Bucaramanga-Santa Marta Fault

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.

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
Bucaramanga-Santa Marta Fault (Santander Department)
Topographic map of northern Colombia showing the fault
EtymologyBucaramanga, Santa Marta
Coordinates7°05′25″N 73°05′15″W
CountryColombia
RegionCaribbean, Andean
StateMagdalena, Cesar, Norte de Santander, Santander
CitiesSanta Marta, El Paso, Bucaramanga, Floridablanca, Piedecuesta
Characteristics
Elevation1–1,500 m (3.3–4,921.3 ft)
RangeSierra Nevada de Santa Marta
Eastern Ranges
 Andes
Part ofAndean faults
SegmentsSanta Marta, Algarrobo, Bucaramanga Faults
Length674 km (419 mi)
Strike341 ± 23 (NNW-SSE)
Displacement110 km (68 mi)
Tectonics
PlateSouth American Plate
StatusActive
EarthquakesPre-Columbian era (~1020 AD)
TypeStrike-slip fault
MovementSinistral
Rock unitsCaribbean, La Guajira, Tahamí & Chibcha Terranes
AgeNeogene-Holocene
OrogenyAndean

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.

Description

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]

Segments

The fault is divided into three segments; the main Bucaramanga Fault segment in the south, the Algarrobo Fault in the central section,[3] and the main Santa Marta Fault segment in the northern part of the fault system.[4][5][6] Between the two main outcropping segments, the Algarrobo Fault is present in the subsurface, overlain by Quaternary sediments.[7][8][9][10][11] The urban centre of the major coal producing municipality El Paso, Cesar is located right above the fault.[9] The fault reappears at surface east of Tamalameque, Cesar, where it continues south-southeastward into the Eastern Ranges in the departments of Norte de Santander and Santander.[12][13][14][15][16][17] The fault can be traced until San Andrés, Santander.[18] The Bucaramanga Fault possibly continues as the compressional Boyacá and Soapaga Faults on the Altiplano Cundiboyacense.[19]

Municipalities
Topography of Magdalena
Topography of Cesar
Topography of Norte de Santander
Topography of Santander
Municipality
bold is capital		 Department Altitude
of urban centre		 Inhabitants
2015		 Notes
Santa MartaMagdalena
0 m (0 ft)
466,000
[20][21]
CiénagaMagdalena
10 m (33 ft)
104,897
[22]
[note 1]
Zona BananeraMagdalena
30 m (98 ft)
60,524
[23]
AracatacaMagdalena
40 m (130 ft)
39,473
[24]
FundaciónMagdalena
10 m (33 ft)
57,344
[25]
AlgarroboMagdalena
24 m (79 ft)
12,576
[26]
El CopeyCesar
180 m (590 ft)
27,212
[27]
BosconiaCesar
200 m (660 ft)
37,248
[28]
El PasoCesar
36 m (118 ft)
22,832
[29]
ChiriguanáCesar
40 m (130 ft)
19,650
[30]
CurumaníCesar
112 m (367 ft)
24,367
[31]
ChimichaguaCesar
49 m (161 ft)
30,658
[32]
PailitasCesar
77 m (253 ft)
17,166
[33]
PelayaCesar
50 m (160 ft)
17,910
[34]
La GloriaCesar
50 m (160 ft)
12,938
[35]
El CarmenNorte de Santander
761 m (2,497 ft)
14,005
[36]
TeoramaNorte de Santander
72 m (236 ft)
21,524
[37]
GonzálezCesar
1,240 m (4,070 ft)
6990
[38]
OcañaNorte de Santander
1,202 m (3,944 ft)
98,992
[39]
[note 2]
San MartínCesar
119 m (390 ft)
18,548
[40]
San AlbertoCesar
125 m (410 ft)
24,653
[41]
ÁbregoNorte de Santander
1,398 m (4,587 ft)
38,627
[42]
La EsperanzaNorte de Santander
1,566 m (5,138 ft)
12,012
[43]
CáchiraNorte de Santander
2,025 m (6,644 ft)
10,970
[44]
El PlayónSantander
469 m (1,539 ft)
11,776
[45]
RionegroSantander
590 m (1,940 ft)
27,114
[46]
BucaramangaSantander
959 m (3,146 ft)
528,575
[47]
[note 1]
FloridablancaSantander
925 m (3,035 ft)
266,669
[48]
[note 1]
PiedecuestaSantander
1,005 m (3,297 ft)
156,167
[49]
[note 1]
CepitáSantander
660 m (2,170 ft)
1865
[50]
San AndrésSantander
1,777 m (5,830 ft)
8540
[51]

