The Eastern Frontal Fault System ( es, Sistema de Fallas de la Falla Frontal de la Cordillera Oriental) is a megaregional system of
oblique and
thrust faults cross-cutting Colombia from
Ecuador in the south to
Venezuela in the north. The system from south to north covers ten out of 32
departments
Department may refer to:
* Departmentalization, division of a larger organization into parts with specific responsibility
Government and military
*Department (administrative division), a geographical and administrative division within a country, ...
of Colombia;
Nariño,
Putumayo,
Cauca,
Huila,
Caquetá,
Cundinamarca,
Meta
Meta (from the Greek μετά, '' meta'', meaning "after" or "beyond") is a prefix meaning "more comprehensive" or "transcending".
In modern nomenclature, ''meta''- can also serve as a prefix meaning self-referential, as a field of study or ende ...
,
Boyacá,
Casanare and
Arauca. The Eastern Frontal Fault System underlies and affects the capitals of Putumayo,
Mocoa, Caquetá,
Florencia, Meta,
Villavicencio and Casanare,
Yopal
Yopal () is a municipality and capital city of the department of Casanare in Colombia.
History
During the period of the Spanish colonization of the Americas, the land on which Yopal stands was occupied by the indigenous Achagua people. The ...
. The fault system has a total length of with a cumulative length of the faults of and runs along an average northeast to southwest
strike of 042.1 ± 19 bordering and crossing the
Eastern Ranges of the Colombian
Andes. The fault system forms the boundary between the
North Andes microplate and 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-A ...
.
Several segments of the fault system are
active, with major
earthquakes
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
occurring in historical times. The
1827 Timaná (M
w 7.7),
1834 Sibundoy (M
w 7.0),
1917 Sumapaz (M
w 7.3),
1967 Neiva (M
w 7.2),
1995 Tauramena (M
w 6.5) and
2008 El Calvario earthquake
The 2008 El Calvario earthquake occurred in central Colombia on 24 May and measured 5.9 on the moment magnitude scale. The earthquake occurred at 2:20:43 p.m. (19:20:43 UTC) at the epicenter (El Calvario, Meta). The depth was 35 km; it ...
s (M
w 5.6) are associated with movement of the fault system.
Etymology
The fault system is named after the
Eastern Ranges, forming the front with the
Llanos
The Llanos (Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, sav ...
and
Caguán-Putumayo Basins.
Description
The Eastern Frontal Fault System is one of the most
active and continuous fault systems in Colombia. Several names have been given to it according to where it has been studied along its length. Local common fault names or "sections" from north to south are the Guaicáramo, Yopal, San José, Servitá-Santa Maria, Guayuriba, Algeciras, Mocoa, Florencia and Afiladores Faults. Other less common names include the Pajarito, Colepato, Acacías, and Colonia Faults. The fault system is probably an extension of the
Boconó Fault
The Boconó Fault is a complex of geological faults located in the Eastern Ranges of northeastern Colombia and the Mérida Andes of northwestern Venezuela. The fault has a NE-SW orientation; it is a strike-slip fault and has a dextral relative ...
and associated faults of the
Mérida Andes
Mérida or Merida may refer to:
Places
*Mérida (state), one of the 23 states which make up Venezuela
*Mérida, Mérida, the capital city of the state of Mérida, Venezuela
* Merida, Leyte, Philippines, a municipality in the province of Leyte
* ...
in Venezuela and likely continues south as a dextral fault in the Republic of Ecuador. The Eastern Frontal Fault System is the main fault system bounding the
Andean Ranges in the west and the lowlands or ''Llanos Orientales'' plains in the east. This fault system extends all the way south to the
Jambali Graben in the
Gulf of Guayaquil in Ecuador. It is considered to be the actual
plate boundary of the South American Plate disconnecting it from the North Andes Block. The Eastern Frontal Fault System extends from near latitude 3°N, north into the Venezuelan Andes, close to
San Cristóbal at about latitude 7.5°N. The fault system developed from an initial set of parallel fractures (
strike joints) arising from
distension
Distension (spelled distention in many style regimens) generally refers to an enlargement, dilation, or ballooning effect. It may refer to:
* Abdominal distension, typically a symptom of an underlying disease or dysfunction in the body, rather th ...
al forces. These dipped westwards, forming the eastern border of a huge
Paleozoic to
Cretaceous sedimentary basin. Later in the
Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, 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 Mya. ...
, regional uplift and shortening of the crust gave rise to the Eastern Ranges of Colombia. The initial
normal faults reversed motion and became
thrust faults in the ''Borde Llanero''. The Guaicáramo Fault System deforms late Neogene deposits and is characterised by neotectonic morphology that is some of the most outstanding and continuous in the country.
Segments
The fault system is subdivided into multiple segments.
