic deformations at the boundaries of tectonic plates and in their interiors. He has been a member of the French Academy of Sciences since 2017.
The Victoria Microplate or Victoria Plate is a small tectonic plate in East Africa. It is bounded on all sides by parts of the active East African Rift System. It is currently rotating anticlockwise. Its boundaries are close to those of the mainly Archaean Tanzania Craton, with the two arms of the rift system having propagated along the surrounding Proterozoic shear belts. To the northwest, west and southwest it has a boundary with the Nubian Plate, to the northeast and east with the Somali Plate and to the southeast with the Rovuma Plate.
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