Tectonic setting
The tectonic history of the Bucaramanga-Santa Marta Fault, separating the Northern Andean from the Maracaibo Block (shown together as ND), is influenced by the interaction of the Malpelo, South American and Caribbean Plates

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]

Activity
Map of seismic threats

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]

Panorama
View of the Bucaramanga section of the fault east of Floridablanca, Santander

See also

Notes and references

Notes
  1. 2017 population data
  2. 2016 population data

References
  1. Jiménez Díaz, 2013, p.56
  2. Paris et al., 2000, p.10
  3. Cuéllar et al., 2012, p.77
  4. Plancha 11, 1998
  5. Plancha 18, 1999
  6. Plancha 19, 2007
  7. Plancha 26, 2007
  8. Plancha 33, 2007
  9. Plancha 40, 2002
  10. Plancha 47, 2001
  11. Plancha 55, 2006
  12. Plancha 65, 1994
  13. Plancha 66, 2009
  14. Plancha 76, 1980
  15. Plancha 86, 1981
  16. Plancha 97, 1981
  17. Plancha 120, 1977
  18. Plancha 136, 1984
  19. Sánchez et al., 2012, p.3008
  20. DANE, 2015, p.29
  21. (in Spanish) Official website Santa Marta
  22. (in Spanish) Official website Ciénaga
  23. (in Spanish) Official website Zona Bananera
  24. (in Spanish) Official website Aracataca
  25. (in Spanish) Official website Fundación
  26. (in Spanish) Official website Algarrobo
  27. (in Spanish) Official website El Copey
  28. (in Spanish) Official website Bosconia
  29. (in Spanish) Official website El Paso, Cesar
  30. (in Spanish) Official website Chiriguaná
  31. (in Spanish) Official website Curumaní
  32. (in Spanish) Official website Chimichagua
  33. (in Spanish) Official website Pailitas
  34. (in Spanish) Official website Pelaya
  35. (in Spanish) Official website La Gloria, Cesar
  36. (in Spanish) Official website El Carmen
  37. (in Spanish) Official website Teorama
  38. (in Spanish) Official website González, Cesar
  39. (in Spanish) Official website Ocaña
  40. (in Spanish) Official website San Martín, Cesar
  41. (in Spanish) Official website San Alberto, Cesar
  42. (in Spanish) Official website Ábrego
  43. (in Spanish) Official website La Esperanza
  44. (in Spanish) Official website Cáchira
  45. (in Spanish) Official website El Playón
  46. (in Spanish) Official website Rionegro
  47. (in Spanish) Official website Bucaramanga
  48. (in Spanish) Official website Floridablanca
  49. (in Spanish) Official website Piedecuesta
  50. (in Spanish) Official website Cepitá
  51. (in Spanish) Official website San Andrés
  52. Egbue et al., 2014, p.9
  53. Colmenares & Zoback, 2003, p.721
  54. Nevistic et al., 2003, p.132
  55. Colmenares & Zoback, 2003, p.722
  56. Cediel et al., 2003, p.818
  57. Yarce et al., 2014, p.57
  58. Idárraga García et al., 2011, p.44
  59. Posada Posada et al., 2012, p.103
  60. Idárraga García et al., 2011, p.57
  61. Diederix et al., 2009, p.19
  62. Colmenares & Zoback, 2003, p.723
  63. Diederix et al., 2009, p.23
  64. Diederix et al., 2009, p.21
  65. Perico & Perico, 2014, p.6

Bibliography

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