Guaicáramo Fault System
The Guaicáramo Fault System is composed of three sections of faults, the northern Guaicáramo section of , the central Guaicáramo section of , and the southern Guaicáramo section of .
Yopal Fault
The long Yopal Fault is the easternmost active geologic
thrust fault known in northeastern Colombia. North of the city of
Yopal
Yopal () is a municipality and capital city of the department of Casanare in Colombia.
History
During the period of the Spanish colonization of the Americas, the land on which Yopal stands was occupied by the indigenous Achagua people. The ...
, it places
Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, 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 Mya. ...
rocks on the west against
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). It follows the Neogene Period and spans from 2.58 million years ...
alluvial deposits of the
Llanos Basin
The Llanos Basin ( es, Cuenca Llanos) or Eastern Llanos Basin ( es, Cuenca de los Llanos Orientales) is a major sedimentary basin of in northeastern Colombia. The wikt:onshore, onshore foreland basin, foreland on Mesozoic rift basin covers the dep ...
on the east.
San Pedro-Cumaral Fault
The long San Pedro-Cumaral system is formed by the parallel San Pedro and Cumaral Faults. The faults form well defined
fault scarps on
Tertiary and
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). It follows the Neogene Period and spans from 2.58 million years ...
sedimentary rocks that form hilly landscapes,
upwarping and tilting of terraces, deflected streams, linear fault ridges, and narrowing of streams on the eastern sides of the faults.
Servitá-Santa María Fault
The long Servitá-Santa María Fault extends close to the east margin of the Eastern Colombian Ranges near the
Guaicáramo Fault, east of
Bogotá
Bogotá (, also , , ), officially Bogotá, Distrito Capital, abbreviated Bogotá, D.C., and formerly known as Santa Fe de Bogotá (; ) during the Spanish period and between 1991 and 2000, is the capital city of Colombia, and one of the larges ...
. The combined fault is grouped in a system because of their morphologic similarity, geometric characteristics and
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). It follows the Neogene Period and spans from 2.58 million years ...
activity and includes the Servitá Fault to the south and Santa María and San Pedro de Jagua Faults to the north. Thrusting of
Paleozoic rocks over younger formations is seen along faults of this group. The faults offset
Jurassic,
Cretaceous and
Tertiary strata and deform
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). It follows the Neogene Period and spans from 2.58 million years ...
strata.
Guayuriba Fault
The long Guayuriba Fault is located to the southeast the Servitá-Santa María section. It lies south of and close to the city of
Villavicencio, at the base of the eastern front of the Eastern Ranges, and extends along the change of slope between the uplifted range and the flat plains of the
Llanos Basin
The Llanos Basin ( es, Cuenca Llanos) or Eastern Llanos Basin ( es, Cuenca de los Llanos Orientales) is a major sedimentary basin of in northeastern Colombia. The wikt:onshore, onshore foreland basin, foreland on Mesozoic rift basin covers the dep ...
.
Algeciras Fault
The long Algeciras Fault crosses the southward narrowing Eastern Ranges at an oblique angle, with its southern extension following the western flank. The fault displaces
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
crystalline shield rocks and
Mesozoic granites. Neotectonic deformation is suggested by the formation of a narrow and long
pull-apart basin
In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend creates an area of cru ...
filled with
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). It follows the Neogene Period and spans from 2.58 million years ...
sediments. Younger faults cross the basin diagonally. The fault is part of a set of major strike-slip faults that farther north probably join the
Guayuriba Fault, which borders the Eastern Ranges to the northeast.
Garzón-Pitalito Fault
The long Garzón-Pitalito Fault extends along the western slope of the Eastern Ranges southeast from the city of
Neiva and crosses the upper part of the
Magdalena Valley. In the northern half, the fault places
Jurassic to
Triassic sedimentary rocks on the eastern side in contact with
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). It follows the Neogene Period and spans from 2.58 million years ...
alluvium and
colluvium on the western side. Along its southern half, the fault places Jurassic-Triassic rocks in contact with
Cretaceous rocks. The Garzón-Pitalito Fault strikes toward and merges with the
Algeciras Fault to the north. To the south, it passes the towns of
Garzón,
Altamira,
Timaná,
Pitalito
Pitalito is a Colombian town and municipality located to the south of the Department of Huila, Colombia over the Valley of the Rio Grande de la Magdalena, 188 km from Huila's capital, Neiva. It is referred to as "''The Valley of Laboyos''" ...
and
San Agustín. In Pitalito, it creates a
pull-apart basin
In geology, a basin is a region where subsidence generates accommodation space for the deposition of sediments. A pull-apart basin is a structural basin where two overlapping (en echelon) strike-slip faults or a fault bend creates an area of cru ...
