The Bucaramanga-Santa Marta Fault (BSMF, BSF) or Bucaramanga-Santa Marta Fault System (Spanish: (Sistema de) Falla(s) de Bucaramanga-Santa Marta) is a major oblique transpressional sinistral strike-slip fault (wrench fault) in the departments of Magdalena, Cesar, Norte de Santander and Santander in northern Colombia. The fault system is composed of two main outcropping segments, named Santa Marta and Bucaramanga Faults, and an intermediate Algarrobo Fault segment in the subsurface. The system has a total length of 674 kilometres (419 mi) and runs along an average north-northwest to south-southeast strike of 341 ± 23 from the Caribbean coast west of Santa Marta to the northern area of the Eastern Ranges of the Colombian Andes.

Quick Facts Etymology, Coordinates ...

Bucaramanga-Santa Marta Fault
Bucaramanga-Santa Marta Fault System (Sistema de) Falla(s) de Bucaramanga-Santa Marta
View of the Bucaramanga Fault along Bucaramanga
Location of the fault in Colombia Show map of Colombia Bucaramanga-Santa Marta Fault (Santander Department) Show map of Santander Department
Topographic map of northern Colombia showing the fault
Etymology	Bucaramanga, Santa Marta
Coordinates	7°05′25″N 73°05′15″W
Country	Colombia
Region	Caribbean, Andean
State	Magdalena, Cesar, Norte de Santander, Santander
Cities	Santa Marta, El Paso, Bucaramanga, Floridablanca, Piedecuesta
Characteristics
Elevation	1–1,500 m (3.3–4,921.3 ft)
Range	Sierra Nevada de Santa Marta Eastern Ranges  Andes
Part of	Andean faults
Segments	Santa Marta, Algarrobo, Bucaramanga Faults
Length	674 km (419 mi)
Strike	341 ± 23 (NNW-SSE)
Displacement	110 km (68 mi)
Tectonics
Plate	South American Plate
Status	Active
Earthquakes	Pre-Columbian era (~1020 AD)
Type	Strike-slip fault
Movement	Sinistral
Rock units	Caribbean, La Guajira, Tahamí & Chibcha Terranes
Age	Neogene-Holocene
Orogeny	Andean

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The fault system is a major bounding fault for various sedimentary basins and igneous and metamorphic complexes. The northern Santa Marta Fault segment separates the Sinú-San Jacinto Basin and Lower Magdalena Valley in the west from the Sierra Nevada de Santa Marta to the east. The buried Algarrobo Fault segment forms the boundary between the Lower Magdalena Valley and northern Middle Magdalena Valley to the west and the Cesar-Ranchería Basin in the east. The Bucaramanga Fault segment separates the middle part of the Middle Magdalena Valley in the west from the Santander Massif in the east.

The fault system bounds and cuts the four largest terranes of the North Andes Plate; the La Guajira, Caribbean and Tahamí Terranes along the Santa Marta section and intraterrane movement in the Andean Chibcha Terrane. Studies of the fault segments have shown the fault was active in the pre-Columbian era, around the year 1020, when the area around Bucaramanga was inhabited by the Guane. Various seismic events analysed to have occurred during the Holocene of the Bucaramanga Fault segment lead to the conclusion the fault is active.

The Bucaramanga-Santa Marta Fault is a major fault system which extends for a total distance of 674 kilometres (419 mi) from the Colombian Caribbean coast to the Eastern Ranges of the Colombian Andes to as far as about 6.5° N, south of the capital of Santander, Bucaramanga. The fault system, with an average strike of 341 ± 23 degrees, is a major wrench fault with a sinistral (left-lateral) displacement ranging from 45 to 110 kilometres (28 to 68 mi) and a fault slip rate of 0.01 to 0.2 millimetres (0.00039 to 0.00787 in) per year.^[1] The Santa Marta Fault forms the boundary between several distinct geological provinces: it is the western limit of the Santa Marta Massif with the Sinú-San Jacinto Basin, farther to the south the fault separates the Lower Magdalena Valley and northern Middle Magdalena Valley from the Cesar-Ranchería Basin. The Santander Massif is separated from the central part of the Middle Magdalena Valley along the southern Bucaramanga Fault segment of the fault system.^[2]

The fault divides the northern part of the Eastern Ranges in two structurally distinct regions. The Andean uplifted eastern block mainly comprises crystalline igneous and metamorphic rocks of Paleozoic and pre-Cambrian age, with lesser amounts of Jurassic, Triassic and Tertiary sedimentary rocks. In the western downthrown block, predominately sedimentary rocks of Quaternary and Tertiary age are found, with lesser amounts of Cretaceous and Jurassic rocks. The northern half of the fault is partially covered by Quaternary deposits in the Cesar and Magdalena valleys.^[2]

Municipalities

More information Municipality bold is capital, Department ...

