Reassessment of macroseismic intensities for two earthquakes in Colombia: Tumaco (1979, Mw = 8.1) and Armenia (1999, Mw = 6.1), using the ESI-2007 scale
Introduction
Geology and tectonics both imply a seismically active territory in Colombia with important historic earthquakes that have caused damage to the economy, society, and environment (Espinosa, 1999; Lalinde and Sánchez, 2007). Studying the surface environmental effects of earthquakes results in new knowledge that can be used for future assessment, prevention, and mitigation of earthquake hazards.
Widely used traditional seismic intensity scales such as the Modified Mercalli 1931 (herein called “MM”) (Wood and Neumann, 1931); Medvedev–Sponheuer–Karnik – MSK-64 (UNESCO, 1965); and the European Macroseismic Scale 1998 – EMS-98 (Grünthal, 1998) incorporated a variety of effects on various “receivers” or “sensors” to achieve precision in the severity of seismic shaking. Initially, the scales included effects perceived by humans, infrastructure, and a few effects in nature, but during the second half of the 20th century the effects of earthquakes on the environment were largely overlooked, partly due to the intrinsic complexity of the earthquake process itself and the large variability of surface effects that in many cases require specific geology studies (Mosquera-Machado et al., 2009; Sánchez and Maldonado, 2016), whereas the inclusion of effects on humans and buildings progressively increased in studies and quantification because of their ease of analysis. Nowadays, it is known that traditional macroseismic intensities need to be complemented with other effects, which implies reassigning intensity values. A number of studies (Michetti et al., 2004; Heddar et al., 2016; Serva et al., 2016; Chunga et al., 2018) show substantial evidence on the informative potential of coseismic effects to quantify earthquakes and their intensity fields and to complement the intensities calculated with traditional scales. It is also known that the macroseismic severity of earthquakes results from the cumulative effect of the source dynamics (vibrations generated during rupture and finite deformations), terrain acceleration during the propagation of surface waves, and locally the site effects on the amplitude of waves. Thus, seismic intensity is related to a classification of effects that allows measurement of the severity of terrain shaking over an ample range of amplitudes and frequencies, including both static deformations and dynamically induced effects (Michetti et al., 2007).
The Environmental Seismic Intensity Scale ESI-2007 incorporates the surface effects caused by earthquakes on the environment to assess intensities, which in conjunction with data from other scales allows for a more complete vision of the earthquake effects on the terrain and makes it possible to compare the intensities of earthquakes: 1) through time because environmental effects are independent of socioeconomic and urbanistic conditions and types of buildings, and 2) in space because it is possible to assign intensities in locations with few or no inhabitants and compare intensities between rural and developed areas. The ESI-2007 scale offers an alternative perspective in earthquake intensity analysis by taking into account the geological configuration of the terrain. As an example of the usefulness of the ESI-2007 scale, consider an earthquake affecting two areas with different degrees of development (e.g. types of buildings and standards of living); the comparison of assessed intensities among traditional scales would produce different levels of severity of shaking whereas with the ESI-2007 scale the intensity values should be quite similar.
Colombia is a suitable region for implementation of seismic intensity based on the ESI-2007 scale because seismicity is pervasive and there are large inhabited areas where intensities cannot be assessed by other methods (Fig. 1). Also, the intensities during many historical earthquakes can be reappraised to understand the earthquake process and to prepare in case of a repeat. In the following, we present an organized compilation of surface effects mined from published literature and analysis of ESI-2007 intensities for two important historical earthquakes: Tumaco (December 12th, 1979, Mw = 8.1, hypocentral depth = 24 km) and Armenia (January 25th, 1999, Mw = 6.1, hypocentral depth = 15 km), referred to herein as TE and AE, respectively, both of which caused significant damage and losses in ample regions. First, the listing of environmental effects found in various sources of information was used to calculate ESI-2007 intensities; second, new isoseismal maps were generated and compared with those for traditional scales; finally, intensities were reassessed for both earthquakes to make a contribution to future plans of land use in the affected regions.
Section snippets
The January 25th, 1999 (Mw = 6.1) Armenia earthquake
The AE was felt strongly in the city of Armenia and nearby towns and caused major damage that resulted in 1,171 human fatalities, 4,765 injured, 45,019 affected dwellings, 6,408 Eje Cafetero farms with terrain damage, and over $2 billion worth of economic losses (Espinosa, 1999;INGEOMINAS a, 1999;INGEOMINAS b, 1999;INGEOMINAS c, 1999;INGEOMINAS d, 1999; Sarabia and Cifuentes, 2010). The AE has been one of the most devastating earthquakes in Colombia and highlighted the need for better land use
The Armenia earthquake (January 25th, 1999, Mw = 6.1)
The study area for the AE is located in the Eje Cafetero region of central western Colombia within a polygon bounded by the coordinates 3.712°–5.132° N and 76.127°–75.045° W. Before the AE, the region had already experienced a number of moderate earthquakes with M > 5.0 and mostly with depths larger than 50 km (Table 1).