. The fault appears to dextrally displace the Suaza Fault. The place of the offset is marked by a large shutter ridge near where the
Suaza River
Suaza () is a town and municipality in the Huila Department
Huila () is one of the departments of Colombia. It is located in the southwest of the country, and its capital is Neiva, Colombia, Neiva.
Demography and Ethnography
Huila is a de ...
was dammed by huge landslides as a result of the
earthquake of November 16, 1827.
Suaza Fault
The long Suaza Fault crosses the western slope of the Eastern Ranges, close to the
Upper Magdalena Valley. It puts
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
crystalline rocks on the east against
Jurassic and
Cretaceous sedimentary rocks on the west.
Mesozoic granites are also displaced by the fault. A broad and long valley along the fault is filled with
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). It follows the Neogene Period and spans from 2.58 million years ...
sediments. Near the town of
Suaza
Suaza () is a town and municipality in the Huila Department, Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as w ...
, exposures show at least two episodes of neotectonic deformation: 1) early thrusting of Jurassic rocks over older Quaternary deposits, and 2) later deformation affecting the Jurassic rocks, old Quaternary deposits, and the relatively young Quaternary sediments. Most of the fault trace south of the Upper Magdalena valley is poorly located and documented. On the basis of regional correlations, it is believed that the Garzon-Pitalito Fault, the Suaza Fault, and the Algeciras Fault all are continuous southward extensions of the Guaicáramo Fault sections.
Mocoa Fault
The long Mocoa Fault strikes close to the base of the eastern side of the mountain front of the central mountains and coincides with the abrupt change in slope between the Andean Range on the west and the dense forest-covered hilly lowlands on the east. The fault places
Cretaceous and
Jurassic sedimentary rocks and
Tertiary to
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). It follows the Neogene Period and spans from 2.58 million years ...
volcanics
Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...
on the west against
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
crystalline rocks on the east.
Sibundoy Fault
The long Sibundoy Fault is located in the "Cordillera Centro-Oriental" to the east of the city of
Pasto, which is south of where the cordillera splits in two ranges (Eastern and Central Ranges), this location is known as
Colombian Massif
The Colombian Massif (from the Spanish Macizo Colombiano), also known colloquially as ''Nudo de Almaguer'', refers to a group of mountains within the Andes of south central Colombia. The massif is mainly within the area of the Cauca, Huila, and ...
. The Sibundoy Fault is probably the southward extension of the Suaza Fault and may well be part of the Afiladores Fault to the south. At the Sibundoy Valley (the locality where the Sibundoy Fault is best studied), the fault displaces
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
,
Jurassic and
Cretaceous rocks, and deforms
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). It follows the Neogene Period and spans from 2.58 million years ...
topographic features.
Afiladores Fault
The long Afiladores Fault runs through a geographic area of the Andes where the
Central
Central is an adjective usually referring to being in the center of some place or (mathematical) object.
Central may also refer to:
Directions and generalised locations
* Central Africa, a region in the centre of Africa continent, also known as ...
and Eastern Ranges merge into a single range known as the "Cordillera Centro-Oriental de Colombia". The fault offsets
Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
gneisses and
schists,
metamorphic Paleozoic rocks,
Mesozoic granitic rocks
A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quart ...
, and
Tertiary sedimentary deposits. The fault extends south into the Republic of Ecuador and probably connects with the
Chingual Fault.
Activity
Several segments of the fault system are active, with major earthquakes occurring in historical times. The
1827 Timaná (Mw 7.7),
1834 Sibundoy (Mw 7.0),
1917 Sumapaz (Mw 7.3),
1967 Neiva (Mw 7.2),
1995 Tauramena (Mw 6.5) and
2008 El Calvario earthquake
The 2008 El Calvario earthquake occurred in central Colombia on 24 May and measured 5.9 on the moment magnitude scale. The earthquake occurred at 2:20:43 p.m. (19:20:43 UTC) at the epicenter (El Calvario, Meta). The depth was 35 km; it ...
s (Mw 5.6) are associated with movement of the fault system.
See also
*
List of earthquakes in Colombia
*
Bucaramanga-Santa Marta Fault
*
Romeral Fault System
The Romeral Fault System ( es, Sistema de Fallas (de) Romeral) is a megaregional system of major parallel and anastomosing faults in the Cordillera Central (Colombia), Central Ranges of the Colombian Andes and the Cauca Basin, Cauca, Amagá Basin, ...
References
Bibliography
*
Maps
*
Further reading
* On joints and faults:
**
**
{{Tectonism in Colombia
Seismic faults of Colombia
Thrust faults
Strike-slip faults
Active faults
Faults
Faults
Faults
Faults
Faults
Faults
Faults
Faults
Faults
Faults
Earthquakes in Colombia
Colombia–Ecuador border
Colombia–Venezuela border