Seismogenic characterization of active faults in Colombia for seismic hazard assessment of the city of Bogotá: Formal agreement between the Colombian Geological Survey and the Centro Nacional Instituto Geológico y Minero de España (CSIC)

1st Scientific-Technical Conference of the Geological and Mining Institute of Spain-National Center (IGME, CSIC) 135 Seismogenic characterization of active faults in Colombia for seismic hazard assessment of the city of Bogotá: Formal agreement between the Colombian Geological Survey and the Centro Nacional Instituto Geológico y Minero de España (CSIC) J. García-Mayordomo1,*, R. Martín-Banda2, J. García-Senz1, M.T. López-Bahut1, M. López1, D. Robayo3 and M. Arcila3 1IGME, CSIC. Madrid, Spain 2IGME, CSIC. Oficina de Proyectos Sevilla, Spain 3SGC, Bogotá, Colombia *Corresp. Autor. C/Calera 1, 28760 Tres Cantos, Madrid, Spain. julian.g[email protected] Abstract The recent update of the Colombian seismic hazard model by Dirección de Geoamenzas of the Colombian Geological Survey (CGS), has identified the necessity of considering fault geological data in future successive updates of the hazard map. At the same time, the faultbased seismic hazard studies developed in the Centro Nacional IGME-CSIC have also identified the need of increasing the available knowledge on recent activity and paleoseismology of Spanish active faults in preparation for a future update of the national seismic hazard. In this frame, both CGS and IGME-CSIC, have formally agreed to collaborate in active faults research as well as their modelling for seismic hazard calculations to improve seismic risk provisions. It has been program firstly a pilot study in the transfer zone between the Algeciras and Guaicaramo faults (Colombia) that could also serve to provide the methodological framework for studying other faults in the country. The Algeciras fault is a dextral strike-slip structure running through the Western Colombian Cordillera along for more than 250 km from Ecuador’s border to approximately Mesetas (Meta, Colombia), where it finishes and presumably the Guaicaramo thrust system takes over controlling the cordillera mountain front and the pass to the Amazonía, a strip of land known as Borde Llanero. In this area, moderate to large magnitude earthquakes (Mw 5.0-7.0) have taken place and felt strong in the city of Bogotá (e.g., 1785, 1917, 1967, 2016). This formal agreement aims at obtaining, eventually, a seismogenic model of the transfer zone from geological and geophysical data for its incorporation in a new seismic hazard assessment of the city of Bogotá. The agreement has a duration of 2 years, and could be further extended by mutual agreement of both parties. Working plan consists in three main phases, basically: office work, field work, and fault geomodelling. Personnel from both institutions participate in all phases of the project. Currently, phases 1 and 2 are taken place, the first field campaign have been already done in February 2022.