The nearest significant earthquake to the city of Armenia was the Ms = 6.7 event on December 20th, 1967, with an epicenter between the cities of Armenia and Calarcá and I0MM
Data and methods
The data on environmental effects during the AE and TE were compiled from authoritative sources. In the case of the AE, the data was mined from technical reports (INGEOMINAS a, 1999,INGEOMINAS b, 1999,INGEOMINAS c, 1999,INGEOMINAS d, 1999); morphotectonic and seismology studies (Gallego et al., 2005; Monsalve and Vargas, 2007); a macroseismic study (Sarabia and Cifuentes, 2010); an analysis of the societo-economic impacts of disasters (CEPAL, 1999); a B.Sc. thesis on the mass wasting processes (
Traditional isoseismal maps for AE and TE
The classic isoseismal maps for the AE (Fig. 5), based on EMS-98 and MM intensities, show similar patterns: smoothly varying concentric intensity curves with slight elongation in the N–S direction for intensities ≤ 8, and variable degree and direction of elongation for intensities ≥ 9. The map digitized from the USGS, based on MM intensities, has somewhat irregular curves, except for intensity 9, which is smooth and has a clear elongation in the N–S direction. The areas within each intensity
Discussion
Analysis of the AE and TE begins by considering the data upon which the research was conducted, namely, the environmental effects caused during both earthquakes and compiled in this work from published sources. In the case of the AE, a relatively fair group of sites with measurable secondary effects was compiled though their locations near roads, suggesting that access to the area was a determining factor in the documentation and description of the reporting campaigns. This of course implies
Conclusions
The environmental and geological effects following the TE (December 12, 1979, Mw = 8.1) and AE (January 25, 1999, Mw = 6.1) were compiled and analyzed and the ESI-2007 intensities were determined using secondary effects. Measured site-level and locality-level maximum intensities in each case were usually higher than those for classic scales which saturate at the strongest intensities and thus the damage represented by environmental effects becomes the only means to assess that strength of
CRediT authorship contribution statement
Freddy Tovar: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Writing - review & editing, Visualization. John J. Sánchez: Conceptualization, Methodology, Investigation, Writing - review & editing.
References (64)
- et al.
Macroseismic intensity assessment of 1885 Baramulla earthquake of northwestern Kashmir himalaya, using the environmental seismic intensity scale (ESI 2007)
Quat. Int.
(2014) - et al.
Distribution of discrete seismic asperities and aseismic slip along the Ecuadorian megathrust
Earth Planet Sci. Lett.
(2014) - et al.
Centroid-moment tensor solutions for january–march 1999
Phys. Earth Planet. In.
(2000) - et al.
Use of long-period surface waves for rapid determination of earthquake source parameters
Phys. Earth Planet. In.
(1981) - et al.
Leyes de atenuación para sismos corticales y de subducción para el Ecuador
Revista Ciencia
(2010) - et al.
Aproximación a un modelo de susceptibilidad a movimientos de masa en el eje cafetero, Colombia
(2002) - et al.
Reseña explicativa del Mapa geológico del Departamento de Nariño, Informe No 1818
(1980) - et al.
The rupture process of the great 1979 Colombia earthquake: evidence for the asperity model
J. Geophys. Res.
(1984) El terremoto de enero de 1999 en Colombia: Impacto socioeconómico del desastre en la zona del Eje Cafetero
(1999)- (1985)
Vulnerability and site effects in earthquake disasters in Armenia (Colombia)
I—Site Effects. Geosciences
Earthquake ground effects and intensity of the 16 April 2016 M w 7.8 Pedernales, Ecuador, Earthquake: implications for the source characterization of large subduction earthquakes
Bull. Seismol. Soc. Am.
Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence from multichannel seismic reflection data acquired across the northern Ecuador–southwest Colombia margin
J. Geophys. Res.
Geomorfología general y sedimentología de la Bahía de Tumaco. Memorias, VI Seminario Nacional de Ciencias y Tecnologías del Mar, Comisión Colombiana de Oceanografía, Bogotá
Indicios neotectónicos de la Falla de Ibagué-Piedras, Departamento del Tolima, Colombia
Rev. CIAF
Correlación y geocronología Ar-Ar del basamento Cretácico y el relleno sedimentario Eoceno superior - mioceno (Aquitaniano inferior) de la cuenca de antearco de Tumaco, SW de Colombia
Rev. Mex. Ciencias Geol.
Algunas enseñanzas del terremoto del Quindío
Sociedad Geografica de Colombia, Academia de Ciencias Geográficas
Estudio de la actividad de la falla de Armenia: Convenio CRQ-Uniquindío, Informe final
Sismo del quindío del 25 de enero de 1999, evaluación morfotectónica y sismológica
Bol. Geol.
Análisis comparativo del fenómeno de licuación en arenas. Aplicación Tumaco (Colombia)
Análisis sísmico del puente carrizal y contribuciones a la peligrosidad sísmica del Ecuador
Geological Map of Colombia 2015. Scale 1:100 000. Servicio Geológico Colombiano, 2 Sheets. Bogotá
Plancha 5–08 del Atlas Geológico de Colombia 2015. Escala 1:500 000
Armenia: Una Mirada Ambiental. La Dimensión Físico-Espacial diez años después del sismo. Caso de Estudio Plan Piloto-Brasilia Nueva
Mapa Geológico Generalizado del Departamento del Quindío, escala 1: 100.000
Evaluación de amenaza por tsunami. Trabajo de Grado
Use of the ESI-2007 scale to evaluate the 2003 Boumerdès earthquake (North Algeria)
Ann. Geophys.
The great Tumaco, Colombia earthquake of 12 december 1979
Science
Terremoto del Quindío (Enero 25 de 1999)
Informe técnico preliminar
Terremoto del Quindío (Enero 25 de 1999)
Informe técnico preliminar No. 2, Armenia-Quindío
Terremoto del Quindío (Enero 25 de 1999). Informe técnico preliminar No. 3, evaluación de daños en Calarca
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