Research Topic 2 (RT2): Building a harmonised database of ‘hazardous’ crustal faults

The location in space and time, as well as the prehistoric displacement record of seismogenically capable geologic structures, constitute basic insights for seismic hazard assessment (SHA). This is particularly relevant for areas where the recurrence interval of destructive earthquakes is larger than the time coverage provided by the seismic catalog. Destructive earthquakes onshore South America occur along faults and many important cities and capital towns are settled nearby faults whose seismogenic capability is known or suspected. However, many seismic hazard assessments in South America do not consider potentially seismogenic structures at all, or do so only sparingly, in some cases because the required fault data are absent or not available in an adequate format for engineers or SHA requirements. Existing databases in South America have been originally conceived as fault compilations, where some key parameters required for SHA have not been suitably surveyed or exhibit significant discrepancies among themselves. This Topic was mainly dedicated to compile under uniform standards the existing information and to define or estimate key parameters of seismogenic signification for selected structures, more relevant regarding their contribution to hazard.

The South America Risk Assessment (SARA) project promoted a closer link between the earthquake geology community in South America and the hazard modeling one with the aim of incorporating the hazardous faults of South America as one of the databases feeding the SARA seismic hazard source model. This task has been undertaken under a collaborative network by a team of geologists grouped into the “Grupo Sudamericano de Neotectónica”, and led by Carlos Costa undertook the complex and challenging task of assimilating and homogenising active fault data across South America. This data came from many published sources including the International Lithosphere Program II-2 project (Costa et al., 2000; Audemard et al., 2000; Lavenu et al., 2000; Paris et al., 2000; Saadi et al., 2002; Egüez et al., 2003; Macharé et al., 2003), the Multinational Andean Project (Proyecto Multinacional Andino, 2009) and existing national neotectonic databases and fault data collections.

Because data availability and accuracy is very heterogeneous country by country and in many cases this information was obtained and/or created under different criteria, harmonizations efforts on prioritary faults were needed. The following criteria were applied for selecting prioritary structures:

  • Slip rates in excess or equal to 0.1 mm/yr. Applies for rates already available or estimated by compilers through quantitative-semiquantitative data,
  • Evidence of Late Pleistocene tectonic activity (confirmed and suspected), and/or
  • Confirmed or suspected sources of earthquakes with magnitudes greater than Mw5.5.

Argentina: More than 500 structures have been compiled by several contributors under the coordination of the geological survey (SEGEMAR). Although most of them contain no relevant info for SHA purposes (around 175 neotectonic structures conformed the priority list). In the figures below are presented the whole database of neotectonic structures [faults ~ 430, folds ~ 75], and those selected following the priority criteria defined. |  SEGEMAR neotectonic structures |  Argentina priority faults|

Bolivia Brazil
Bolivia fault traces
Near 20 structures were compiled in [xls] format by Observatorio San Calixto experts with parameters similar to those requested by SARAT2 guidelines. Then, this information was pre-processed, checked and incorporated. At this stage, only data provided for NE Brazil was incorporated, considering was the one qualifying for SARA requiring parameters. It is expected to incorporate more data, as soon as relevant parameters could be surveyed or estimated for other structures already mapped but lacking of relevant parametric information.

Chile: More than one hundred structures have been so far compiled by Pontificia Universidad Católica de Chile and Universidad Catolica del Norte, most of them constituting fault sections of Atacama, Liquiñe-Ofqui and Lago Fagnano fault systems. This information has partly been compiled under ArcGis format. Then, the data was pre-processed, checked and incorporated using the platform designed by GEM team for SARA T2.

Colombia: The geological survey (Colombian Geological Survey) manages an Gis-based digital database and map of Quaternary deformation (Mapa geológico de Colombia). A selection from this database was made taking into account the parameters requested by SARA-T2 guidelines and the priority criteria.
SGC Fault Database Priority Faults

Ecuador: There is a digital database and maps actualised and developed under a joint research effort with colleagues from Ecuador (Instituto Geofísico/EPN) under a similar format, in collaboration with L. Audin (NeoTec, IRD, Francia). A selection of structures from this database was made taking into account the parameters requested by SARA-T2 guidelines and the priority criteria.

