The Ibagué Fault () is a major dextral slightly

oblique Oblique may refer to: * an alternative name for the character usually called a slash (punctuation) ( / ) *Oblique angle, in geometry * Oblique triangle, in geometry * Oblique lattice, in geometry * Oblique leaf base, a characteristic shape of the ...

strike-slip fault 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 ...

in the department of Tolima in central

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

. The fault has a total length of and runs along an average east-northeast to west-southwest

strike Strike may refer to: People *Strike (surname) * Hobart Huson, author of several drug related books Physical confrontation or removal *Strike (attack), attack with an inanimate object or a part of the human body intended to cause harm * Airstrike, ...

of 067.9 ± 11 cross-cutting the

Central Ranges Central Ranges (code CER) is an Australian bioregion, with an area of 101,640.44 square kilometres (39,244 sq mi) spreading across two states and one territory: South Australia, Western Australia, and the Northern Territory.Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...

. The fault is part of a regional shear zone and has been active in historical times, possibly associated with the 1825 Ibagué earthquake and an earthquake in 1942.

Etymology

The fault is named after

Ibagué Ibagué () (referred to as San Bonifacio de Ibagué del Valle de las Lanzas during the New Kingdom of Granada, Spanish period) is the capital of Tolima Department, Tolima, one of the 32 departments that make up the Republic of Colombia. The city ...

, the capital of Tolima.Diederix et al., 2006, p.492

Description

The Ibagué Fault crosses the central part and eastern slope of the

, close to the city of Ibagué. The fault strikes west-southwest to east-northeast, controlling the course of the Cocora River. The fault has a well developed fault trace with prominent linear fault ridges (whale backs) as much as long and high, fault scarplets aligned with ridges, sag ponds, fault-controlled drainage, tilted deposits and upwarping. There is about of (young) displacement along strike as calculated from a "whale back" offset by the fault.Paris et al., 2000, p.50 The fault, forming a series of ramps,Cuéllar Cárdenas, 2014, p.43 terminates at the

Magdalena River The Magdalena River (, ; less commonly ) is the main river of Colombia, flowing northward about through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of its lower reaches, ...

, north of

Guataquí Guataquí is a municipality and town of Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bo ...

.Plancha 245, 1999

Tectonic framework

The Ibagué Fault forms part, with the Garrapatas and Cucuana faults, of a shear zone between the latitudes 4 and 5 degrees north. To the north of this zone, regional structures are oriented along a north-northeast strike, characterised by sinistral displacement, among others the San Jerónimo, Silvia–Pijao, Cauca–Almaguer,

Murindó Murindó is a Colombian municipality located in the subregion of Urabá in the department of Antioquia. It borders the department of Chocó to the north, the municipalities of Dabeiba and Frontino to the east, the municipality of Vigía del F ...

, Bituima–La Salina and Bucaramanga–Santa Marta faults. The movement along these structures generates a transpressive tectonic regime, related to the collision of the Chocó Block in the west of Colombia, during the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

. To the south of the structural zone the Ibagué Fault belongs to, north-northeast striking faults are mostly dextral, such as the Buesaco–Aranda, Cali–Patía, and

Algeciras Algeciras () is a city and a municipalities in Spain, municipality of Spain belonging to the province of Cádiz, Andalusia. Located in the southern end of the Iberian Peninsula, near the Strait of Gibraltar, it is the largest city on the Bay of G ...

faults. Those are produced by the oblique

subduction Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second p ...

of the

Malpelo plate The Malpelo plate is a small tectonic plate (microplate) located off the coasts west of Ecuador and Colombia. It is the 57th plate to be identified. It is named after Malpelo Island, the only emerged part of the plate. It is bounded on the west ...

, formerly considered belonging to the

Nazca plate The Nazca plate or Nasca plate, named after the Nazca region of southern Peru, is an oceanic list of tectonic plates, tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru– ...

with the continental margin of the

South American plate The South American plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African plate, with which it forms the southern part of the Mid ...

.Montes et al., 2004, p.14 The Ibagué Fault cross-cuts the central part of the Central Ranges and extends along a strike of approximately 070 to the east to the

Middle Magdalena Valley The Middle Magdalena Valley, Middle Magdalena Basin or Middle Magdalena Valley Basin (, commonly abbreviated to VMM) is an intermontane basin, located in north-central Colombia between the Central and Eastern Ranges of the Andes. The basin, cove ...

. Along its trace it principally cuts

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, caus ...

s of the Cajamarca Complex, the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

age Ibagué Batholith consisting of

granodiorite Granodiorite ( ) is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. The term banatite is sometimes used informally for various rocks ranging from gra ...

tonalite Tonalite is an igneous rock, igneous, plutonic (Intrusive rock, intrusive) rock (geology), rock, of felsic composition, with phaneritic (coarse-grained) texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with alkali fe ...

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

s, porphyrics of

andesitic Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

and

dacitic Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

composition and extrusive rocks as pyroclastic deposits and lava,Cuéllar Cárdenas et al., 2014, p.39

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

and

Neogene The Neogene ( ,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period million years ago. It is the second period of th ...

sedimentary rocks of the Gualanday and Honda Groups and displacing and deforming the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

Ibagué Fan (), which is of volcano-sedimentary origin.Montes et al., 2004, p.15 The fault passes southeast of the

Nevado del Ruiz Nevado del Ruiz (), also known as La Mesa de Herveo () is a volcano on the border of the departments of Caldas and Tolima in Colombia, being the highest point of both. It is located about west of the capital city Bogotá. It is a stratovolca ...

and

Cerro Machín Cerro Machín is a stratovolcano located in Tolima Department, Colombia. Cerro Machin is a volcanic plug that is approximately the same age (1,000,000+ years) as the Ruiz-Tolima Massif and has the appearance of being part of that volcanic system. ...

volcanoes 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 fo ...

.Montes et al., 2004, p.16Montes et al., 2004, p.17

Activity

A rate of per year is estimated and per year published,Diederix et al., 2006, p.502 based on deformed and offset Quaternary features and dated deposits. A calculated

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

of 7.0-7.2 is based on most probable fault rupture length of about , from Ibagué to Piedras. The most recent movement is estimated at 1040 to 1280 AD on the basis of

radiocarbon dated Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was de ...

deposits.Montes et al., 2004, p.167 Two epicentres of historical earthquakes are located close to the fault, an earthquake of May 22, 1942 with magnitude 5.8 and an

intensity Intensity may refer to: In colloquial use * Strength (disambiguation) *Amplitude * Level (disambiguation) * Magnitude (disambiguation) In physical sciences Physics *Intensity (physics), power per unit area (W/m2) *Field strength of electric, m ...

in Ibagué of VIII and the intensity VI

1825 Ibagué earthquake Eighteen or 18 may refer to: * 18 (number) * One of the years 18 BC, AD 18, 1918, 2018 Film, television and entertainment * ''18'' (film), a 1993 Taiwanese experimental film based on the short story ''God's Dice'' * ''Eighteen'' (film), a 20 ...

of January 1, 1825.Montes et al., 2004, p.18

References

Bibliography

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Maps

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