T391 Tectonics, Geohazards, and Morphodynamics from High-Resolution Topography and Imagery (Posters)

Wednesday, 25 October 2017
9:00 AM - 6:30 PM
Halls 4EF

GEOTECTONIC EVOLUTION AND SEISMOTECTONICS OF NORTH FAULTS OF ALGECIRAS FAULT SYSTEM, COLOMBIA

Paper number: T391-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

The Eastern cordillera of Colombia was originated by the rapid upwelling of Mesozoic and Cenozoic rocks which began 8 millions years ago as a result of the tectonic inversion that occurred in normal faults that originated during the evolution of a Late Triassic basin that appeared when the Pangea supercontinent broke. The thickness of the sediments that constitute in its evolution is basin is 8 km. During Cenozoic the northwestern South America suffered two compresive tectonic (orogenic) phases. The first phase it was due to the final adjust (amalgamation) of Caribbean plate to Northwestern margin of South America during Campanian- Late Eocene lapse and, the second phase that began in Late Oligocene, is due to the adjustment of the subduction under northwest of South America of the Nazca Plate.

The Algeciras Fault System (AFS) is part of the Eastern Frontal Fault System. For the AFS with the help of the historical seismic intensity evaluation and instrumental historical seismicity record (1967 earthquake) have been assigned the 1785, 1827, 1917 and, 1967 historical earthquakes. These earthquakes were felt in Bogota and several Colombian cities located towards the center and southwest of the country. The Guayuriba Fault is reverse with 142,3 km of cumulative length is part of the AFS and corresponds to the northern fault of the fault system. Towards the west of the región where the Guayuriba Fault crosses, there are two semi - parallel reverse faults which are Altamira, and Nazareth.

In this región ocurred recently the earthquakes M = 5.4 and M= 5.0 of october 30, 2016, The earthquake M = 4.7 of december 16, 2016, and the earthquake M = 5.7 of february 6, 2017. The hypocentres of these earthquakes were located by the National Seismological Network of Colombia (RSNC). Also for this región with the historical seismic intensity evaluation have been asigned the historical earthquakes of july 12, 1785 and august 31, 1917.

The location of the epicenters verified here with field work, which are coincident with the location of the hypocenters given by RSNC makes estimate that the asperities are related with the interception in deep between Altamira and Nazareth faults with Guayuriba Fault. In the field work also checked tectonic geomorphology for faults scarps and several geomorphic expressions associated.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-302518

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