Municipality bold is capital	Department	Altitude of urban centre	Inhabitants 2015	Notes
Santa Marta	Magdalena	0 m (0 ft)	466,000	[20][21]
Ciénaga	Magdalena	10 m (33 ft)	104,897	[22] [note 1]
Zona Bananera	Magdalena	30 m (98 ft)	60,524	[23]
Aracataca	Magdalena	40 m (130 ft)	39,473	[24]
Fundación	Magdalena	10 m (33 ft)	57,344	[25]
Algarrobo	Magdalena	24 m (79 ft)	12,576	[26]
El Copey	Cesar	180 m (590 ft)	27,212	[27]
Bosconia	Cesar	200 m (660 ft)	37,248	[28]
El Paso	Cesar	36 m (118 ft)	22,832	[29]
Chiriguaná	Cesar	40 m (130 ft)	19,650	[30]
Curumaní	Cesar	112 m (367 ft)	24,367	[31]
Chimichagua	Cesar	49 m (161 ft)	30,658	[32]
Pailitas	Cesar	77 m (253 ft)	17,166	[33]
Pelaya	Cesar	50 m (160 ft)	17,910	[34]
La Gloria	Cesar	50 m (160 ft)	12,938	[35]
El Carmen	Norte de Santander	761 m (2,497 ft)	14,005	[36]
Teorama	Norte de Santander	72 m (236 ft)	21,524	[37]
González	Cesar	1,240 m (4,070 ft)	6990	[38]
Ocaña	Norte de Santander	1,202 m (3,944 ft)	98,992	[39] [note 2]
San Martín	Cesar	119 m (390 ft)	18,548	[40]
San Alberto	Cesar	125 m (410 ft)	24,653	[41]
Ábrego	Norte de Santander	1,398 m (4,587 ft)	38,627	[42]
La Esperanza	Norte de Santander	1,566 m (5,138 ft)	12,012	[43]
Cáchira	Norte de Santander	2,025 m (6,644 ft)	10,970	[44]
El Playón	Santander	469 m (1,539 ft)	11,776	[45]
Rionegro	Santander	590 m (1,940 ft)	27,114	[46]
Bucaramanga	Santander	959 m (3,146 ft)	528,575	[47] [note 1]
Floridablanca	Santander	925 m (3,035 ft)	266,669	[48] [note 1]
Piedecuesta	Santander	1,005 m (3,297 ft)	156,167	[49] [note 1]
Cepitá	Santander	660 m (2,170 ft)	1865	[50]
San Andrés	Santander	1,777 m (5,830 ft)	8540	[51]

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The Bucaramanga-Santa Marta Fault system is located in northwestern South America, on the North Andes Plate, where the 20 ± 2 millimetres (0.787 ± 0.079 in)/yr east to southeastward moving Caribbean,^[52] 60 mm (2.4 in)/yr eastward subducting Malpelo,^[53] and South American Plates converge. Since Early Mesozoic times, the western portion of Colombia was subjected to different episodes of subduction, accretion and collision, at the boundaries of the South America continental and the oceanic Farallon, Nazca, and Caribbean Plates and various island arcs.^[54] The interaction of the plate tectonic movements formed the Northern Andean Block, separated from the Maracaibo Block by the Bucaramanga-Santa Marta Fault.^[55] The Northern Andean Block is subdivided into tectonic realms, with the Bucaramanga-Santa Marta Fault separating the Central Continental Sub-plate Realm in the west from the Maracaibo Sub-plate Realm in the east.^[56] It has been suggested that these two realms are dominated by respectively Nazca and Caribbean Plate subduction.^[57] The compressional stress regime caused the formation of the oblique sinistral Bucaramanga-Santa Marta Fault and dextral Oca and Boconó Faults.^[58]

The interplay between the Santa Marta and Oca Faults produced offshore Caribbean platforms and valleys north of the Sierra Nevada de Santa Marta near Taganga.^[59] Uplift along the western margin of the Santa Marta Fault probably commenced in the Pliocene.^[60]

The Bucaramanga Fault intersects with the Boconó Fault at the Santander Massif.^[61] In this area, the top of the subducting slab has been estimated at an initial depth of approximately 100 kilometres (62 mi), then a horizontal part for about 50 kilometres (31 mi), and a farther descending section to reach a depth of around 200 kilometres (120 mi). The slab section, called Bucaramanga slab, here has a dip that continues to the oceanic crust of the Caribbean seafloor. Towards the north of the Bucaramanga Nest or Swarm, in a north–south area approximately 200 kilometres (120 mi) in length, a well-defined Wadati-Benioff Zone extending to 175 kilometres (109 mi) depth has been identified.^[62]

A study published in 2009 about the Bucaramanga segment of the fault system revealed that the fault had eight episodes of activity during the late Holocene.^[63] The most recent activity has been inferred to have been around the year 1020.^[64] During this pre-Columbian era, the area around Bucaramanga was inhabited by the indigenous Guane. The authors consider the Bucaramanga Fault therefore as active.^[63]

Other faults in the seismically active zone, named Bucaramanga Nest, produced 27 earthquakes of magnitudes 4.0 to 5.3 between May 2012 and January 2013.^[65]