Perú: As Ecuador,the geological survey Servicio Geológico del Perú-INGEMMET has developed a GIS on Quaternary structures in collaboration with NeoTec, IRD, Francia. A selection of neotectonic structures was incorporated into the SARA T2 platform following the guidelines and the priority criteria.

Venezuela: Fundación Venezolana de Investigaciones Sismológicas-Funvisis has developed the most elaborated datasets of Quaternary faulting, as a result of the long lasting work of FUNVISIS in this area. Fault data are already related to seismogenic sources, although the digital format is not fully compatible with SARA T2 requirements. Then, this information was pre-processed, checked and incorporated following the priority criteria.

Quaternary active structures known up to present in the region, particularly considering their possible seismogenic relevance, have been uploaded under common criteria in a homogeneous informatics platform creating a harmonized database with information provided by national agencies and universities of the following countries: Colombia, Venezuela, Ecuador, Bolivia, Brazil, Argentina, Peru and Chile.
Relevant parameters such as geometry, kinematics, and activity rate for each structure have been compiled under a GIS-supported platform and spatially linked to the structure traces.

Left: Database of crustal “hazardous” faults collected in the framework of SARA, with different colors for the priority faults. In black the faults with insufficient information and/or discarded. Right: North Andean 3D fault representation.

Database of crustal “hazardous” faults North Andean 3D Faults representation
  • Audemard, F.A., Machette, M., Cox, J., Dart, R., Haller, K. (2000). Map and Database of Quaternary faults in Venezuela, U.S. Geological Survey Open-File Report 00-108. US Open-File Report
  • Costa C., Machette M. N., Dart R. L., Bastias H. E. , Paredes J. D. , Perucca L. P., Tello G. E. , and K. M. Haller (2000). Map and database of Quaternary faults and folds in Argentina. US Open-File Report
  • Costa, C., H. Cisneros, M. M. Machette, R. L. Dart, (2003). A new database of Quaternary faults and folds in South America. ILP Task Group II-2 (western Hemisphere). Proceedings of the American Geophysical Union, Fall Meeting 2003, abstract #T31C-0854Proceeding
  • Egüez, A., Alvarado, A., Yepes, H., Machette, M. N., Costa, C., Dart, R. L., and Bradley, L. A. (2003). Database and map of Quaternary faults and folds of Ecuador and its offshore regions. US Geological Survey Open-File Report, 3, 289. US Open-File Report
  • Getsinger, J. S., C. J. Hickson (2000). Multinational Andean Project (MAP): Geological co-operation across borders. Journal of the Geological Association of Canada, 27(3): 121-129.Paper
  • Lavenu, A., Thiele, R., Machette, M.N., Dart R.L., Bradley, L., Haller, K.M. (2000). Map and database of Quaternary faults in Bolivia and Chile. USGS Open-File Report 00-283. US Open-File Report
  • Macharé, J., Fenton, C. H., Machette, M. N., Lavenu, A., Costa, C., and Dart, R. L. (2003). Database and map of Quaternary faults and folds in Peru and its offshore region. USGS Open-File Report 03-451. US Open-File Report
  • Paris, G., Machette, M.N., Dart, R.L. and Haller, K.M. (2000). Map and Database of Quaternary Faults and Folds in Colombia and its Offshore Regions. 00-0284, U.S. Geological Survey, 60p. US Open-File Report
  • Saadi, A., Machette, M. N., Haller, K. M., Dart, R. L., Bradley, L., and Souza, A. M. (2002). Map and database of Quaternary faults and lineaments in Brazil. US Geological Survey. USGS Open-File Report 02-230. US Open-File Report

The SARA Hazardous crustal faults DATA-SET can be downloaded at the link provided below - Please read the license and disclaimer attached.

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  • hazard_rt2.txt
  • Last modified: 2016/08/12 10:48
  • by Julio Garcia